Dissertations / Theses on the topic 'Fluoride Sensors'

In many engineering applications, it is desirable to know the behaviour of structures and systems under loading conditions. One reason is to help optimize the design and prevent damage and failure which might occur during in service and operation. Damage represents a serious problem which can cause catastrophic failure of structures, machines and systems. Therefore for safe operation, efficient and reliable methods for inspection and monitoring of damage are required. Different methods for health monitoring of structures such as non destructive testing (NDT) and strain gauges are widely used. These methods have proven to be efficient in terms of resolution and response. However, some disadvantages associated with them include the vicinity of the area under inspection which must be well known, equipment to acquire the necessary information is expensive and in many cases high skills are required for operation. On the other hand, advances in materials science and MEMS systems has promoted the use of new materials with piezoelectric properties. This include mainly polymeric and ceramic materials which after processed can be used for structural health monitoring. These materials offer a number of advantages such as lightweight, sensitivity, toughness, durability, and low cost. The present research work investigates the feasibility of using a polymeric material, Polyvinylidene Fluoride (PVDF) as a sensor for deformation and defect detection in structures. The sensors are embedded in composite cantilevered type beams to detect defects at distinct locations along the beam’s length. The defect detection method proposed is based on experimental tests and Finite Element simulations. Experimental tests on defect free and beams with manufactured internal flaws were conducted. Numerical (FEM) simulations of defect free and flawed beam models containing sections of reduced elastic modulus to represent the damage were conducted using ANSYS software. The experimental tests have been used for the validation of the numerical solution. Results have shown that the defect location changes the stiffness and indeed the frequency of vibration. For flaws near the fixed end of the beams, lower frequencies are obtained as compared to flaws away from the fixed end. PVDF sensors were used to acquire the natural frequencies of the beams for the first mode of vibration. Good agreement was verified between experimental and numerical simulation results. The work has demonstrated that PVDF film sensors can be used as possible candidates for defect detection. The analysis of the behaviour embedded PVDF sensors near the fixed end of cantilever beams, represents an initial and important step towards the application of measuring static and dynamic behaviour of structures as part of a health monitoring process.

Although bond-normal stresses have been shown to be responsible for the failure of most laboratory adhesive joint geometries, the measurement of these stresses has been accomplished only through the use of very sophisticated optical techniques. In order to develop a more versatile measurement technique, poly(vinylidene fluoride) film was used to develop piezoelectric stress sensors. The sensitivities of the film to normal stresses in the three principal material directions of the orthotropic film were accurately measured using a charge amplifier and a storage oscilloscope. These measured sensitivities comprised the calibration constants of the film. In order to reduce the detrimental effect on bond strength caused by embedding the low surface energy film into adhesive bondlines, surface treatment methods were investigated using contact angle studies, XPS analysis and 1800 peel and tapered double cantilever beam adhesion specimens. An acid etch using a mixture of acetic, phosphoric and nitric acids was found to greatly improve the bond strengths to an epoxy adhesive without reducing the piezoelectric activity of the film. The bond-normal stresses in both the elastomeric butt joint and the single lap shear joint were measured using the developed stress sensors. Comparison of the measured stresses with calculated values obtained from closed-form analytical solutions and finite element analysis for the stresses was excellent. The piezoelectric sensors do have several important limitations. The piezoelectric activity of the film is lost at temperatures above 100°C (210°F). Also, the sensors are only sensitive to dynamic loads. Nonetheless, the sensors provide an accurate means of measuring peel stresses in many adhesive joints of practical interest.
Ph. D.

The main purpose of this thesis was to investigate and characterize the use of piezoelectric yarn for use in textile (fingertip) pressure sensors in glove applications. Such applications could include healthcare, security and safety, game applications or intelligent control. Piezoelectric materials generate a voltage when pressed or squeezed. Poly(vinylidene fluoride) (PVDF) is a polymorphic material with piezoelectric properties. PVDF yarns were integrated into block sensors. These blocks consist of thermoplastic material glued to a knitted supporting fabric. The electrical signal given off by the PVDF yarn was measured with the help of an oscilloscope. The block sensor generated a distinguishable signal under a dynamic compression of 0.003 N, indicating that the structure is sensitive enough compared to the average male fingertip sensitivity threshold (0.0054N).
Program: Master programme in Textile Engineering

The synthesis and development of new materials and the improvement of the existing materials are a continuous quest for scientists. There is a constant need for new materials that have more advantages over the existing ones. The research to develop new materials can be appreciated in high magnitude, as the new materials improve the livelihood. In this dissertation, we are presenting our progress in developing new materials, such as fluorescence fluorophores as probes, and esterification catalysts. In the first part of the dissertation, the synthesis and characterization of a novel silicon analog of fluorescein (silyl fluorescein) was studied in detail. The photo-physical properties and toxicity studies of these fluorophores are also discussed. Compared to fluorescein, silyl fluorescein displayed a 90 nm longer wavelength in its absorption and emission. Silyl fluorescein showed good solubility in water and organic solvents, and has a considerable fluorescence quantum yield compared to fluorescein. Silyl fluorescein was found to be moderately toxic under light and non-toxic in dark, where as fluorescein toxicity was found to be greater than silyl fluorescein both in the dark and under light. Two probes from our novel silyl fluorescein fluorophore were developed and studied. SIF HySOx is probe for hypochlorous acid (HOCl), which is a reactive oxygen species (ROS) found in cells that are stressed due to various diseases. The HOCl probe was synthesized and its photo-physical properties were studied. It was found to be selective and sensitive only to HOCl. A fluoride probe (DTBDMS SIF P) was also developed from silyl fluorescein. Its synthesis and photo-physical properties were also studied. The probe displayed excellent selectivity and sensitivity to fluoride (TBAF) in the presence of other halides and bases. Future directions on novel fluorophore are briefly mentioned. Second part of the dissertation is focused on the screening of two organic esterification catalysts which were synthesized by Dr. Liu and Dr. Wong. The catalysts which are synthesized from pyridine and dinitrobenzene moieties were screened with several carboxylic acids and alcohols. Catalyst 8-4 was shown to be moderately active in the esterification of carboxylic acids and alcohols. It has no selectivity in the esterification of primary, secondary, tertiary alcohols, and the carboxylic acids that are attached to those carbons. Catalyst 9-1 however, was more efficient in the esterification of carboxylic acids and alcohols. Catalyst 9-1 displayed selectivity in the esterification of primary, over secondary, over tertiary alcohols, and the carboxylic acids that are attached to those carbons. Catalyst 9-1 gave up to 95% isolated yields.

En detection d'obstacles, dans le cadre de l'application automobile, la voie infrarouge passive fondee sur l'imagerie thermique (bande 8-14m), est apparue, a long terme, la solution ideale. Les objectifs de faible cout de fabrication ont conduit a la realisation d'une matrice de 32x32 detecteurs pyroelectriques utilisant le polyvinylidene trifluoroethylene (pvdf-trfe), depose sur un circuit de lecture de type cmos selon les techniques habituelles du depot des resines de la microelectronique. Ce memoire presente un travail de fond sur la comprehension de la detection pyroelectrique par le pvdf-trfe, a temperature ambiante. Les progres des performances des senseurs proviennent essentiellement de l'etude du comportement pyroelectrique du materiau dans la structure technologique, des modelisations thermo-electriques (1d et 3d) et des caracterisations electro-optiques des senseurs integres. Les parametres cruciaux du modele de detection ont ete determines et les differentes sources de bruit des dispositifs analysees. La reponse mesuree est quasiment optimale et valide notre modele. Actuellement, la sensibilite du capteur est essentiellement limitee par le bruit de l'electronique plan focal: la mise en uvre du senseur est determinante. Le resume des performances que constitue nedt=0. 4k a f/l, est encore actuellement majore par un exces de bruit de lecture. L'optimisation de son fonctionnement laisse raisonnablement esperer une valeur de l'ordre de 0. 2k. Pour la detection sur route, nous proposons une structure adaptee a la geometrie de prise de vue sur route par une optique faible cout. Nous validons par des simulations, une architecture analogique dans le plan focal, permettant de reduire le debit d'informations issu du capteur

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

During this project it was investigated how the newly developed piezoelectric PVDF bicomponent fibre behaved when integrated in different weave constructions. The possibility to integrate conductive yarns as outer electrode was studied in order to see if it was possible to create a fully textile piezoelectric sensors. The piezoelectric properties of the bicomponent fibre is given by the sheath material, which is a polymeric material known as poly(vinylidene fluoride) (PVDF). Today only piezoelectric film made by PVDF is commercially available, but with a flexible PVDF bicomponent fibre it improves the possibility to integrate piezoelectric material into a textile construction. In this study the PVDF bicomponent fibre was integrated in the warp direction into weave constructions, such as plain weave, twill and weft rib. All the woven bands included 60 PVDF bicomponent yarns, with 24 filaments in each bundle and the average width of the bands produced was 30 mm. Different conductive materials and fibres, acting as outer electrode, were coated or integrated together with the PVDF fibre and the behaviour of the PVDF fibres was analysed. All the woven samples went through corona poling with a voltage of 7 kV in 70 ⁰C for 3 min. The weave construction that gave highest piezoelectric output signal was twill with weft that has low tex. The twill construction gave a range amplitude of 1.5- 3.3 V when subjected to a dynamic strain of about 0.25% at 4 Hz. It was shown that different conductive materials influenced the PVDF fibre in different ways, due to the resistance of the material. It was also shown that it was possible to integrate piezoelectric bicomponent fibre into a textile construction and that a fully textile piezoelectric sensor could be produced by using conductive yarns as outer electrode.
Program: Masterutbildning i textilteknik,

In this experimental study the in-lined poled piezoelectric poly(vinylidene fluoride)(PVDF) bicomponent fiber was investigated the suitability in applications within the area of textile sensors when used in a bowel stent. Today there are only piezoelectric films made of PVDF available. Compared to a film, a fiber increases the amounts of application abilities. In this study a plain weave, resembling a coordinate system was made of the piezoelectric PVDF fiber and tested on top of two different beds; one hard and one elastic made of foam. The structure was then developed into two structures; one integrated in the stents structure with a plain weave pattern and one secondary structure as a plain weave placed onto the stent. Two test methods were developed in order to resemble the bowel movements to test the two piezoelectric PVDF fiber based structures. A reliability test in a reometer was made of the fiber, giving high differences in mean values. An in vivo test was conducted in a pig where the stent was placed in the orifice of the stomach. Both structures shown response when both developed methods was used. Due to large irregularities within the piezoelectric PVDF fiber the evaluation between the two structures was not possible. The most favorable structure was the secondary structure due to the larger continuous process ability and application areas. It was also seen that the reliability of the piezoelectric PVDF fiber is low, giving a non-reliable sensor.
Program: Textilteknik

Arbetet syftar till att skapa en prototyp av en textil trycksensor som kan känna av och skilja på olika typer av belastning. En lämplig metod för att på ett vetenskapligt sätt testa sagda prototyp har också utvecklats. Prototypen har tillverkats för hand på en datoriserad vävstol och de ingående materialen är piezoelektrisk poly(vinyldifluorid), PVDF, tvinnad tillsammans med ett konduktivt garn, Shieldex®, samt polyester. När PVDF-fiber utsätts för töjning genererar de en spänning, vars storlek står i relation till töjningen. Den vävda konstruktion som valdes till prototypen är en distansvara där väftinläggen lagts in i 7 olika lager för att skapa volym. Därmed möjliggörs en töjning av PVDF-fibern som relaterar till trycket strukturen utsätts för. För att utvärdera strukturen skapades tre likadana trycksensorer innehållandes fyra PVDF-fiber som lagts in med ett mellanrum på ca 1,5 cm. Dessa prototyper har sedan fästs på en egentillverkad ramp och PVDF- samt Shieldex®-garnet har kopplats in till ett oscilloskop. Därefter har vikter rullats över prototypen för att generera spänning, vilken har kunnat uppmätas med oscilloskopet. De uppmätta resultaten har analyserats och utvärderats med hjälp av Excel. Testerna visade tydligt att spänningen som uppmättes stod i relation till vikternas storlek; högre vikter gav en mätbart större spänning. Det finns dock stor varians bland resultaten och utvärdering av samtliga prover visar på stora standardavvikelser hos samtliga fiber. Detta innebär att även om det är tydligt att ökad vikt medför ökad signal så kan det finnas svårigheter i att avgöra storleken på vikten utifrån den uppmätta spänningen.
The aim of this project was to create a sensor in textile material which can register and recognize different kinds of pressure. A suitable method has been developed in order to scientifically investigate and evaluate the sensitivity of the prototypes. The prototypes have been produced with a computerized hand weave machine and the materials used were polyester and piezoelectric PVDF-fiber, twisted with a conductive yarn, Shieldex®. When a force is applied to the PVDF-fiber, causing an extension of the fiber, a voltage is generated directly related to the applied force. The final prototype is a woven textile with integrated monofilaments and weft inserted in seven different layers to create a voluminous structure. An extension by the PVDF-fiber is there by enabled to occur which is related to the force applied onto the structure. Three equable prototypes were produced, each consisting four separated PVDF-fibers which were inserted with a distance of 1, 5 cm from each other. The prototypes were further attached one by one on a homemade ramp and the PVDF- and Shieldex®-fibers were connected to an oscilloscope. Different weights were then rolled from the top of the ramp, generating a voltage each time it pressures a fiber, which were seen on the computer software of the oscilloscope. The results were afterwards analyzed and evaluated using Excel. A clear relationship between applied force and generated voltage is shown although there is a great variety among the test results on each weight along with large standard deviations. The exact weight generating a specific voltage is therefore difficult to determine.

The synthesis, characterisation and anion binding properties of a series of mono- and bifunctional Lewis acidic borylferrocene compounds are described within this thesis. The original parent compound FcBMes₂ (3.1), revealed a versatile route for the synthesis of such borylferrocenes and subsequently the analogous compound Fc*BMes₂ (3.2) was synthesised. The anion binding properties of (3.1) and (3.2) were investigated and both were shown to bind one equivalent of cyanide. The binding event was signalled by an electrochemical shift (ca. -560 mV) and a quenching of bands at 510 or 542 nm respectively in the UV/Vis spectrum, while the mode of anion binding in the solid state was established by X-ray crystallography for [ⁿBu₄N]⁺[(3.1)·CN]⁻. Incorporation of a suitable redox active dye (i.e. tetrazolium violet for 3.2) allowed conversion of the electrochemical response to a colorimetric change on cyanide binding. However, a competing response for fluoride is also seen for (3.1) and (3.2). Thus a two component system is reported involving (3.2) and the boronic ester FcB(OR)₂ (3.4), [where (OR)₂ = OCH(Ph)CH(Ph)O], which from previous research is known to selectively bind fluoride, and allows for selective colorimetric cyanide sensing by simple Boolean AND/NOT logic. 1,4-C₆H₄(BMes₂)[B(OR)₂] (3.5), 4,4-C₁₂H₈(BMes₂)[B(OR)₂] (3.6) and 1,1′-fc(BMes2)(B(OR)2) (3.7) were synthesised as possible single molecules for discrimination between cyanide and fluoride. (3.5) and (3.6) proved only capable of binding one equivalent of either anion, (3.7) showed some ability to bind two equivalents of fluoride however based on ESI-MS studies although only in the presence of a large excess of anion. Systematic variation of the para-boryl substituent was investigated by synthesis of compounds FcB(Xyl^F)₂ (4.1), FcB(Xyl)₂ (4.2) and FcB(Xyl^OMe)₂ (4.3). Anion binding studies reveal a linear increase in fluoride binding affinity consistent with that expected based on the para,/em>-Hammett parameters, however with only minor differences, while no pattern is observed with respect to their cyanide binding capabilities. The addition of neutral and cationic peripheral substituents has been investigated through synthesis of [1,2-fc(CH₂NMe₂)BMes₂] (4.6) and [1,2-fc(CH₂NMe₃)BMes₂]⁺ (4.7). Subsequent binding studies revealed (4.6) to be moisture sensitive, however reaction of (4.7) with fluoride and cyanide led to formation of the adducts [(4.7)·F]⁻ and [(4.7)·CN]⁻. The anion affinity of (4.7) exhibits a substantial increase when compared to the parent compound (3.1). Even when compared to the isomeric 1,1′ system an increase of approximately three orders of magnitude is seen attributed to the closer nature of the cationic charge and in the fluoride adduct the presence of a cooperative intramolecular hydrogen bond. The 1,1′-bifunctional analogues of the mono-substituted systems were synthesised [e.g. 1,2-fc(BMes₂)₂ (5.1)] and shown to complex two equivalents of fluoride or cyanide in acetonitrile. The 1:1 cyanide adduct of (5.1) was isolated in chloroform however, no evidence for chelation was observed. The analogous systems 1,2-fc(BMes₂)₂ (5.5), 1,2-fc(BXyl₂)2 (5.7), and 1,2-fc(BMes₂)(BXyl₂) (5.8) were also investigated. Reaction of (5.5) with fluoride and cyanide revealed it to bind only one equivalent of either anion, neither however was bound in a chelating fashion although X-ray crystallography revealed cyanide binds exo whilst fluoride binds endo to the B···B cavity. Finally the kinetics of fluoride binding were studied by UV/Vis spectroscopy and showed a systematic increase in rate constant upon reduction of steric bulk.

[EN] Abstract The present PhD thesis entitled "Supramolecular Chemistry: New chemodosimeters and hybrid materials for the chromo-fluorogenic detection of anions and neutral molecules" is based on the application of supramolecular chemistry and material science principles for the development of optical chemosensors for anions and neutral molecules detection. The second chapter of this PhD thesis is devoted to the preparation of chemodosimeters for the chromo-fluorogenic detection of fluoride, diisopropyl fluorophosphates (DFP) and hydrogen sulfide. The optical detection of fluoride anion was achieved by using a pyridine derivative containing a t-butyldimethylsilyl ether group. Aqueous solutions of the chemodosimeter were colorless but turned yellow upon addition of fluoride anion. Also a remarkable enhancement in emission was observed only upon the addition of fluoride. The optical changes were ascribed to a fluoride-induced hydrolysis of the silyl ether moiety. Also a chemodosimeter for the optical recognition of DFP, a nerve agent simulant, was prepared. In this case, the chemodosimeter was based on a stilbene pyridinium derivative functionalized with hydroxyl and silyl ether moieties. Aqueous solutions of the chemodosimeter were colorless changing to yellow upon DFP addition. The optical changes were ascribed to a hydroxyl phosphorylation followed by a fluoride-induced hydrolysis of the silyl ether group. Besides, that probe was implemented in test strips and DFP detection in gas phase was accomplished. Finally, the fluorogenic recognition of hydrogen sulfide anion was explored. For this purpose different fluorophores were selected and fucntionalized with 2,4-dinitrophenyl ether groups. The prepared probes were neraly non-emissive but remarkable emission enhancements upon addition of hydrogen sulfide were observed. The emission enhancements observed were due to a selective sulfide-induced hydrolysis of the 2,4-dinitrophenyl ether moiety that yielded the free fluorophores. Another set of chemodosimeters equipped with azide and sulfonylazide moieties were prepared. Again these probes were non-fluorescent but upon addition of hydrogen sulfide an important enhancement in emission was found. The selective response was ascribed to a reduction of the azide and sulfonylazide moieties to amine and sulfonylamide induced by hydrogen sulfide anion. Besides, the viability assays showed that these dosimeters were essentially non-toxic and real-time fluorescence imaging measurements confirmed their ability to detect intracellular hydrogen sulfide at micromolar concentrations. The third chapter of this PhD thesis was devoted to the preparation of nanoscopic gated materials and their use in sensing protocols. In a first step a gated material for the optical detection of glutathione (GSH) was prepared. For this purpose MCM-41 mesoporous silca nanoparticles were selected as inorganic scaffold. The pores were loaded with safranine O and the external surface was functionalized with disulfide-containing oligo(ethylene glycol) moieties. Dye delivery from aqueous suspensions of the sensory material was only observed in the presence of GSH. The signalling paradigm was ascribed to the selective reduction of the disulfide bond by GSH which induced pore opening and dye release. Also capped organic-inorganic hybrid materials for the selective detection of hydrogen sulfide were prepared and characterized. In this case the same MCM-41 support was used and charged with [Ru(bipy)3]2+ dye. Then, the external surface was functionalized with Cu(II)-macorcyclic complexes and finally, the pores were capped by the addition of the bulky anion hexametaphosphate. Aqueous suspensions of this material showed negligible dye release whereas in the presence of hydrogen sulfide anion a remarkable colour change was observed. This optical response was ascribed to a demetallation process of the Cu(II) complex induced by hydrogen sulfide.
[ES] Resumen La presente tesis doctoral titulada "Química supramolecular: Nuevos dosímetros químicos y materiales híbridos para la detección cromo-fluorogénica de aniones y moléculas neutras." está basada en la aplicación de principios básicos de la química supramolecular y de la ciencia de materiales en el desarrollo de sensores ópticos para aniones y moléculas neutras. El segundo capítulo de esta tesis doctoral está dedicado a la preparación de dosímetros químicos para la detección cromo-fluorogénica de fluoruro, diisopropil fluorofosfato (DFP) y sulfuro de hidrógeno. Para la detección óptica del anión fluoruro se sintetizó un derivado de piridina funcionalizado con un t-butildimetilsilil éter. En este capítulo también se describe la preparación de un dosímetro químico para la detección de DFP, que es un simulante de agentes nerviosos. Este dosímetro está basado en un estilbeno funcionalizado con una sal de piridinio que contiene grupos hidroxilo y silil éter en su estructura. Finalmente se prepararon dos familias de sensores para la detección óptica de hidrógeno sulfuro. La primera familia de sensores consiste en fluoróforos comunes funcionalizados con 2,4-dinitrofenil éteres. Los sensores preparados no presentaron una emisión de fluorescencia importante mientras que, en presencia del anión hidrógeno sulfuro, se observó un aumento significativo. La segunda familia de dosímetros también estaba compuesta por ciertos fluorofóros pero, en este caso, funcionalizados con grupos azida y sulfonilazida. Los dosimétros preparados, siguiendo esta segunda aproximación, tampoco dieron una fluorescencia significativa observándose un aumento de la misma al añadir el anión hidrógeno sulfuro. El tercer capítulo de esta tesis doctoral está dedicado a la preparación de materiales híbridos nanoscópicos funcionalizados con puertas moleculares y su aplicación en protocolos de reconocimiento. En primer lugar se preparó un material para la detección óptica de glutatión (GSH). Para ello se emplearon nanopartículas de MCM-41 mesoporosas como soporte inorgánico. Los poros del soporte fueron cargados con el colorante safranina O y la superficie externa funcionalizada con oligo(etilenglicol) conteniendo enlaces disulfuro. También se prepararon y caracterizaron varios materiales híbridos para la detección selectiva del anión hidrógeno sulfuro. En este caso también se empleó, como soporte inorgánico, sílice mesoporosa MCM-41. Los poros del soporte inorgánico fueron cargados con [Ru(bipy)3]2+ y la superficie externa funcionalizada con varios complejos macrocíclicos de Cu(II). El material sensor final fue obtenido al añadir el anion hexametafosfato, que compleja con los complejos de Cu(II), produciendo un bloqueo de los poros.
[CAT] Resum La present tesi doctoral titulada "Química supramolecular: Nous dosímetres químics i materials híbrids per a la detecció cromo-fluorogènica d'anions i molècules neutres." està basada en l'aplicació dels principis bàsics de la química supramolecular i de la ciència dels materials en el desenvolupament de sensors òptics per a anions i molècules neutres. El segon capítol d'aquesta tesi doctoral està dedicat a la preparació de dosímetres químics per a la detecció cromo-fluorogènica de fluorur, diisopropil fluorofosfat (DFP) i sulfur d'hidrogen. Per a la detecció òptica de l'anió fluorur es va sintetitzar un derivat de piridina funcionalitzat amb un t-dibutildimetilsilil èter. En aquest capítol també es descriu la preparació d'un dosímetre químic per a la detecció de DFP, que és un simulant d'agents nerviosos. Aquest dosímetre està basat en un estilbè funcionalitzat amb una sal de piridina que conté grups hidroxil i silis èter en la seua estructura. Finalment varen ser preparades dues famílies de sensors per a la detecció òptica de sulfur d'hidrogen. La primera família consisteix en fluoròfors comuns funcionalitzats amb 2,4-dinitrofenil èters. Els sensors preparats no presentaren una emissió de fluorescència significativa mentre que, en presencia de l'anió hidrogen sulfur, es va observar un augment significatiu. La segona família de dosímetres també estava composada per certs fluròfors però, en aquest cas, funcionalitzats amb grups azida i sulfonilazida. Els dosímetres preparats, seguint aquesta segona aproximació, tampoc donaren una fluorescència significativa observant-se un augment de la mateixa al afegir l'anió hidrogen sulfur. El tercer capítol d'aquesta tesi doctoral està dedicat a la preparació de materials híbrids nanoscòpics funcionalitzats amb portes moleculars i la seua aplicació en protocols de reconeixement. En primer lloc es va preparar un material per a la detecció òptica de glutatió (GSH). Per a aquest propòsit es varen emprar nanopartícules MCM-41 mesoporoses com a suport inorgànic. Els porus del suport varen ser carregats amb el colorant safranina O i la superfície externa funcionalitzada amb oligo(etilenglicol) que contenia enllaços disulfurs. També varen ser preparats i caracteritzats diversos materials híbrids per a la detecció selectiva de l'anió hidrogen sulfur. En aquest cas també es va emprar, com a suport inorgànic, sílice mesoporosa MCM-41. Els porus del suport inorgànic varen ser carregats amb [Ru(bipy)3]2+ i la superfície externa funcionalitzada amb diversos complexos macrocíclics de Cu(II). El material sensor final es va obtindre al afegir l'anió hexametafosfat, que es complexa amb macrocicles de Cu(II), produint un bloqueig dels porus.
El Sayed Shehata Nasr, S. (2015). Supramolecular Chemistry: New chemodosimeters and hybrid materials for the chromo-fluorogenic detection of anions and neutral molecules [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/52598
TESIS

La pollution atmosphérique est omniprésente du fait de nombreuses sources émettrices de composés chimiques. Dans ce contexte, les Hydrocarbures Aromatiques Polycycliques (HAP) sont largement diffusés dans l’air et ont déjà montré des effets délétères sur la santé.Ce travail a consisté en l’évaluation de la neurotoxicité du fluorène, composé choisi comme molécule représentative de la pollution liée aux HAP, chez le rat adulte exposé par voie i.p., par voie orale ou par inhalation. Le modèle d’exposition par inhalation a ensuite été appliqué à l’étude des effets du polluant sur le développement sensori-moteur et l’activité comportementale de l’animal exposé in utero ou au cours de la lactation.Ces études ont montré que le fluorène était susceptible d’affecter le niveau d’anxiété et l’activité locomotrice du rat adulte exposé directement et indirectement au polluant, et n’avait aucun effet sur les capacités d’apprentissage. En revanche, aucune atteinte majeure de la maturation des fonctions sensori-motrices n’a été mise en évidence. L’analyse de la présence du composé et de trois de ses métabolites a par ailleurs montré que le polluant était capable de traverser la barrière hémato-encéphalique et d’être métabolisé au niveau du cerveau. Les réponses physiologiques et comportementales étant variables entre les études, les effets induits par le fluorène dépendent donc de la voie d’entrée, du niveau de contamination et du moment d’exposition.Ces résultats ont ainsi révélé chez l’animal la toxicité comportementale du fluorène à des niveaux de contamination réalistes, confirmant ainsi le risque sanitaire de l’exposition aux HAP tout au long de la vie des individus
Actually air pollution is ubiquitous due to the emission of chemical compound from many sources. In this context, Polycyclic Aromaric Hydrocarbons (PAH)related compounds are widely distributed in the air and have shown deleterious health effects.Fluorene was chosen as a representative compound of PAHs pollution. This work consisted in the evaluation of its neurotoxic effects in adult animals, exposed i.p., orally or by exposure nose-only. The inhalation model of exposure was then applied to the study of its effects on sensorimotor development and on behavioral activity of animals exposed in utero or during lactation.The results showed that fluorene is able to induce behavioral changes in adult animals exposed directly or indirectly on the level of anxiety and the locomotor activity, whereas no effect on learning and memory abilities has been observed. However, no defect on the development of motor and sensory functions was demonstrated. Furthermore, the analysis of the presence of the compound and three of its metabolites showed that the pollutant was able to cross the blood brain barrier and can be metabolized in the brain. Moreover, variations have been observed concerning behavioral and physiological responses between studies, showing that effects induced by fluorene are dependent on the way of administration, the level of contamination and the time of exposure.In conclusion, these results demonstrate in animals the behavioral toxicity of fluorene at levels of contamination corresponding to human cases of exposure, confirming so the risk of PAH exposure throughout life

L'utilisation de materiaux piezoelectriques pour la mesure de contraintes mecaniques dynamiques ou quasi-statiques est une application de longue date ; cependant, l'effet piezoelectrique direct n'est intrinsequement pas adapte aux mesures de contraintes statiques. Dans ce memoire nous presentons un systeme de mesure de contraintes statiques par variation de la frequence de resonance d'un resonateur composite. Nous avons utilise un resonateur composite forme d'un element piezoelectrique (pvf#2) pris entre deux electrodes en laiton, ces electrodes etant elles-memes recouverte de deux feuilles d'elastomere. L'etude et l'analyse du comportement sous contrainte du resonateur montrent que les variations de frequence et d'amortissement de la resonance du systeme sont dues a une variation des impedances de charge de l'element piezoelectrique. Cette variation d'impedance est due essentiellement a variations des caracteristiques de l'interface pvf#2-laiton. Afin de realiser des capteurs de force statique avec le resonateur composite ou la frequence de resonance varie avec la force appliquee, nous avons developpe autour d'un micro-ordinateur une instrumentation appropriee d'etude du resonateur composite. Cette instrumentation est basee sur la mesure de la phase de l'impedance electrique du resonateur, qui presente un maximum a la resonance. Elle nous a permis de caracteriser les differentes configurations du resonateur selon les etats de surface de l'interface pvf#2-laiton. La realisation finale d'un capteur autonome passe par l'integration de celle-ci autour d'un micro-controleur

The growth of sensors and sensing technologies have made significant impact in our day-to-day life. The five principle sensory organs of our body should perform effectively, so that we can lead a good healthy life. Apart from these natural sensors, there are man-made sensors that helps us to cope with diseases, organ failure etc. and enable us to lead a normal life. In recent years, with the prevalence of new kind of diseases, the need for new type of biomedical sensors is becoming very important. As a result, sensors used for biomedical applications have become an emerging technology and rapidly growing field of research. The aim of the present thesis work is to use the piezoelectric property of Polyvinylidene Fluoride (PVDF) film for the development of biomedical sensor and studying its application for human respiration/breathing related abnormalities. PVDF nasal sensor was designed in cantilever configuration and detailed theoretical analysis of the same was performed. Based on theoretical and experimental results, the PVDF nasal sensor dimensions were optimized. Suitable signal conditioning circuitry was designed and a measurement system for biomedical application was developed. The developed PVDF nasal sensor was calibrated using MEMS low-pressure sensor. The PVDF nasal sensor system has been applied in different biomedical applications namely, (i) to monitor human respiration pattern, (ii) to identify different Respiration Rates (RR), (iii) to evaluate Deviated Nasal Septum (DNS) in comparison with other objective method and, (vi) to clinically investigate nasal obstruction in comparison with subjective method. The thesis is divided into seven chapters. Chapter 1 This chapter gives a general introduction about biomedical sensors, piezoelectric sensing principle and PVDF polymer films along with the relevant literature survey. The brief introduction as well as literature survey of techniques used to monitor human respiration and to measure nasal obstruction is also included in this chapter. Chapter 2 This chapter gives details about the design of the PVDF nasal sensor in the cantilever configuration for sensing nasal airflow along with the relevant theoretical equations. Also, the details on the optimization of the PVDF nasal sensor dimensions based on the theoretical and experimental analysis are presented. Chapter 3 This chapter reports the designing of the necessary signal conditioning hardware along with the data acquisition unit for the PVDF nasal sensor. The signal conditioning hardware unit made consists of charge amplifier, low-pass filter and an amplifier. Besides, a complete measurement system for biomedical application was developed using PVDF nasal sensor and its merits and demerits were discussed. Chapter 4 In this chapter, an experimental set-up for measuring human respiration/breathing pressure using water U-tube manometer has been described. Also, the calibration procedure followed for the developed PVDF nasal sensor using a Micro Electro Mechanical Systems(MEMS) low pressure sensor is reported. Apart from these, the details on the measurement of deflection of the PVDF cantilever sensing element using laser displacement setup are provided. In addition, the PVDF nasal sensor was also calibrated for various air flow rates. At the end, a study has been reported on optimizing the position the PVDF nasal sensor with respect to human nose. Chapter 5 This chapter is divided into two sections, Section 5.1: This section describes the applicability of the PVDF nasal sensor using its piezoelectric property to monitor the human respiration pattern of each nostril simultaneously. The results of the PVDF nasal sensor have also been evaluated by comparing with Respiratory Inductive Plethysmograph(RIP) technique in normal subjects. Section 5.2: In this section, PVDF nasal sensor, RIP and Nasal Prongs (NP) techniques were used to measure the RR of healthy adults. The aim here was to evaluate the presently developed PVDF nasal sensor for identifying different RR compared to „Gold standard‟ RIP and NP methods. Chapter 6 This chapter is divided into two sections. Section 6.1: This section reports about the utilization of the developed PVDF nasal sensor for clinical application on the patient population. For this purpose, the performance of the PVDF nasal sensor measurements has been compared with the Peak Nasal Inspiratory Flow(PNIF) objective technique and visual analog scale (VAS). Section 6.2: This section describes about the use of PVDF nasal sensor system to measure nasal obstruction caused due to DNS objectively. Further, the results of the PVDF nasal sensor were compared with subjective techniques namely, VAS and clinician scale in patients and control group. Chapter 7 This chapter is composed of two sections. Section 7.1: This section summarizes the salient features of the work presented in this thesis. Section 7.2: This section reports a scope for carrying out further work.

The growth of sensors and sensing technologies have made significant impact in our day-to-day life. The five principle sensory organs of our body should perform effectively, so that we can lead a good healthy life. Apart from these natural sensors, there are man-made sensors that helps us to cope with diseases, organ failure etc. and enable us to lead a normal life. In recent years, with the prevalence of new kind of diseases, the need for new type of biomedical sensors is becoming very important. As a result, sensors used for biomedical applications have become an emerging technology and rapidly growing field of research. The aim of the present thesis work is to use the piezoelectric property of Polyvinylidene Fluoride (PVDF) film for the development of biomedical sensor and studying its application for human respiration/breathing related abnormalities. PVDF nasal sensor was designed in cantilever configuration and detailed theoretical analysis of the same was performed. Based on theoretical and experimental results, the PVDF nasal sensor dimensions were optimized. Suitable signal conditioning circuitry was designed and a measurement system for biomedical application was developed. The developed PVDF nasal sensor was calibrated using MEMS low-pressure sensor. The PVDF nasal sensor system has been applied in different biomedical applications namely, (i) to monitor human respiration pattern, (ii) to identify different Respiration Rates (RR), (iii) to evaluate Deviated Nasal Septum (DNS) in comparison with other objective method and, (vi) to clinically investigate nasal obstruction in comparison with subjective method. The thesis is divided into seven chapters. Chapter 1 This chapter gives a general introduction about biomedical sensors, piezoelectric sensing principle and PVDF polymer films along with the relevant literature survey. The brief introduction as well as literature survey of techniques used to monitor human respiration and to measure nasal obstruction is also included in this chapter. Chapter 2 This chapter gives details about the design of the PVDF nasal sensor in the cantilever configuration for sensing nasal airflow along with the relevant theoretical equations. Also, the details on the optimization of the PVDF nasal sensor dimensions based on the theoretical and experimental analysis are presented. Chapter 3 This chapter reports the designing of the necessary signal conditioning hardware along with the data acquisition unit for the PVDF nasal sensor. The signal conditioning hardware unit made consists of charge amplifier, low-pass filter and an amplifier. Besides, a complete measurement system for biomedical application was developed using PVDF nasal sensor and its merits and demerits were discussed. Chapter 4 In this chapter, an experimental set-up for measuring human respiration/breathing pressure using water U-tube manometer has been described. Also, the calibration procedure followed for the developed PVDF nasal sensor using a Micro Electro Mechanical Systems(MEMS) low pressure sensor is reported. Apart from these, the details on the measurement of deflection of the PVDF cantilever sensing element using laser displacement setup are provided. In addition, the PVDF nasal sensor was also calibrated for various air flow rates. At the end, a study has been reported on optimizing the position the PVDF nasal sensor with respect to human nose. Chapter 5 This chapter is divided into two sections, Section 5.1: This section describes the applicability of the PVDF nasal sensor using its piezoelectric property to monitor the human respiration pattern of each nostril simultaneously. The results of the PVDF nasal sensor have also been evaluated by comparing with Respiratory Inductive Plethysmograph(RIP) technique in normal subjects. Section 5.2: In this section, PVDF nasal sensor, RIP and Nasal Prongs (NP) techniques were used to measure the RR of healthy adults. The aim here was to evaluate the presently developed PVDF nasal sensor for identifying different RR compared to „Gold standard‟ RIP and NP methods. Chapter 6 This chapter is divided into two sections. Section 6.1: This section reports about the utilization of the developed PVDF nasal sensor for clinical application on the patient population. For this purpose, the performance of the PVDF nasal sensor measurements has been compared with the Peak Nasal Inspiratory Flow(PNIF) objective technique and visual analog scale (VAS). Section 6.2: This section describes about the use of PVDF nasal sensor system to measure nasal obstruction caused due to DNS objectively. Further, the results of the PVDF nasal sensor were compared with subjective techniques namely, VAS and clinician scale in patients and control group. Chapter 7 This chapter is composed of two sections. Section 7.1: This section summarizes the salient features of the work presented in this thesis. Section 7.2: This section reports a scope for carrying out further work.

Vehicular bumper is a structure mounted at the front and rear of the vehicle to absorb the first impact and is designed to minimize its effect on the vehicle structure and its occupants. Although vehicle collision is an unavoidable fact, there are no reported attempts to date in exploring the feasibility of detection system utilizing sensors. For this investigation, PVDF (Polyvinylidene Fluoride) sensor for its sensitivity and dynamic range is selected for application to bumpers. A prototype bumper with PVDF sensors is fabricated to carry out tests under low level forces. A prototype bumper represented by a Plexiglass beam is mounted with a series of PVDF sensors across the length, while the bumper is mounted on a rigid structure through set of mounts. Each sensor is calibrated for various loads on and away from the sensor and tested to predict the magnitude of the force and corresponding position. Several configurations for the bumper with and without cover over the sensor surface are experimented to determine the collision detection capability of the bumper in terms of magnitude, duration and location of the impact. The time history response of each sensor and its characteristics are utilized to develop layouts for bumper systems with sensors. Two designs were fabricated and tested in the laboratory to establish methodology for establishing relationships between sensor responses with magnitude and location of collision. Based on the investigation, a final design is proposed for implementation of collision detection in automotive bumpers.

Mechanical vibrations in large structures such as buildings, bridges, dams and critical frequencies in large machinery generally have low frequencies (100Hz-1000Hz). To monitor large areas of such structures we need huge network of low cost, easily manufacturable, self-powered and stand-alone vibration spectrum sensors. The sensors should also consume very little power during their overall operation cycle and have moderately high frequency resoultion. The thesis provides mathematical analysis, design and development of stand-alone, low frequency vibration spectrum analyzer .A mechanically stretched polymer piezoelectric membrane, which has a fixed length and tension, can act as a single frequency detector due to its unique resonant frequency. Stretching multiple ribbons of diffferent lengths and tensions, a vibration spectrum analyzer, which gives the Fourier frequency components present in an arbitrary mechanical input vibration, can be designed. The thesis presents a detailed description of experiments to evaluate a low frequency vibration spectrum analyzer system that accepts an incoming input vibration and directly provides the spectrum as output. Polymer piezoelectric materials being easily manufacturable these sensors can be deployed in wide area sensor networks that monitor large structures. The thesis also shows design of a vibration energy harvesting system based on the concept of harvesting energy at low frequencies. The need for developing such an energy harvesting system arises from the necessity of making the vibration sensor, self-powered. Multiple experimental tests were performed before developing a prototype vibration energy harvesting circuit.

Mechanical vibrations in large structures such as buildings, bridges, dams and critical frequencies in large machinery generally have low frequencies (100Hz-1000Hz). To monitor large areas of such structures we need huge network of low cost, easily manufacturable, self-powered and stand-alone vibration spectrum sensors. The sensors should also consume very little power during their overall operation cycle and have moderately high frequency resoultion. The thesis provides mathematical analysis, design and development of stand-alone, low frequency vibration spectrum analyzer .A mechanically stretched polymer piezoelectric membrane, which has a fixed length and tension, can act as a single frequency detector due to its unique resonant frequency. Stretching multiple ribbons of diffferent lengths and tensions, a vibration spectrum analyzer, which gives the Fourier frequency components present in an arbitrary mechanical input vibration, can be designed. The thesis presents a detailed description of experiments to evaluate a low frequency vibration spectrum analyzer system that accepts an incoming input vibration and directly provides the spectrum as output. Polymer piezoelectric materials being easily manufacturable these sensors can be deployed in wide area sensor networks that monitor large structures. The thesis also shows design of a vibration energy harvesting system based on the concept of harvesting energy at low frequencies. The need for developing such an energy harvesting system arises from the necessity of making the vibration sensor, self-powered. Multiple experimental tests were performed before developing a prototype vibration energy harvesting circuit.

Perfluoroalkyl substances (PFAS) are a class of man-made chemicals with many uses from fire-fighting foams to surface coatings and other industrial applications. In recent years, PFAS have gained considerable attention within the scientific community and the global media alike. Due to their strong chemical bonds, PFAS are inherently non-biodegradable and therefore persist in the environment. Listed in the Stockholm Convention of Persistent Organic Pollutants, these chemicals have been linked to various health issues in both humans and animals, lately, which are resulting in millions of dollars’ worth of expenses in health care and compensation for the governments of affected countries every year. In addition, the cost of cleaning up PFAS from the environment along with these human costs exceeds $50 billion in Europe alone. There is an urgent need for a portable sensing system to detect PFAS in the environment, including the most common types, perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS). At present, the methods available to accurately measure the concentration of PFAS in contaminated samples involve field sampling followed by laboratory-based, time consuming analytical techniques, such as liquid/gas chromatography and tandem mass spectrometry that are unsuitable for real-time field measurements. Existing portable systems have not yet attained the precision of the analytical methods and face challenges in field tests due to various limitations, including lack of specificity, cross sensitivity to environmental conditions and generation of toxic waste. Therefore, this research has focused on providing a proof of principle of a Fabry- Perot Interferometry (FPI) based optical fibre sensor for in situ detection of PFOA in aqueous solution. It has aimed at characterizing the potential of the envisioned PFAS sensing technique to obtain accurate and real time measurements. The proposed research capitalised on the numerous practical advantages offered by optical fibre sensors and the ability of an integrated polyvinylidene fluoride (PVDF) coating at the fibre end-face to respond to the presence of PFOA. To the best of the author’s knowledge, PVDF was experimentally shown to respond to the emerging contaminants for the first time in this work. A novel approach of forming a thin PVDF film (or Fabry-Perot etalon) on an optical fibre end-face was developed and thoroughly characterized. The thermoplastic polymer PVDF, known for its many useful characteristics such as hydrophobicity, corrosion resistance and ferroelectricity, was considered a robust sensor material based on its performance related to water filtration membranes and other engineering applications. This work has reported the synthesis of optimized coating on optical fibres through the immersion precipitation technique and has discussed subsequent experiments with the fabricated PFAS detector that demonstrated reproducible changes in the FPI spectrum in the presence of PFOA. Successful detection of analytes or their change in concentration was denoted by spectral shifts on the obtained FPI reflection spectra. A variation in the optical path difference (OPD) determined through numerical modelling provided a measure of sensitivity of the FPI based system to the different PFOA solutions. Analytical tests confirmed that PVDF adsorbs PFOA by measuring the concentration of PFOA in solution before and after a PVDF film was immersed for several hours. Visual evidence in the form of scanning electron microscopic images also displayed differences in the surface structures of PVDF thin films that were exposed to PFOA. These results supported the inference that the changes in OPD were due to the adsorption of PFOA on the PVDF coated optical fibre. In addition to the solutions containing known amounts of PFOA, real industrial solutions containing residual fire-fighting foam from fire trucks were tested and showed successful detection at low levels. In this case, the solutions contained a mixture of PFOA and PFOS with a range of other PFAS compounds that are typically used in these foam formulations. Further investigation involving alternative optical methods employing refractive index- based measurement utilizing an etched fibre Bragg grating (EFBG) and also a bare optical fibre, showed spectral response to change in PFOA concentration in solution. A shift in the EFBG spectrum due to change in PFOA concentration in the solution in which PVDF membranes had been soaked indicated that the analyte was adsorbed by the polymer. Similarly, a change in the reflection intensity of the signal obtained by a bare fibre end-face in the PFOA solution due to a change in its refractive index, indicated the adsorption of the fluoro surfactant on the PVDF thin film. Following the confirmation of PFOA uptake by PVDF, functionalization of the polymer was also investigated, which revealed that the incorporation of zeolites into PVDF enables more PFOA from aqueous solution to be adsorbed onto the thin film. Fourier transform infrared spectroscopy was used to highlight structural differences in the doped coatings, whereas energy dispersive x-ray spectroscopy was used to show compositional differences between the doped and non-doped PVDF thin films. Thus, this research contributed to the prospect of developing a functionalized sensor for more efficient detection of PFAs while also creating opportunities for further research in water treatment. A temperature characterization test, which was undertaken to eliminate possible signal cross-sensitivity effects, also indicated that the PVDF coated fibre can be considered for thermometric applications due to its good repeatability and linearity of the measurements over a specified temperature range. More importantly, information gathered from the undertaken characterization test was used to optimize the PFOA sensing protocol in order to obtain reliable results. This research has provided experimental evidence to support that a PVDF coated optical fibre can be used as a potential portable PFAS detector. It has demonstrated a novel and simple thin film fabrication and optimization process for selective detection of the emerging contaminant PFOA. Furthermore, by combining an interferometry type optical fibre sensing technology with aqueous PFAS detection this research has established the foundation for future studies that can lead to commercialisation of a portable PFAS sensor for wide-ranging environmental and engineering applications.

The main thrust of this thesis is the development of new triarylborane containing luminescent molecules as well as utilizing triarylboron center as a receptor for the selective detection of biologically, environmentally and industrially important anions such as fluoride and cyanide in aqueous and non-aqueous solutions. The thesis contains nine chapters. The contents of each chapter are described below. Chapter 1 The first chapter is an introduction to the theme of the thesis and presents a general review on the techniques, theories and photochemistry relevant to the present work with emphasis on photochemistry of triarylboranes and their importance in the field of anion sensor chemistry. A review on various boron based luminophores is also presented. Chapter 2 The second chapter deals with the general experimental techniques and synthetic procedures utilized in this work. Chapter 3 This chapter deals with the synthesis of boryl-BODIPY dyads (1-8) in which triarylborane acts as anion receptor and BODIPY as a signalling unit. The absorption spectra of all boryl-BODIPY dyads shows similar pattern. However, the fluorescence spectra of 1, 2, 3, 6 and 7 shows dual emission bands whereas 4, 5 and 8 exhibit a single emission band. These interesting photophysical properties of boryl-BODIPYs (1-8) depends on the dihedral angle between two chromophores and partial energy transfer from donor (triarylborane) to acceptor (BODIPY) unit. The energy transfer efficiency of compounds 4, 5 and 8 is higher (close to 100%) compared to other series of boryl-BODIPYs (1-3, 6 and 7), due to the orthogonal arrangement of chromophores with high dihedral angles. To better understand photophysical properties and energy transfer process, anion binding studies were carried out since triarylborane acts as receptor for fluoride and cyanide ions. Anion binding studies of boryl-BODIPYs were (1-5) carried out in dichloromethane solutions and using tetrabutylammonium salt of fluoride/cyanide. All boryl-BODIPY dyads (1-5) were sensitive and selective sensor of fluoride, whereas the presence of only excess amounts (20 equv or more amounts) of cyanide made any changes in absorption and emission spectra. Other anions even above 100 eq were unable to cause any change. The quenching efficiency of compounds 4 and 5 was found to be more than that of other boryl-BODIPYs (1 and 3). The binding of fluoride with boryl-BODIPY (1-5) was entirely reversible; addition of BF3•Et2O to the fluoride adducts of compounds (1-5) regenerated the parent compounds. Chapter 4 In chapter 3, it was established that linear boryl-BODIPY dyads (1-8) show dual/single fluorescence bands depending on the dihedral angle between triarylborane and BODIPY unit. This Chapter describes the synthesis of three new “V” shaped boryl-BODIPY dyads (9, 10 and 11) their optical properties, Compound 9-11 are structurally similar differing only in the number of methyl substituents on the BODIPY moiety which were found to play major role in determining their optical behavior. The dyads show rare forms of multiple channel emission characteristics arising from different extents of electronic energy transfer (EET) processes between the two covalently linked fluorescent chromophores (triarylborane and BODIPY units). Owing to the presence of Lewis acidic triarylborane moiety, the dyads function as highly selective and sensitive fluoride sensors with vastly different response behavior. Upon binding of fluoride to the tricoordinate borane centre, dyad 9 shows gradual quenching of its BODIPY dominated emission due to the cessation of (borane to BODIPY) EET process. Dyad 10 shows ratiometric changes in its emission behavior upon addition of fluoride. Dyad 11 forms fluoride induced nanoaggregates which result in fast and effective quenching of its emission intensity upon addition of even small quantities of analyte (i.e. 0.1 equivalent of fluoride). When the solution is allowed to stand, disaggregation of the molecules results in partial recovery of the initial fluorescence bands. Thus, small structural alterations in these three structurally close dyads (9-11) result in exceptionally versatile and unique photophysical behavior and remarkably diverse responses towards a single analyte i.e. fluoride anion. Chapter 5 This chapter deals with intermolecular charge transfer (ICT) process in borane containing donor-acceptor triads and tetrads to realize colorimetric response for small anions such as fluoride and cyanide. Triad 12 and tetrad 13 incorporating –B(Mes)2, BDY (borondipyrromethene), and TPA (triphenylamine) were synthesized. Introduction of two dissimilar acceptors (triarylborane and BODIPY) on a single donor (TPA) resulted in two distinct ICT process (amine to borane and amine to BDY). The absorption and emission properties of new triad and tetrad are highly dependent on individual building units. The nature of electronic communication among the individual fluorophore units has been comprehensively investigated and compared with building units. Compounds 12 and 13 showed chromogenic and fluorogenic response towards small anions such as fluoride and cyanide. Chapter 6 In the previous chapter, it was demonstrated that although triphenylamine-triarylborane-BODIPY donor-acceptor conjugates show colorimetric response towards fluoride and cyanide. They could not distinguish these two interfering anions. To overcome the anion interference peripherally triarylborane decorated porphyrin (14) and its Zn(II) complex (15) were designed and synthesized and this forms the subject matter of this Chapter. Compound 15 contains two different Lewis acidic binding sites (Zn(II) and boron centre). Unlike all previously known triarylborane based sensors, the optical responses of 15 towards fluoride and cyanide are distinctively different thus enabling the discrimination of these two interfering anions. Metalloporphyrin 15 shows a multiple channel fluorogenic response towards fluoride and cyanide and also a selective visual colorimetric response towards cyanide. By comparison with model systems and from detailed photophysical studies on 14 and 15, it was concluded that the preferential binding of fluoride occurs at the peripheral borane moieties resulting in the cessation of the EET (electronic energy transfer) process from triarylborane to porphyrin core and with negligible negative cooperative effects. On the other hand, cyanide binding occurs at the Zn(II) core leading to drastic changes in its absorption behavior which can be followed by the naked eye. Such changes are not observed when the boryl substituent is absent (e.g. tetraphenyl-Zn(II)-porphyrin or TPP). The conjugates 14 and 15 showed reversible binding interaction towards CN and F and they are capable of extracting fluoride from aqueous media. Chapter 7 This Chapter deals with the design of a sensor which can detect fluoride colorimetrically in aqueous medium. Detecting fluoride in aqueous solution is an important area of current research owing to both positive and negative health and environmental effects associated with the fluoride ion. Although numerous fluoride sensors are reported, the colorimetric sensing (visual detection without the need of costly equipment and complicated analytical of fluoride at recommended levels 0.7 ppm) has not realized. Here we report the design, optical and fluoride sensing ability of two new water soluble Lewis acidic triarylborane-triarylamine conjugates 16 and 17 (containing one or two ammonium cations (-C6H4-NMe3). Compound 17 shows selective colorimetric response for aqueous inorganic fluoride at as low a level as 0.1 ppm Chapter 8 The synthesis and optical properties of four new triarylborane–dipyrromethane (TAB– DPM) conjugates (19a–d) containing dual binding sites (hydrogen bond donor and Lewis acid) have been reported. The new compounds exhibit a selective fluorogenic response towards the F− ion. The NMR titrations show that the fluoride ions bind to the TAB–DPM conjugates via the Lewis acidic triarylborane centre in preference to the hydrogen bond donor (dipyrromethane) units. Chapter 9 A new triarylborane-aza-BODIPY conjugate is reported (22). The conjugate molecule consists of two blue emissive dimesitylarylborane moiety and a NIR (near infra-red) emissive aza-BOIDPY core and shows panchromatic absorption spanning over ~300-800 nm region. The presence of two different fluorophore units in the conjugate leads to a broad dual-emissive feature covering a large part of visible and NIR region. DFT computational studies suggest limited electronic communication between the individual fluorophore units which may be responsible for the intriguing optical features of the conjugate molecule. Further, the broadband emissive conjugate can act as a selective sensor for fluoride anion as a result of fluorescence quenching response in both visible as well as in NIR spectral region.

The main thrust of this thesis is the development of new triarylborane containing luminescent molecules as well as utilizing triarylboron center as a receptor for the selective detection of biologically, environmentally and industrially important anions such as fluoride and cyanide in aqueous and non-aqueous solutions. The thesis contains nine chapters. The contents of each chapter are described below. Chapter 1 The first chapter is an introduction to the theme of the thesis and presents a general review on the techniques, theories and photochemistry relevant to the present work with emphasis on photochemistry of triarylboranes and their importance in the field of anion sensor chemistry. A review on various boron based luminophores is also presented. Chapter 2 The second chapter deals with the general experimental techniques and synthetic procedures utilized in this work. Chapter 3 This chapter deals with the synthesis of boryl-BODIPY dyads (1-8) in which triarylborane acts as anion receptor and BODIPY as a signalling unit. The absorption spectra of all boryl-BODIPY dyads shows similar pattern. However, the fluorescence spectra of 1, 2, 3, 6 and 7 shows dual emission bands whereas 4, 5 and 8 exhibit a single emission band. These interesting photophysical properties of boryl-BODIPYs (1-8) depends on the dihedral angle between two chromophores and partial energy transfer from donor (triarylborane) to acceptor (BODIPY) unit. The energy transfer efficiency of compounds 4, 5 and 8 is higher (close to 100%) compared to other series of boryl-BODIPYs (1-3, 6 and 7), due to the orthogonal arrangement of chromophores with high dihedral angles. To better understand photophysical properties and energy transfer process, anion binding studies were carried out since triarylborane acts as receptor for fluoride and cyanide ions. Anion binding studies of boryl-BODIPYs were (1-5) carried out in dichloromethane solutions and using tetrabutylammonium salt of fluoride/cyanide. All boryl-BODIPY dyads (1-5) were sensitive and selective sensor of fluoride, whereas the presence of only excess amounts (20 equv or more amounts) of cyanide made any changes in absorption and emission spectra. Other anions even above 100 eq were unable to cause any change. The quenching efficiency of compounds 4 and 5 was found to be more than that of other boryl-BODIPYs (1 and 3). The binding of fluoride with boryl-BODIPY (1-5) was entirely reversible; addition of BF3•Et2O to the fluoride adducts of compounds (1-5) regenerated the parent compounds. Chapter 4 In chapter 3, it was established that linear boryl-BODIPY dyads (1-8) show dual/single fluorescence bands depending on the dihedral angle between triarylborane and BODIPY unit. This Chapter describes the synthesis of three new “V” shaped boryl-BODIPY dyads (9, 10 and 11) their optical properties, Compound 9-11 are structurally similar differing only in the number of methyl substituents on the BODIPY moiety which were found to play major role in determining their optical behavior. The dyads show rare forms of multiple channel emission characteristics arising from different extents of electronic energy transfer (EET) processes between the two covalently linked fluorescent chromophores (triarylborane and BODIPY units). Owing to the presence of Lewis acidic triarylborane moiety, the dyads function as highly selective and sensitive fluoride sensors with vastly different response behavior. Upon binding of fluoride to the tricoordinate borane centre, dyad 9 shows gradual quenching of its BODIPY dominated emission due to the cessation of (borane to BODIPY) EET process. Dyad 10 shows ratiometric changes in its emission behavior upon addition of fluoride. Dyad 11 forms fluoride induced nanoaggregates which result in fast and effective quenching of its emission intensity upon addition of even small quantities of analyte (i.e. 0.1 equivalent of fluoride). When the solution is allowed to stand, disaggregation of the molecules results in partial recovery of the initial fluorescence bands. Thus, small structural alterations in these three structurally close dyads (9-11) result in exceptionally versatile and unique photophysical behavior and remarkably diverse responses towards a single analyte i.e. fluoride anion. Chapter 5 This chapter deals with intermolecular charge transfer (ICT) process in borane containing donor-acceptor triads and tetrads to realize colorimetric response for small anions such as fluoride and cyanide. Triad 12 and tetrad 13 incorporating –B(Mes)2, BDY (borondipyrromethene), and TPA (triphenylamine) were synthesized. Introduction of two dissimilar acceptors (triarylborane and BODIPY) on a single donor (TPA) resulted in two distinct ICT process (amine to borane and amine to BDY). The absorption and emission properties of new triad and tetrad are highly dependent on individual building units. The nature of electronic communication among the individual fluorophore units has been comprehensively investigated and compared with building units. Compounds 12 and 13 showed chromogenic and fluorogenic response towards small anions such as fluoride and cyanide. Chapter 6 In the previous chapter, it was demonstrated that although triphenylamine-triarylborane-BODIPY donor-acceptor conjugates show colorimetric response towards fluoride and cyanide. They could not distinguish these two interfering anions. To overcome the anion interference peripherally triarylborane decorated porphyrin (14) and its Zn(II) complex (15) were designed and synthesized and this forms the subject matter of this Chapter. Compound 15 contains two different Lewis acidic binding sites (Zn(II) and boron centre). Unlike all previously known triarylborane based sensors, the optical responses of 15 towards fluoride and cyanide are distinctively different thus enabling the discrimination of these two interfering anions. Metalloporphyrin 15 shows a multiple channel fluorogenic response towards fluoride and cyanide and also a selective visual colorimetric response towards cyanide. By comparison with model systems and from detailed photophysical studies on 14 and 15, it was concluded that the preferential binding of fluoride occurs at the peripheral borane moieties resulting in the cessation of the EET (electronic energy transfer) process from triarylborane to porphyrin core and with negligible negative cooperative effects. On the other hand, cyanide binding occurs at the Zn(II) core leading to drastic changes in its absorption behavior which can be followed by the naked eye. Such changes are not observed when the boryl substituent is absent (e.g. tetraphenyl-Zn(II)-porphyrin or TPP). The conjugates 14 and 15 showed reversible binding interaction towards CN and F and they are capable of extracting fluoride from aqueous media. Chapter 7 This Chapter deals with the design of a sensor which can detect fluoride colorimetrically in aqueous medium. Detecting fluoride in aqueous solution is an important area of current research owing to both positive and negative health and environmental effects associated with the fluoride ion. Although numerous fluoride sensors are reported, the colorimetric sensing (visual detection without the need of costly equipment and complicated analytical of fluoride at recommended levels 0.7 ppm) has not realized. Here we report the design, optical and fluoride sensing ability of two new water soluble Lewis acidic triarylborane-triarylamine conjugates 16 and 17 (containing one or two ammonium cations (-C6H4-NMe3). Compound 17 shows selective colorimetric response for aqueous inorganic fluoride at as low a level as 0.1 ppm Chapter 8 The synthesis and optical properties of four new triarylborane–dipyrromethane (TAB– DPM) conjugates (19a–d) containing dual binding sites (hydrogen bond donor and Lewis acid) have been reported. The new compounds exhibit a selective fluorogenic response towards the F− ion. The NMR titrations show that the fluoride ions bind to the TAB–DPM conjugates via the Lewis acidic triarylborane centre in preference to the hydrogen bond donor (dipyrromethane) units. Chapter 9 A new triarylborane-aza-BODIPY conjugate is reported (22). The conjugate molecule consists of two blue emissive dimesitylarylborane moiety and a NIR (near infra-red) emissive aza-BOIDPY core and shows panchromatic absorption spanning over ~300-800 nm region. The presence of two different fluorophore units in the conjugate leads to a broad dual-emissive feature covering a large part of visible and NIR region. DFT computational studies suggest limited electronic communication between the individual fluorophore units which may be responsible for the intriguing optical features of the conjugate molecule. Further, the broadband emissive conjugate can act as a selective sensor for fluoride anion as a result of fluorescence quenching response in both visible as well as in NIR spectral region.

In this thesis, the results pertaining to various investigations carried out on Triglycine sulphate (TGS) single crystals, polyvinylidene fluoride (PVDF) films, lithium tantalate (LT)/PVDF nanocomposites and LT thin films are presented with emphasis on the characteristics that are crucial for their use in pyroelectric sensors. TGS single crystals (size 68 x 45 x 42 mm3), which have high pyroelectric coefficients, were grown by slow cooling method using newly designed platform technique based crystal growth work stations. The problem of slow growth rate along c-direction was overcome by placing (010) oriented seeds on the platform. The grown TGS crystals were used for the fabrication of the laser energy meter and temperature sensor. One drawback of TGS is its low Curie temperature (490C). As a consequence when the operating temperature approaches the Curie temperature, the crystals start depolarizing owing to the movement of domains. As a result the linearity of the devices gets affected and restricts the use of TGS. Therefore pyroelectric materials possessing higher Curie temperatures and larger pyroelectric coefficients than that of TGS are desirable. LT in single crystalline form having Curie temperature of ≈6000C has already been in use for pyroelectric device applications. However, growing stoichiometric LT single crystal is very difficult. On the other hand PVDF polymer films (Tc≈1800C) have low pyrolectric coefficients and difficult to pole electrically. Therefore efforts were made to prepare LT/PVDF nanocrystal composites to increase the pyroelectric coefficient of PVDF and to reduce the poling field. Nanoparticles of LT were prepared using sol-gel route. Spherical nanoparticles of size 20-40nm were prepared from sol by adding oleic acid to it. These nanoparticles were characterized using XRD, TEM, DSC and Raman spectroscopy. PVDF films with large percentage of β-phase (ferroelectric phase) were fabricated from solutions prepared using dimethylsulphoxide (DMSO) solvent. PVDF films (30µm thick), embedded with 20-40nm sized nanocrystallites of LT were fabricated to utilize them for pyroelectric sensor applications. The ferroelectric and pyrolectric properties of nano composite films were studied for sensor applications point of view. As a replacement for the single crystals of LT in pyroelectric sensors, investigations were carried out on oriented LT thin films. The studies on LT thin films yielded promising results which could be exploited for pyroelectric sensor applications.

In this thesis, the results pertaining to various investigations carried out on Triglycine sulphate (TGS) single crystals, polyvinylidene fluoride (PVDF) films, lithium tantalate (LT)/PVDF nanocomposites and LT thin films are presented with emphasis on the characteristics that are crucial for their use in pyroelectric sensors. TGS single crystals (size 68 x 45 x 42 mm3), which have high pyroelectric coefficients, were grown by slow cooling method using newly designed platform technique based crystal growth work stations. The problem of slow growth rate along c-direction was overcome by placing (010) oriented seeds on the platform. The grown TGS crystals were used for the fabrication of the laser energy meter and temperature sensor. One drawback of TGS is its low Curie temperature (490C). As a consequence when the operating temperature approaches the Curie temperature, the crystals start depolarizing owing to the movement of domains. As a result the linearity of the devices gets affected and restricts the use of TGS. Therefore pyroelectric materials possessing higher Curie temperatures and larger pyroelectric coefficients than that of TGS are desirable. LT in single crystalline form having Curie temperature of ≈6000C has already been in use for pyroelectric device applications. However, growing stoichiometric LT single crystal is very difficult. On the other hand PVDF polymer films (Tc≈1800C) have low pyrolectric coefficients and difficult to pole electrically. Therefore efforts were made to prepare LT/PVDF nanocrystal composites to increase the pyroelectric coefficient of PVDF and to reduce the poling field. Nanoparticles of LT were prepared using sol-gel route. Spherical nanoparticles of size 20-40nm were prepared from sol by adding oleic acid to it. These nanoparticles were characterized using XRD, TEM, DSC and Raman spectroscopy. PVDF films with large percentage of β-phase (ferroelectric phase) were fabricated from solutions prepared using dimethylsulphoxide (DMSO) solvent. PVDF films (30µm thick), embedded with 20-40nm sized nanocrystallites of LT were fabricated to utilize them for pyroelectric sensor applications. The ferroelectric and pyrolectric properties of nano composite films were studied for sensor applications point of view. As a replacement for the single crystals of LT in pyroelectric sensors, investigations were carried out on oriented LT thin films. The studies on LT thin films yielded promising results which could be exploited for pyroelectric sensor applications.

Minimally invasive surgery (MIS) procedures have been growing rapidly for the past couple of decades. In MIS operations, endoscopic tools are inserted through a small incision on human's body. Although these procedures have many advantages such as fast recovery time, minimum damage to human body and reduced post operative complications, it does not provide any tactile feedback to the surgeon. This thesis reports on design, finite element analysis, fabrication and testing of a micromachined piezoelectric endoscopic tactile sensor. Similar to the commercial endoscopic graspers, the sensor is teeth like in order to grasp slippery tissues. It consists of three layers; the first layer is a silicon layer of teeth shapes on the top and two supports at the bottom forming a thin plate and a U-Channel. The second layer is a patterned Polyvinylidene Fluoride (PVDF) film, and the third layer is a supporting Plexiglas. The patterned PVDF film was placed on the middle between the other two layers. When a concentric load is applied to the sensor, the magnitude and the position of the applied load are obtained from the outputs of the sensing elements which are sandwiched between the silicon supports and the Plexiglas. In addition, when a soft object/tissue is place on the sensor and load is applied the degree of the softness/compliance of the object is obtained from the outputs from the middle PVDF sensing elements, which are glued to the back of the thin silicon plate. The outputs are related to the deformation of the silicon plate which related to the contacting object softness. The sensor has high sensitivity and high dynamic range as a result it can potentially detect a small dynamic load such as a pulse load as well as a high load such as a firm grasping of a tissue by an endoscopic grasper. The entire surface of the tactile sensor is also active, which is an advantage in detecting the precise position of the applied point load on the grasper. The finite element analysis and experimental results are in close agreement with each other. The sensor can potentially be integrated with the gasper of a commercially available endoscopic grasper

Promising results of Minimally Invasive Surgery, MIS, in the last two decades have been the main incentive of numerous researches in this area. However, despite numerous advantages of this relatively new technique, using of long tools inserted through small ports on the body deprive surgeons of the depth perception, dexterity, sense of touch, and straightforward hand-eye coordination that are accustomed to surgeons in open procedures. Many researches have been launched to rectify the mentioned shortcomings and some improvements, such as, excellent stereo visual feedback and satisfactory dexterity, have been made recently in robotic assisted surgical systems. However, the current MIS tools whether in endoscopic surgery or in robotic assisted surgery are incapable of providing tactile feedback. The tactile information collected by the surgeon's hand in an open surgery is vital for success in complex and delicate operations. For instance, the ability to distinguish between different types of tissue in the body is of vital importance to a surgeon. Before making an incision into tissue, the surgeon must identify what type of tissue is being incised. Failure to classify properly the tissue can cause severe consequences. There have been some attempts to develop smart MIS graspers with integrated sensors. However, many of these integrated sensors are limited to force or softness sensing. From a functional point of view, integrating several sensors each of them is responsible for measuring a specific quantity is difficult. In contrast, a multi-functional tactile sensor which would be able to address several concerns such as force measurement, determining position of the force, assessing softness of the grasped object, detecting any hidden lumps in bulk soft tissue is highly desirable. The transduction techniques used in the relevant researches have been reported as capacitive and piezoelectric techniques. In this study, the piezoelectric polymer Polyvinylidene Fluoride (PVDF) has been used as the transducer due to its unique features and also bio-compatibility. This study aimed at introducing a multi-functional tactile sensor which would be able to address many of the required information in a surgery procedure. A unit of the proposed sensor is able to measure the applied force and its position along the length of the sensor system. In addition, it is also able to differentiate the softness of the contact objects. An array of sensor is able to locate the applied load or any hidden mass in a plane (i.e. xy plane). Integration of the sensors into both jaws of the grasper, enables the smart grasper to determine the depth of any hidden masses. Regardless of the type of the integrated sensor, the study of stress profile in the presence of a lump, at the contact surface of object-grasper is of importance. The behavior of the soft tissue highly influences the stress distribution at the contact surface of tissue and grasper. Although modeling all of the complex behavior of soft tissue is very difficult, in this study, the nonlinear characteristics of the tissue is considered. In the absence of the soft tissue the simulation and experiments are conducted on the elastomers which exhibit very similar behavior. However, the ultimate objective is the integration of the proposed sensor with the existing MIS graspers. To do this, the sensor must be microfabricated. Therefore, in order to study the feasibility of micromachining of the proposed sensor, the microfabrication procedure for the tactile sensor was examined and the fabrication difficulties were identified. The conventional anisotropic wet etching has been used for micromachining the device.

碩士
國立成功大學
化學工程學系碩博士班
90
Abstract The preparation of Pt/LaF3/Pt assembly and its sensing characteristics of oxygen and carbon monoxide at room temperature were studied in this research. It is our objective to develop carbon monoxide sensor operated at room temperature. Sensing behavior and mechanism for carbon monoxide with and without oxygen were also discussed. Parameters including flow rate, loading pressure on LaF3 pellet, and concentration of oxygen affected sensitivity. In this thesis, Tafel plot was proposed to describe the sensing mechanism. LaF3 powder was pressed to form a pellet by different loading pressures from 1.8 to 4.4 ton/cm2, and then sintered at 700 ºC for 7 hr. When loading pressure on LaF3 powder was increased, porosity of pellet decreased from 7.52×10-3 to 4.73×10-3and LaF3 phase also increased. Increasing LaF3 phase can improve ionic conduction of the electrolyte. In addition, the surface roughness on sensing electrode decreased due to higher loading pressure. From cyclic voltammogram, the change of charge for hydrogen oxidation revealed that real surface area decreased with the loading pressure increasing. Using Pt/LaF3/Pt assembly for sensing oxygen, sensitivity decreased from 49.2 to 28.7 mV/decade and the corresponding number of electron transfer increased from 1.2 to 2.1 when gas flow rate increased from 50 to 80 ml/min. The response time decreased to 11.7 min with gas flow rate increasing to 80 ml/min. The effect of gas flow rate on sensing potential difference for carbon monoxide without oxygen could be neglected. Sensitivity for carbon monoxide was 66 mV/min, and the calculated number of electron transfer was 0.9.When carbon monoxide existed, the sensing potential difference decreased with increasing oxygen concentration. The sensitivity for carbon monoxide decreased significantly down to 25.9 mV/decade when oxygen concentration was up to 40 %. Loading pressure influenced the sensitivity for sensing oxygen, and carbon monoxide with and without oxygen. There was an optimum loading pressure for a maximum sensitivity. The sensing potential difference, the mixed potential subtracting from equilibrium potential of oxygen in Tafel plot, for carbon monoxide in the presence of oxygen corresponded to that measured by open circuit potential. In addition, the proposed Tafel plot was reasonable for explaining the sensing potential difference of oxygen and carbon monoxide in oxygen. As oxygen concentration was fixed, the sensing potential difference was not affected by the change of background potential.

碩士
中原大學
醫學工程學系
81
Lanthanum Fluoride (LaF3) has been one of the choices as solid electrolyte when the sensors are studied by means of electroche- mistry. It has good ion conductivity at room temperature, stable performace and the insolubility in water. Because of its insolu- bility, one can design the sensors to measure some materials in aqueous solution which makes its biomedical application possible. In our research, the solid electrolyte is produced by pressing the powder of lanthanum fluoride, the working electrode is pro- duced by firing thick film platinum paste, and the reference electrode is produced by sintering the mixture of tin and tin fluoride powder. Two copper wires are fixed by silver glue onto working and reference electrodes respectively. Glucose oxidase ( GOD) is immobilized on the surface of working electrode. Finally ,a thin layer of polyvinyl acetate is coated outside the glucose oxidase to complete the manufacture of the glucose sensor. The response time of the sensor to oxygen of different partial pressure from 0 to 1 atm at 26℃ is 36 minutes. The improvement of the structure of the working electrode (such as the improve- ment of the sintering to make it more porous) may shorten the response time. The response time of individual glucose concen- tration in PBS from 5x10■ to 5x10■ M at 26℃ is reduced to ab- out 5 minutes. It might due to the reaction of hydrogen ions in the aqueous solution. The stability of the sensor under our stu- dies can be obtained at room temperature. The sensitivity to sucrose, galactose, ascorbic acid and hydrogen peroxide also discussed in the report. The ion conductivity of lanthanum flu- oride is under consideration.

Excess fluoride in groundwater used for drinking can pose serious health hazards, especially in poor, rural areas of the developing world lacking water treatment. The World Health Organization recommends a maximum fluoride contaminant level of 1.5 mg/L in drinking water [1]. Over 200 million people in low- and middle-income countries currently drink groundwater over that limit [2]. Current field detection of fluoride typically uses HACH kits, with several groups developing smartphone based alternatives [3]. These methods are based on colorimetry. The HACH kit is limiting because appropriate training is required, results are sensitive to competing ion contamination and chlorine, the glassware must be clean, and repetition is needed to ensure reliability [4]. The use of a smartphone for in-field detection of fluoride is promising and takes a strong step towards quick, easy, reliable, and portable fluoride detection. Our research takes the concept of a portable device one step further by using a fundamentally different, and simpler, mode of detection. We have demonstrated the use of optical fibers as an alternative, non-colourimetric fluoride detection method. The tip of a single mode optical fiber is coated with a thin film of Al and is immersed in an aqueous fluoride solution. The reaction between fluoride and the Al coating changes internal reflection proportional to fluoride concentration which is measured by a photodetector as an output voltage. We made great steps in optimizing the methods, materials, and code required for this sensor. Additionally, we built a device to allow approximate standardization of Al thickness as a function of the distance from the target and time of sputtering. We established the best practical thickness of Al coating, improved repeatability between sputter deposition events, and implemented an optical switch into the experimental set-up.
Graduate
2021-07-28

碩士
國立交通大學
工學院加速器光源科技與應用碩士學位學程
103
Science on research in recent years, the nanowire was extensively studied and discussed, particularly in the application of bio-sensor devices, and is considered one of the most promising components for sensing devices. In our previous research, we successfully demonstrated the SiGe nanowire and by experimental measurement, we confirmed that is presented bio-sensor characteristic. In this thesis, p-type SiGe nanowires were fabricated, which is compatible to VLSI technology. Then we exploited ion-implantation technology to change the concentration of SiGe nanowire by oxidation passivation. Next step, we oxidized SiGe nanowires to precipitate Ge, successfully fabricated non-homogeneous SiGe nonowires. We apply the different doses of fluorine ion-implantation to compare. Finally, we found non-homogeneous SiGe nanowires, which had the best sensitivity. In ours results, SiGe nanowires presented the better application in bio-sensor device.

Structural Health Monitoring (SHM) systems for future structures and vehicles would involve a process of damage identification and prediction of certain quantities of interest that concerns the function and safety. This process provides SHM systems the ability to not only save cost but also enhance the service life, safety and reliability of the structures and vehicles. Integrated SHM system (ISHM) is an advancement of SHM system that has additional capability of predicting the component life/failure. ISHM system development involves detailed understanding of diagnostic waves, hardware components, signal processing paradigms and intelligent use of algorithms. Diagnostic waves like the guided waves are the elastic waves that propagate in a direction defined by the material boundaries. These waves have the capability of traveling large distance probing the entire thickness in plates/shells. Thus, they are widely used by SHM systems in monitoring the plate structures. Piezoelectric transducers are often employed in the interrogation using guided waves. Most SHM systems employing guided waves are designed for specific structures. Current paradigms of SHM systems are unable to enable the transition from simple or ideal structures to realistic and complicated structures. This is due to the challenges at the fundamental level involving transducer, wave propagation and phenomena of guided wave scattering with damages to evaluate the possible solutions through mathematical modeling and signal analysis capability required by ISHM systems. This thesis aims to develop understanding of these problems at a fundamental level. Complex system level understanding is still needed which is left out as open problem. A primary requirement in designing SHM system is the proper understanding of wave characteristics such as number of modes, wavelength and dispersiveness. Although three-dimensional elasticity solution and simplified theories are available to understand them, their applicability in SHM problem requires a much more detailed look. Effort toward this direction has led to the development of simpler models. However, mathematical models are not available for understanding the wave characteristics in complex structures involving stiffeners and adhesive joints. This problem is addressed in this thesis. There is a fair amount of understanding developed regarding transducer characteristics. This is accomplished by analytical and finite element models of transducers in the past. However, simplified transducer model that are computationally fast to suit SHM system requirements needs to be developed. The development of such model is presented in this thesis. Apart from modeling the transducers and wave scattering due to damage, signal correlation and calibration are needed for practical implementation in SHM. Characterization studies reported in published literature are limited to quasi-static and low frequencies applications. However, SHM of aerospace structures employ guided waves typically in the frequency range of 100-500 kHz. Methods to characterize the transducers at this frequency range needs to be developed, which is addressed in this thesis. Another major requirement of SHM system is the design and development of sensor-actuator network and appropriate algorithm. Techniques developed earlier involving transducer arrays in this regard have limitation due to complexity of geometry and signal interpretation that needs to be addressed. The network with suitable algorithm should ideally monitor large area including the critical areas of failure with minimum number of transducers. ISHM systems further require some capability to estimate the useful life of the damaged structure in order to take suitable decisions. Efficient techniques to achieve these are not developed. Overall, there is a need to improve highly interdisciplinary areas involving mathematical modeling, transducer design, fabrication and characterization, damage detection and monitoring strategies. In this thesis, various novel techniques to combine mathematical model with experimental signals to enhance the damage detection capability are presented. In this thesis, developments in the three main aspects of SHM systems are focused upon. They are (1) development of mathematical models of sensors/actuators, wave propagation and scattering due to damage (2) characterization and calibration of transducers and (3) development of technique to monitor wide variety of damages within the scope of ultrasonic guided wave based SHM. The thesis comprises of ten chapters. First chapter is devoted to the background and motivation for the problem addressed in this thesis. In second chapter, brief overview of available mathematical models and conventional damage monitoring strategy is presented. The significant contributions reported in the subsequent chapters in this thesis are outlined below In chapter 3, a reduced-order model of guided wave propagation in thick structures with reduced-order approximation of higher-order elasto-dynamic field is formulated. The surface normal and shear tractions of the thick structure are satisfied in a closed form. The time-frequency Fourier spectral finite element is developed and is validated using detailed and computationally intensive finite element simulations. Natural frequencies obtained from the developed spectral finite element and the detailed finite element simulations are compared. Transient response due to broad frequency band and narrow frequency band excitations given in the form of surface tractions are validated by comparing with the detailed finite element simulations. Using the developed spectral finite element, wave scattering from a free edge and a notch are simulated and validated by comparing with the detailed finite element simulations. In chapter 4, two-dimensional plane wave and flexural wave scattering models for more complicated features such as stiffener with delamination and stiffener with bolt failures in a stiffened panel are derived using ultrasonic ray tracing based approach combined with wave-field representation. Dispersion relations are reformulated for the base plate where it is bolted with the stiffener. Surface conditions due to contact stiffness and contact damping are modeled by introducing springs and dampers. Scattering coefficients for the bonded and bolted stiffeners are derived. The scattering coefficients are evaluated for various different frequencies. Results are compared for different stiffener parameters. In chapter 5, a simplified analytical model of a piezoelectric actuator with uniform electrodes is modeled. The problem is to determine the launched guided wave characteristics in the structure. The analytical model is derived considering two-dimensional elasticity based approach and Airy’s stress function. The actuator model is used to specify the displacement boundary conditions in the detailed finite element model. The radiated wave patterns in a plate due to actuation from transducers of different shapes are obtained and validated with experiments. Phased array actuators are modeled in the detailed finite element model using the displacements estimated from the actuator model. The radiated wave pattern from the detailed finite element simulations are validated with experiments. Chapter 6 is devoted to the design and characterization of transducers for ultrasonic guided wave applications. The characterization techniques involve the estimation of voltage response for the induced strain by the guided wave at various different frequencies. First, a novel removable bonding technique and a calibration technique are demonstrated and related advantages are discussed. Performance of the piezoelectric thin film under quasi-static, dynamic and transient impact loadings are analyzed first. Next, a guided wave technique is developed to characterize piezoelectric thin film sensors and actuators at ultrasonic frequencies. The transducers with inter digital electrodes are characterized for frequency tuning and directional sensitivity. This characterization study enables in the selection of optimal frequency bands for interrogation. Further, the characterization of transducers with thermal degradation is presented. In chapter 7, a novel guided wave technique to calibrate the thin film sensors for ultrasonic applications is presented. Calibration procedure involves the estimation of the piezoelectric coefficient at ultrasonic range of frequencies. Calibration is done by the measurement of voltage generated across thin films when guided waves are induced on them. With the proposed technique, piezoelectric coefficient can be estimated accurately at any frequency of the propagating wave. Similarly, the measurement of piezoelectric coefficient of thin films with inter digital electrodes is presented. The estimation of piezoelectric coefficient at various different directions using laser Doppler vibrometer is presented. Lastly, the degradation of piezoelectric coefficient is studied for increasing thermal fatigue. In chapter 8, toward SHM methodology development, a guided wave based technique to detect and monitor cracks in a structure is presented. To establish the methodology, a detailed study is carried out on the effect of crack and specimen size on the guided wave propagation characteristics. Using the wave characteristics, an analytical way of modeling Lamb wave propagation in the specimen with plastic zone is proposed. The feasibility to determine plastic zone and fatigue crack propagation with integrated piezoelectric transducers is demonstrated experimentally and the results are verified analytically. A method is further established to detect damage at initial stage and crack-tip plastic zone size along with crack length for a given stress amplitude or vice-versa. An approach to estimate fatigue life from the transducer signals is also proposed. In chapter 9, a compact circular array of sensor-actuator network and an algorithm is presented to monitor large plate structures. A method based on the wavelet transforms of transducer signals is established to localize and estimate the severity of damages. Experiments are conducted to demonstrate the capability of the circular array based method in the localization and quantification of various types of damages like debonding of stiffeners, failure of bolted joints, corrosion and hole-enlargement. A damage index is then computed from wavelet time-frequency map that indicates the severity of damage. Chapter 10 ends with the concluding remarks on the work done with simultaneous discussion on the future scope. The work reported in this thesis is interdisciplinary in nature and it aims to combine the modeling and simulation techniques with realistic data in SHM to impart higher confidence levels in the prediction of damages and its prognosis. The work also aims in incorporating various mathematical models of wave propagation and ray tracing based algorithm to optimize the detection scheme employed in SHM. The future direction based on this study could be aimed at developing intelligent SHM systems with high confidence levels so that statistical machine learning would be possible to deal with complex real-world SHM problems.

Structural Health Monitoring (SHM) systems for future structures and vehicles would involve a process of damage identification and prediction of certain quantities of interest that concerns the function and safety. This process provides SHM systems the ability to not only save cost but also enhance the service life, safety and reliability of the structures and vehicles. Integrated SHM system (ISHM) is an advancement of SHM system that has additional capability of predicting the component life/failure. ISHM system development involves detailed understanding of diagnostic waves, hardware components, signal processing paradigms and intelligent use of algorithms. Diagnostic waves like the guided waves are the elastic waves that propagate in a direction defined by the material boundaries. These waves have the capability of traveling large distance probing the entire thickness in plates/shells. Thus, they are widely used by SHM systems in monitoring the plate structures. Piezoelectric transducers are often employed in the interrogation using guided waves. Most SHM systems employing guided waves are designed for specific structures. Current paradigms of SHM systems are unable to enable the transition from simple or ideal structures to realistic and complicated structures. This is due to the challenges at the fundamental level involving transducer, wave propagation and phenomena of guided wave scattering with damages to evaluate the possible solutions through mathematical modeling and signal analysis capability required by ISHM systems. This thesis aims to develop understanding of these problems at a fundamental level. Complex system level understanding is still needed which is left out as open problem. A primary requirement in designing SHM system is the proper understanding of wave characteristics such as number of modes, wavelength and dispersiveness. Although three-dimensional elasticity solution and simplified theories are available to understand them, their applicability in SHM problem requires a much more detailed look. Effort toward this direction has led to the development of simpler models. However, mathematical models are not available for understanding the wave characteristics in complex structures involving stiffeners and adhesive joints. This problem is addressed in this thesis. There is a fair amount of understanding developed regarding transducer characteristics. This is accomplished by analytical and finite element models of transducers in the past. However, simplified transducer model that are computationally fast to suit SHM system requirements needs to be developed. The development of such model is presented in this thesis. Apart from modeling the transducers and wave scattering due to damage, signal correlation and calibration are needed for practical implementation in SHM. Characterization studies reported in published literature are limited to quasi-static and low frequencies applications. However, SHM of aerospace structures employ guided waves typically in the frequency range of 100-500 kHz. Methods to characterize the transducers at this frequency range needs to be developed, which is addressed in this thesis. Another major requirement of SHM system is the design and development of sensor-actuator network and appropriate algorithm. Techniques developed earlier involving transducer arrays in this regard have limitation due to complexity of geometry and signal interpretation that needs to be addressed. The network with suitable algorithm should ideally monitor large area including the critical areas of failure with minimum number of transducers. ISHM systems further require some capability to estimate the useful life of the damaged structure in order to take suitable decisions. Efficient techniques to achieve these are not developed. Overall, there is a need to improve highly interdisciplinary areas involving mathematical modeling, transducer design, fabrication and characterization, damage detection and monitoring strategies. In this thesis, various novel techniques to combine mathematical model with experimental signals to enhance the damage detection capability are presented. In this thesis, developments in the three main aspects of SHM systems are focused upon. They are (1) development of mathematical models of sensors/actuators, wave propagation and scattering due to damage (2) characterization and calibration of transducers and (3) development of technique to monitor wide variety of damages within the scope of ultrasonic guided wave based SHM. The thesis comprises of ten chapters. First chapter is devoted to the background and motivation for the problem addressed in this thesis. In second chapter, brief overview of available mathematical models and conventional damage monitoring strategy is presented. The significant contributions reported in the subsequent chapters in this thesis are outlined below In chapter 3, a reduced-order model of guided wave propagation in thick structures with reduced-order approximation of higher-order elasto-dynamic field is formulated. The surface normal and shear tractions of the thick structure are satisfied in a closed form. The time-frequency Fourier spectral finite element is developed and is validated using detailed and computationally intensive finite element simulations. Natural frequencies obtained from the developed spectral finite element and the detailed finite element simulations are compared. Transient response due to broad frequency band and narrow frequency band excitations given in the form of surface tractions are validated by comparing with the detailed finite element simulations. Using the developed spectral finite element, wave scattering from a free edge and a notch are simulated and validated by comparing with the detailed finite element simulations. In chapter 4, two-dimensional plane wave and flexural wave scattering models for more complicated features such as stiffener with delamination and stiffener with bolt failures in a stiffened panel are derived using ultrasonic ray tracing based approach combined with wave-field representation. Dispersion relations are reformulated for the base plate where it is bolted with the stiffener. Surface conditions due to contact stiffness and contact damping are modeled by introducing springs and dampers. Scattering coefficients for the bonded and bolted stiffeners are derived. The scattering coefficients are evaluated for various different frequencies. Results are compared for different stiffener parameters. In chapter 5, a simplified analytical model of a piezoelectric actuator with uniform electrodes is modeled. The problem is to determine the launched guided wave characteristics in the structure. The analytical model is derived considering two-dimensional elasticity based approach and Airy’s stress function. The actuator model is used to specify the displacement boundary conditions in the detailed finite element model. The radiated wave patterns in a plate due to actuation from transducers of different shapes are obtained and validated with experiments. Phased array actuators are modeled in the detailed finite element model using the displacements estimated from the actuator model. The radiated wave pattern from the detailed finite element simulations are validated with experiments. Chapter 6 is devoted to the design and characterization of transducers for ultrasonic guided wave applications. The characterization techniques involve the estimation of voltage response for the induced strain by the guided wave at various different frequencies. First, a novel removable bonding technique and a calibration technique are demonstrated and related advantages are discussed. Performance of the piezoelectric thin film under quasi-static, dynamic and transient impact loadings are analyzed first. Next, a guided wave technique is developed to characterize piezoelectric thin film sensors and actuators at ultrasonic frequencies. The transducers with inter digital electrodes are characterized for frequency tuning and directional sensitivity. This characterization study enables in the selection of optimal frequency bands for interrogation. Further, the characterization of transducers with thermal degradation is presented. In chapter 7, a novel guided wave technique to calibrate the thin film sensors for ultrasonic applications is presented. Calibration procedure involves the estimation of the piezoelectric coefficient at ultrasonic range of frequencies. Calibration is done by the measurement of voltage generated across thin films when guided waves are induced on them. With the proposed technique, piezoelectric coefficient can be estimated accurately at any frequency of the propagating wave. Similarly, the measurement of piezoelectric coefficient of thin films with inter digital electrodes is presented. The estimation of piezoelectric coefficient at various different directions using laser Doppler vibrometer is presented. Lastly, the degradation of piezoelectric coefficient is studied for increasing thermal fatigue. In chapter 8, toward SHM methodology development, a guided wave based technique to detect and monitor cracks in a structure is presented. To establish the methodology, a detailed study is carried out on the effect of crack and specimen size on the guided wave propagation characteristics. Using the wave characteristics, an analytical way of modeling Lamb wave propagation in the specimen with plastic zone is proposed. The feasibility to determine plastic zone and fatigue crack propagation with integrated piezoelectric transducers is demonstrated experimentally and the results are verified analytically. A method is further established to detect damage at initial stage and crack-tip plastic zone size along with crack length for a given stress amplitude or vice-versa. An approach to estimate fatigue life from the transducer signals is also proposed. In chapter 9, a compact circular array of sensor-actuator network and an algorithm is presented to monitor large plate structures. A method based on the wavelet transforms of transducer signals is established to localize and estimate the severity of damages. Experiments are conducted to demonstrate the capability of the circular array based method in the localization and quantification of various types of damages like debonding of stiffeners, failure of bolted joints, corrosion and hole-enlargement. A damage index is then computed from wavelet time-frequency map that indicates the severity of damage. Chapter 10 ends with the concluding remarks on the work done with simultaneous discussion on the future scope. The work reported in this thesis is interdisciplinary in nature and it aims to combine the modeling and simulation techniques with realistic data in SHM to impart higher confidence levels in the prediction of damages and its prognosis. The work also aims in incorporating various mathematical models of wave propagation and ray tracing based algorithm to optimize the detection scheme employed in SHM. The future direction based on this study could be aimed at developing intelligent SHM systems with high confidence levels so that statistical machine learning would be possible to deal with complex real-world SHM problems.