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1
Bronk, Karen Srour. "Imaging based sensor arrays /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1996.
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Thesis (Ph.D.)--Tufts University, 1996.<br>Adviser: David R. Walt. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
2
Curey, Theodore Edward. "Development of enzyme-based sensor arrays." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3025209.
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Fernández, Romero Luis. "Understanding the role of sensor diversity and redundancy to encode for chemical information in gas sensor arrays." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/395180.
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Electronic noses (e-noses) have been utilized during the past three decades as general purpose instruments for chemical sensing. These instruments are inspired by natural olfactory systems, where fine odour discrimination is performed without the necessity for highly specialized receptors. Instead, odour information is extracted in these systems using arrays of broadly tuned receptors organized in a convergent pathway. Such a sensing architecture allows combining the responses of the array of receptors, giving rise to particular representations of the different odour stimuli. The key advantage provided by this approach is that odour representation is more efficient and robust when the encoding is performed by the population of receptors than by any of its individual elements (hyper-acuity).
A population of receptors obtains its maximum performance in encoding odour stimulus features when it balances the benefits of sensory diversity and redundancy. By sensor diversity we understand the number of different receptor types responsible for enhancing the variability of the array response to a collection of odours. Likewise, by sensor redundancy we refer to the average number of receptor replicates on a population. The role of sensor redundancy accounts for the robustness to receptor damage and noise exhibited by the odour stimuli representation. This variety of odour receptor types along with its outstanding number of receptors is characteristic of natural olfactory systems. Though, traditional electronic noses tend to exhibit a limited number of sensor units with very much correlated responses to odour stimuli. Several strategies to enhance odour representation in gas sensor arrays are based on boosting sensor
diversity and redundancy. However, it has not been until recently that large arrays of cross-selective have become technologically available.
In this dissertation, we have developed one of these new generation arrays to investigate the advantages odour stimuli representation through population coding in artificial olfaction. In particular, we proposed to build a chemical sensing system based on an array of metal oxide (MOX) gas sensors, and endowed with a high a degree of sensor diversity and redundancy. We proposed the use this bio-inspired sensing architecture alongside statistical pattern recognition techniques to cope with some of the unsolved problems in machine olfaction (robustness to sensor damage, feature selection, and calibration transfer). The main contributions of this work were the following: We defined functionally sensor diversity and redundancy. These definitions were based on the clustering of the array features according to their similitude when responding to an odour dataset. We compared the different manner how natural and artificial olfactory systems encode for odour information using simple sensors models. We found that natural olfactory system principally encoded odour information in terms of odour quality, whereas that artificial ones in terms of odour quantity. Also, we studied the effect of sensor noise on odour concentration encoding. We proposed to decrease the contribution of the sensor noise by means of the redundant sensor feature averaging and sensor array optimization. These strategies were effective in case of independent sensor noise, but not for removing common sources of sensor noise. Similarly, we detected the importance of sensor failure dependency on the odour discrimination capabilities of a sensor. We found that this sensor fault distribution across had to be independent of the sensor type to prevent a dramatic worsening on the array’s predictive performance. In addition to this, we proposed an update of a feature selection method including a
dimensionality reduction stage so as to take into account the redundant information provided by the sensor array. Finally, we performed instrument standardization between temperature modulated sensor arrays to correct global shifts of temperature. A method to categorize the quality of the calibration transfer based on the bias-variance trade-off was presented.<br>La nariz electrónica (e-nose) ha sido utilizada durante las últimas tres décadas como instrumento de propósito general para la detección química. Este instrumento está inspirado en los sistemas olfativos naturales, donde la discriminación de olores se realiza eficientemente sin la necesidad de receptores altamente especializados. La ventaja clave proporcionada por esta aproximación es que la representación de los olores es más eficiente y robusta cuando la codificación del olor es llevada a cabo por una población de receptores, pues esta supera la calidad de cualquiera realizada por sus elementos individuales. Una población de receptores obtiene su máximo rendimiento en la codificación de las características de un estímulo odorífero cuando se equilibran los beneficios de la diversidad y redundancia sensoriales. Lamentablemente, las narices electrónicas tradicionales tienden a exhibir un número limitado de sensores con respuestas muy correlacionas ante diferentes conjuntos de estímulos odoríferos. Sin embargo, no ha sido hasta hace relativamente poco que la creación grandes matrices de sensores con selectividades cruzadas ha sido tecnológicamente posibles. El objetivo de esta tesis es el desarrollo de una de estas matrices de nueva generación para investigar las ventajas de la representación de los estímulos odoríferos través de una codificación poblacional soportada por la diversidad y redundancia sensoriales. En particular, hemos construido un sistema de detección química basado en una matriz de sensores de gas de óxido metálico (MOX), y dotada de un alto grado de diversidad y redundancia sensoriales. Hemos utilizado esta arquitectura de detección química bioinspirada junto técnicas de reconocimiento de patrones estadísticas para hacer frente a algunos de los problemas sin resolver en olfacción artificial, a saber, la robustez al fallo de sensores, la
selección de características, y la transferencia de calibración entre diferentes narices electrónicas.
4
Henderson, Christopher M. Jr. "Characterization of high efficiency neutron detector linear arrays." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/2126.
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Weller, Harald. "CMOS monolithic pyroelectric infrared focal plane arrays using PVDF thin films." Thesis, Edinburgh Napier University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323080.
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Wang, Xiaodong. "Integrated thin film metal oxide gas sensor arrays with application to monitoring of organic vapors /." Thesis, Connect to this title online; UW restricted, 1994. http://hdl.handle.net/1773/6095.
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Michael, Karri L. "Development of high-density optical fiber arrays : new designs and applications in microscopy, microfabrication and chemical sensing /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1999.
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Thesis (Ph.D.)--Tufts University, 1999.<br>Adviser: David R. Walt. Submitted to the Dept. of Chemistry. Includes bibliographical references (leaves 233-253). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
8
Badel, Xavier. "Electrochemically etched pore arrays in silicon for X-ray imaging detectors." Doctoral thesis, Stockholm : Department of Microelectronics and Information Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-137.
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Polk, Brian Joseph. "Development of chemically sensitive field-effect transistor arrays and selective materials." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/31008.
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Liao, Bin, and 廖斌. "New direction finding and beamforming algorithms for sensor arrays with uncertainties." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50899806.
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Sensor arrays have been successfully applied to many engineering fields and the theoretical as well as applied aspects of senor array processing have received intensive research interest. Practically, sensor array systems usually suffer from uncertainties such as unknown gains and phases, mutual coupling, and look direction mismatch. In this thesis, problems of direction finding and beamforming in the presence of array uncertainties are addressed, and new algorithms to tackle these problems are developed.
In certain applications, senor arrays are only partly calibrated. Hence, the exact responses of some sensors are unknown, which degrades the performance of traditional direction finding techniques. To tackle this problem, a new method for direction finding with partly calibrated uniform linear arrays (ULAs) is proposed. It generalizes the estimation of signal parameters via rotational invariance techniques (ESPRIT) by modeling the imperfection of the ULA as gain and phase uncertainties. For a fully calibrated array, it reduces to the standard ESPRIT algorithm. In this method, the direction-of-arrivals (DOAs), unknown gains and phases of the uncalibrated sensors can be estimated in closed-form without performing spectral grid search. Moreover, it can be further improved by a refining scheme proposed. Its superiority over existing methods is demonstrated by simulation results.
Apart from unknown gains and phases, the mutual coupling caused by interactions among sensors also seriously deteriorate the performance of array processing techniques. In ULAs, the mutual coupling matrix (MCM) can be approximated as a banded symmetric Toeplitz matrix. Using this specific property, a new parameterization of the steering vector is proposed and the corresponding method for joint estimation of DOAs and MCM is derived. Compared with the conventional subarray-based method, the proposed one makes use of the whole array and achieves better performance especially for weak signals. On the other hand, the specific property is further employed to develop a new approach to calibrate the steering vector. By incorporating the calibrated steering vector with a diagonally loaded robust beamformer, a new adaptive beamformer for ULAs with mutual coupling is obtained. It is found that the resultant steering vector estimate considerably improves the robustness of the beamformer against mutual coupling.
Another common uncertainty in sensor array systems is the look direction mismatch. Though numerous robust beamformers have been developed accordingly, most of them cannot offer sufficient robustness against large look direction errors. To this end, a new robust beamforming method which can flexibly control the magnitude response in the look direction is proposed. By linearizing the nonconvex constraints in the original problem, the resultant problem is convex and can be solved using second-order cone programming (SOCP). Moreover, to further improve the robustness against array covariance uncertainties, this method is extended by optimizing its worst-case performance. Unlike some conventional methods restricted to specific arrays, the proposed method is applicable to arbitrary array geometries. Simulation results show that the proposed method offers comparable performance to the optimal solution for uniform linear arrays, and also achieves good results under different array specifications and geometries.<br>published_or_final_version<br>Electrical and Electronic Engineering<br>Doctoral<br>Doctor of Philosophy
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Smith, Tarren MJ. "Driving techniques for high power PZT transducer arrays." Thesis, Cape Peninsula University of Technology, 2006. http://hdl.handle.net/20.500.11838/1089.
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Thesis Presented for the Degree of
Magister Technologiae
in the Department of Electrical Engineering
Cape Peninsula University of Technology
2006<br>Because of the nature of piezoelectric ceramics and the physical construction pf high
power piezoelectric transducers, such devices are inherently non-linear and become unpredictable
when driven at high power. To drive an ultrasonic transducer or an array
thereof efficiently, specific resonant points are used. These poin~s are characterised by the
devices' mechanical modes of oscillation. At high electrical power levels, the resonance
points of PZT transducers vary. The movement of the resonances points in the frequency
domain, coupled with the transducers high Q, is severe enough to seriously hamper the
devices' efficiency. The problem is specifically apparent when multiple transducer arrays
are driven at power. The electrical fluctuations and interactions of the characteristics of
separate transducers cause arrays to be driven efficiently at a single resonance point.
To efficiently drive an array of PZT transducers it is necessary to employ a .suitable
technique. Although several methods exist in the literature, each is designed for a specific
configuration of transducers and dedicated matching circuitry. The fundamental
flaw in most methods is that they are conceived with the assumption all PZT transducers
are identical and can be driven as such. Inherent nonlinearities caused by poling
and construction methods, result in each transducer to be slightly different causing a
superposition of resonance frequencies for each transducer array.
Existing methods cannot be used to efficiently drive generic transducer arrays and
a novel approach has been adopted to accommodate transducer nonlinearities. This
novel approach can be described as a culmination of two driving techniques and has been
named, Swept Frequency Dwelling (SFD). This thesis examines five different driving
techniques and quantifies their effectiveness by means of experimental evaluation proficiencies.
The driving techniques are grouped into two categories - straight driving
techniques and frequency sweeping techniques - which are compared and evaluated.
In conclusion, a novel method for driving ultrasonic transducer arrays was established
with the aim of eliminating some detrimental effects of other driving techniques, while
exploiting some of their positive attributes and was found to be effective.
12
Solorzano, Soria Ana Maria. "Fire Detectors Based on Chemical Sensor Arrays and Machine Learning Algorithms: Calibration and Test." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/669584.
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In some types of fire, namely, smoldering fires or involving polymers without flame, gases and volatiles appear before smoke is released. Most of the fatalities registered for fires, are caused due to the intoxication of the building occupants over the burns. Nowadays, conventional fire detectors are based on the detection of smoke or airborne particles. In smoldering fires situations, conventional fire detectors triggers the alarm after the release of toxic emissions. The early emission of gas in fires opens the possibility to build fire alarm systems with shorter response times than widespread smoke-based detectors. Actually, the sensitivity of gas sensors to combustion products has been proved for many years. However, already early works remarked the challenge of providing reliable fire detection using chemical sensors. As gas sensors are not specific, they can be calibrated to detect large variety of fire signatures. But, at the same time, they are also potentially sensitive to any activity that releases volatiles when being performed. Cross-sensitivity to water vapor and other chemical compounds make gas-based fire alarm systems prone to false positives. For that reason, the development of reliable and robust fire detectors based on gas sensors relies in pattern recognition and Machine Learning algorithms to discriminate fire from nuisance sensor signatures.
The presented PhD. Thesis explore the role of pattern recognition algorithms for fire detection using detectors based exclusively in chemical sensors. Two prototypes based on different types of gas sensors were designed. The sensor selection was performed to be sensitive to combustion products and to capture other volatiles that may help to discriminate fire and nuisances. Machine Learning algorithms for the prediction of fire were trained using standard fire tests stablished in EU norm 54. Additionally to those test experiments that may induce false alarms were also performed. Two approaches of machine learning algorithms were explore. The first prediction algorithms is based on Partial Least Squares Discriminant Analysis and the second set of algorithms are based on Support Vector Machines.
Additionally, two new methodologies for cost reduction are presented. The first methodology build fire detection algorithms using the combination of Standard fire test and a reduced version of those experiments. The reduced version were performed in a small chamber. The smaller setup allows the performance of experiments in a shorter period of time. In consequence, the number of experiments to test the models increase and also the robustness of the prediction algorithms. The second methodology built general calibration models using replicates of the same sensor array. The use of different units rejects the variance between sensor arrays and allows the construction of general calibration models. The use of a single model to calibrate sensor arrays systems allows the mass production and resulting in the reduction of costs production.<br>Les alarmes convencionals d'incendis es basen en la detecció de fums. Tanmateix, els incendis solen emetre molts volàtils abans d'emetre fum. Altres grups de recerca ja han proposat sistemes detectors d'incendis basats en sensors químics, que poden proporcionar una resposta més ràpida, però segueixen sent propensos a falses alarmes davant d'interferències. Les tècniques de reconeixement de patrons poden ser útils per mitigar aquesta limitació.
En aquesta tesi, es desenvolupen dos detectors d’incendis basats exclusivament en sensors de gas, de diverses tecnologies, que proporcionen una alarma d’incendi basada en algorismes d’aprenentatge automàtic. Els detectors van ser exposats a incendis estandarditzats i a diverses interferències.
La tesi presenta dos enfocaments diferents pel reconeixement de patrons: el primer es basa en una anàlisi discriminant de mínims quadrats parcials, PLS-DA, i el segon es basa en una màquina de vectors de suport, SVM. Els resultats confirmen la capacitat de detectar incendis a una fase inicial del seu desenvolupament i el rebuig de la majoria de les interferències.
A més, es presenten dues metodologies per a la reducció dels costos de calibratge d'agrupacions de sensors de gas per la detecció d'incendis, tenint present que els experiments per avaluar els detectors es fan en una sala d'incendis estàndard i són molt llargs i costosos. La primera metodologia proposada combina dades procedents d'una sala d'incendis estàndard i dades d'experiments fets a petita escala, més ràpids i menys costosos. Els resultats mostren que el rendiment dels models de predicció pot millorar amb la fusió de dades. La segona metodologia de reducció de costos compensa la necessitat de models de calibratge individuals per a cada matriu de sensors (a causa de la variabilitat del sensor) rebutjant la variabilitat del sensor i proporcionant models generals de calibratge.
13
Strasburg, Jana Dee. "Characterization of avalanche photodiode arrays for temporally resolved photon counting /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/9710.
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Wood, Sean James. "Image quality of optical systems when used with focal plane array detectors." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384898.
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Al-Wazzan, Raied Ahmed. "Multi-channel detectors and their application to the spectroscopy of laser produced plasmas." Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318954.
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Handfield, Joseph J. "High resolution source localization in near-field sensor arrays by MVDR technique /." Online version of thesis, 2007. http://hdl.handle.net/1850/5861.
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Bellis, Stephen John. "VLSI implementation of a spectral estimator for use with pulsed ultrasonic blood flow detectors." Thesis, Bangor University, 1996. https://research.bangor.ac.uk/portal/en/theses/vlsi-implementation-of-a-spectral-estimator-for-use-with-pulsed-ultrasonic-blood-flow-detectors(aada8831-f06d-4e23-94d6-341d021a3e62).html.
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The focus of this thesis is on the design and selection of systolic architectures for ASIC implementation of the real-time digital signal processing task of Modi- fied Covariance spectral estimation. When used with pulsed Doppler ultrasound blood flow detectors, the Modified Covariance spectral estimator offers increased sensitivity in the detection of arterial disease over conventional Fourier transform based methods. The systolic model of computation is considered because through pipelining and parallel processing high levels of concurrency can be achieved to attain the nec- essary throughput for real-time operation. Systolic arrays of simple processing units are also well suited for implementation on VLSI. The versatility of the de- sign of systolic arrays using the rigorous data dependence graph methodology is demonstrated throughout the thesis by application to all sections of the spectral estimator design at both word and bit levels. Systolic array design for the model order 4 Modified Covariance spectral estima- tor, known to offer accurate estimation of blood flow mean velocity and d1stur- bance at an acceptable computational burden, is initially discussed. A variety of problem size dependent systolic arrays for real-time implementation of the fixed model order spectral estimator are designed using data dependence graph mapping methods. Optimal designs are chosen by comparison of hardware, com- munication and control costs, as well as efficiency, timing, data flow and accuracy considerations. A cost/benefit analysis, based on results from structural simula- tion of the arrays, allows the most suitable word-lengths to be chosen. Problem size independent systolic arrays are then discussed as means of coping with the huge increases in computational burden for a Modified Covariance spec- tral estimator which is programmable up to high model orders. This type of array can be used to reduce the number of PEs and increase efficiency when compared to the problem size dependent arrays and the research culminates in the proposal of a novel spiral systolic array for Cholesky decomposition.
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Eminoglu, Selim. "Uncooled Infrared Focal Plane Arrays With Integrated Readout Circuitry Using Mems And Standard Cmos Technologies." Phd thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/4/698597/index.pdf.
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This thesis reports the development of low-cost uncooled microbolometer
focal plane arrays (FPAs) together with their integrated readout circuitry for infrared
night vision applications. Infrared microbolometer detectors are based on suspended
and thermally isolated p+-active/n-well diodes fabricated using a standard 0.35 µ<br>m
CMOS process followed by a simple post-CMOS bulk-micromachining process.
The post-CMOS process does not require any critical lithography or complicated
deposition steps<br>and therefore, the FPA cost is reduced considerably. The integrated
readout circuitry is developed specially for the p+-active/n-well diode
microbolometers that provides lower input referred noise voltage than the previously
developed microbolometer readout circuits suitable for the diode type
microbolometers. Two FPAs with 64 ×<br>64 and 128 ×<br>128 array formats have been
implemented together with their low-noise integrated readout circuitry. These FPAs
are first of their kinds where such large format uncooled infrared FPAs are designed
and fabricated using a standard CMOS process.
The fabricated detectors have a temperature coefficient of -2 mV/K, a thermal
conductance value of 1.55 ×<br>10-7 W/K, and a thermal time constant value of 36 ms,
providing a measured DC responsivity (&<br>#8476<br>) of 4970 V/W under continuous bias. The
measured detector noise is 0.69 µ<br>V in 8 kHz bandwidth, resulting a measured
detectivity (D*) of 9.7 ×<br>108 cm&<br>#8730<br>Hz/W. The 64 ×<br>64 FPA chip has 4096 pixels
scanned by an integrated 16-channel parallel readout circuit composed of low-noise
differential transconductance amplifiers, switched capacitor integrators, and
sample-and-hold circuits. It measures 4.1 mm ×<br>5.4 mm, dissipates 25 mW power,
and provides an estimated NETD value of 0.8 K at 30 frames/sec (fps) for an f/1
optics. The measured uncorrected voltage non-uniformity for the 64 ×<br>64 array after
the CMOS fabrication is 0.8 %, which is reduced further down to 0.2 % for the
128 ×<br>128 array using an improved FPA structure that can compensate for the fixed
pattern noise due to the FPA routing. The 128 ×<br>128 FPA chip has 16384
microbolometer pixels scanned by a 32-channel parallel readout circuitry. The
128 ×<br>128 FPA measures 6.6 mm ×<br>7.9 mm, includes a PTAT temperature sensor
and a vacuum sensor, dissipates 25 mW power, and provides an estimated NETD
value of 1 K at 30 fps for an f/1 optics. These NETD values can be decreased below
350 mK with further optimization of the readout circuit and post-CMOS etching
steps. Hence, the proposed method is very cost-effective to fabricate large format
focal plane arrays for very low-cost infrared imaging applications.
19
Moore, Andrew C. "Operating, testing and evaluating hybridized silicon P-I-N arrays /." Link to online version, 2005. https://ritdml.rit.edu/dspace/handle/1850/1174.
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Longhin, Mattia. "Semiconducting bolometric detectors : material optimization and device design for future room temperature THz imaging arrays." Paris 6, 2009. http://www.theses.fr/2009PA066076.
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L’application à grande échelle des technologies liées au rayonnement terahertz (THz) est encore aujourd’hui limitée par leur complexité et les coûts élevés. Dans ce mémoire, nous proposons des détecteurs bolométriques économiques fonctionnant à température ambiante pour application à l’imagerie THz. Dans ce contexte, nous avons tout d’abord étudié le dépôt de films minces de la phase semiconductrice de l’oxyde YBaCuO et optimisé les caractéristiques structurales et électriques des films minces pour les rendre compatibles avec une technologie CMOS. Nous avons ensuite initié et mis en œuvre de nouveaux procédés de technologie pour fabriquer des bolomètres à partir des films minces semiconducteurs. En particulier, nous nous sommes occupés du couplage entre l’antenne THz et l’élément sensible. Finalement, de premiers dispositifs correspondant à différentes configurations possibles du détecteur ont été réalisés et testés.
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Lavigne, John James. "Molecular recognition and molecular sensing : single analyte analysis and multi-component sensor arrays for the simultaneous detection of a plethora of analytes /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Ko, Hyunhyub. "Design of hybrid 2D and 3D nanostructured arrays for electronic and sensing applications." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22606.
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This dissertation presents the design of organic/inorganic hybrid 2D and 3D nanostructured arrays via controlled assembly of nanoscale building blocks. Two representative nanoscale building blocks such as carbon nanotubes (one-dimension) and metal nanoparticles (zero-dimension) are the core materials for the study of solution-based assembly of nanostructured arrays. The electrical, mechanical, and optical properties of the assembled nanostructure arrays have been investigated for future device applications. We successfully demonstrated the prospective use of assembled nanostructure arrays for electronic and sensing applications by designing flexible carbon nanotube nanomembranes as mechanical sensors, highly-oriented carbon nanotubes arrays for thin-film transistors, and gold nanoparticle arrays for SERS chemical sensors.
In first section, we fabricated highly ordered carbon nanotube (CNT) arrays by tilted drop-casting or dip-coating of CNT solution on silicon substrates functionalized with micropatterned self-assembled monolayers. We further exploited the electronic performance of thin-film transistors based on highly-oriented, densely packed CNT micropatterns and showed that the carrier mobility is largely improved compared to randomly oriented CNTs. The prospective use of Raman-active CNTs for potential mechanical sensors has been investigated by studying the mechano-optical properties of flexible carbon nanotube nanomembranes, which contain freely-suspended carbon nanotube array encapsulated into ultrathin (<50 nm) layer-by-layer (LbL) polymer multilayers.
In second section, we fabricated 3D nano-canal arrays of porous alumina membranes decorated with gold nanoparticles for prospective SERS sensors. We showed extraordinary SERS enhancement and suggested that the high performance is associated with the combined effects of Raman-active hot spots of nanoparticle aggregates and the optical waveguide properties of nano-canals. We demonstrated the ability of this SERS substrate for trace level sensing of nitroaromatic explosives by detecting down to 100 zeptogram (~330 molecules) of DNT.
23
Wynn, Carol Jaeger. "Sensor arrays for the measurement of dispersive, flexural waves in structures for signal-to-noise ratio enhancement and angle of arrival determination." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40189.
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Specht, Teressa Rose. "Advancements Toward High Operating Temperature Small Pixel Infrared Focal Plane Arrays: Superlattice Heterostructure Engineering, Passivation, and Open-Circuit Voltage Architecture." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595558942395669.
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Comerma, Montells Albert. "Development of a multichannel integrated circuit for Silicon Photo-Multiplier arrays readout." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/134876.
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The aim of this thesis is to present a solution for the readout of Silicon Photo-Multipliers (SiPMs) arrays improving currently implemented systems. Using as a starting point previous designs with similar objectives a novel current mode input stage has been designed and tested. To start with the design a valid model has been used to generate realistic output from the SiPMs depending on light input. Design has been performed in first place focusing in general applications for medical imaging Positron Emission Tomography (PET) and then using the same topology for a more constrained design in particle detectors (upgrade of Tracker detector at LHCb experiment).
A 16 channel ASIC for PET applications including the novel input stage has demonstrated an excellent timing measurement with good energy resolution measurement and pile-up detection. This document starts with the analysis of the requirements needed to fit such a system, followed by a detailed description of the input stage and analog processing. Signal is divided in the input stage into three different signal paths: timing, energy and pileup. Every channel performs different signal analysis to deliver; a fast time signal output (digital edge), energy output (a linear time over threshold digital output) and a digital bit to signal pile-up. The time information is then ORed between all channels to generate a single timing output. All the pile-up bits are combined in a digital word ready to be readout for the 16 channels. Design has been optimized for reduced power consumption and no components needed to interface inputs and outputs. Digital slow control to tune the circuit behaviour is also included. The prototype measurements have proved to be a valid option for integration in a full system scanner.
An adapted prototype of the input stage using different technology and adapted to the different constraints from a particle detector is also presented. Only simulation results are available since device is still under production. An analysis of the different requirements needed by the SciFi tracker design is summarized. Current specifications are still evolving since final sensor is still not defined, but other requirements and some tunable elements permits to design such prototypes.<br>L’objectiu d’aquesta tesi és presentar una solució per a la lectura de matrius de fotomultiplicadors de silici (SiPM) millorant les característiques de sistemes actuals. Amb aquesta finalitat s’ha dissenyat i provat el circuit d’una nova etapa d’entrada. En primer lloc s’ha dissenyat pensant en aplicacions genèriques i per a imatge mèdica, concretament per a escàners PET (Positron Emission Tomography). Però més endavant s’aplica la mateixa topologia per a una aplicació més concreta i específica com és un detector de partícules (l’actualització del Tracker a l’experiment LHCb). Els SiPM són uns dispositius electrònics relativament nous amb la possibilitat de comptar fotons i millorant algunes característiques dels sensors actuals, com serien la tensió d’operació més baixa, més guany o immunitat a camps magn`etics, mentre manté unes prestacions excel•lents respecte el guany, resolució temporal i rang dinàmic. Aquest tipus de dispositius es troben en constant evolució encara i una gran varietat de fabricants intenten millorar les prestacions, sobretot respecte la eficiència en la detecció de llum, reduir el corrent d’obscuritat, construir matrius més grans i augmentar l’espectre al qual són sensibles.
En aquest document es presenta el disseny d’un circuit integrat específic amb les següents característiques: gran rang dinàmic, alta velocitat, multicanal, amb entrada en corrent i baixa impedància d’entrada, baix consum, control de la tensió de polarització del SiPM i amb les sortides de; temps, càrrega i apilament.
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Knight, Andrew Keith. "Advanced Detection Technology for Ion Mobility and Mass Spectrometry." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/193700.
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The development of new technologies and the advancement of existing technical expertise can allow for dramatic improvements to be realized in analytical instrumentation. The development of an integrating solid-state ion detector, designed to have a high sensitivity as well as maintaining a high-level of stability, is described and evaluated. Several versions of the charge-transimpedance amplifier (CTIA) technology were constructed with different operating features. The CTIA-1 is a 32-pixel array detector designed for mass spectrometry. It has the capability to simultaneously detect multiple ion channels with a detection limit less than 100 ions. The CTIA-2 detector features an independent selectable gain for each detection channel. The CTIA-2 is a 4-channel device designed for ion mobility. Further design features were built into the CTIA-5 such as differential noise reduction capabilities.The CTIA-1 technology was evaluated for use in isotope ratio mass spectrometry on a custom-built Mattauch-Herzog mass spectrometer. An evaluation was conducted in terms of the detector sensitivity, stability, accuracy, precision, resolution, and mass bias. The CTIA-2 was tested on a sector mass spectrometer for its response to low ion currents of both positive and negative ions. The detector stability, its accuracy, and its precision were studied.The technique of ion mobility spectrometry is rapidly growing, as it is the main technology used for the detection of explosives at security checkpoints. The need to improve the sensitivity of existing ion mobility instruments has led to the exploration of using the CTIA detector in ion mobility instruments. Improvements in sensitivity of two to three orders of magnitude have been demonstrated using the described CTIA detectors. Additional applications that use ion mobility instruments for the detection of analytes have been presented, the chemical mapping of a halogen-contaminated sand bed, the detection of pesticides, as well as the detection of TNT in drinking water.Results indicate that the CTIA detector technology is well suited for use in both mass spectrometry and ion mobility. The sensitive and stable multi-array CTIA detectors perform well in isotope ratio mass spectrometry. Ion mobility instruments of all types can benefit from the added sensitivity supplied by this technology.
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More, Daesha. "Microhotplate Sensor Array Fabrication." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/MoreD2007.pdf.
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Sisk, Brian Christopher Blake Geoffrey A. "Computational optimization of chemical vapor detector arrays /." Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-02152005-125249.
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Beebe, Kenneth Russell. "Multivariate calibration and sensor array design /." Thesis, Connect to this title online; UW restricted, 1987. http://hdl.handle.net/1773/8641.
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Sohn, Young-Soo. "MEMS based microfluidic structure for biological and chemical sensor array /." Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3008446.
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McCaughrean, Mark J. "The astronomical application of infrared array detectors." Thesis, University of Edinburgh, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380441.
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Riffe, Matthew Joseph. "Wireless MRI Detector Arrays: Technology & Clinical Applications." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1377183452.
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Milner, Thomas Edward. "The optical design of far-infrared detector arrays." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185663.
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The imaging properties of far infrared detector arrays are analyzed. An arbitrary optical system imaging partially coherent light is reviewed. The imaging and detection process is correlated to the coherence properties of the imaged light. A selection set of optical flux concentrator arrays is set forth with reference to a literature review. A selection procedure for the concentrators is outlined which includes a derived performance function. Transverse and longitudinal detector geometries are frequently considered in far infrared imaging problems. A ray model is constructed to describe the optical-transverse detector system. The absorbed photon density in a transverse detector is computed with a Monte Carlo simulation. The subsequent transport of the photogenerated holes is evaluated by solving the steady state diffusion equation. With the evaluation of the steady state current density, transfer functions, point spread functions and diffusive cross talk are determined. With a Boltzmann transport equation approach, the response of a longitudinal detector array is analyzed. Signal equations are derived which relate the signal current density to the absorbed photon distribution and other relevant parameters. The various parameters derive from scattering and recombination of the photogenerated charges. Each parameter is qualitatively discussed, mathematically analyzed and algebraicly modeled. The absorbed photon distribution is computed with the aid of an optical multilayer model. The absorptive efficiency and the spatial distribution of the absorbed photons is computed for various layers of the longitudinal detector. The imaging response of the detector array is evaluated from the derived signal equations. An analytical expression is derived for the transfer function of an arbitrary optical-longitudinal detector array system. The derived transfer function includes the effects of diffusion and recombination of the photogenerated charges. Alternate measures of the detector's imaging response are derived; the transfer function, the point response function, the diffusive cross talk and the responsivity are computed as a function of various detector operating and design parameters. Conclusions which relate the detector's imaging performance to several operating and design parameters are made.
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Sundar, Meghana. "Sensor array optimization application of cluster analysis and genetic algorithms for sensor selection /." Diss., Online access via UMI:, 2007.
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Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2007.<br>Includes bibliographical references.
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Canals, Gil Joan. "A portable device for time-resolved fluorescence based on an array of CMOS SPADs with integrated microfluidics." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/669582.
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Traditionally, molecular analysis is performed in laboratories equipped with desktop instruments operated by specialized technicians. This paradigm has been changing in recent decades, as biosensor technology has become as accurate as desktop instruments, providing results in much shorter periods and miniaturizing the instrumentation, moving the diagnostic tests gradually out of the central laboratory. However, despite the inherent advantages of time-resolved fluorescence spectroscopy applied to molecular diagnosis, it is only in the last decade that POC (Point Of Care) devices have begun to be developed based on the detection of fluorescence, due to the challenge of developing high-performance, portable and low-cost spectroscopic sensors. This thesis presents the development of a compact, robust and low-cost system for molecular diagnosis based on time-resolved fluorescence spectroscopy, which serves as a general-purpose platform for the optical detection of a variety of biomarkers, bridging the gap between the laboratory and the POC of the fluorescence lifetime based bioassays. In particular, two systems with different levels of integration have been developed that combine a one-dimensional array of SPAD (Single-Photon Avalanch Diode) pixels capable of detecting a single photon, with an interchangeable microfluidic cartridge used to insert the sample and a laser diode Pulsed low-cost UV as a source of excitation. The contact-oriented design of the binomial formed by the sensor and the microfluidic, together with the timed operation of the sensors, makes it possible to dispense with the use of lenses and filters. In turn, custom packaging of the sensor chip allows the microfluidic cartridge to be positioned directly on the sensor array without any alignment procedure. Both systems have been validated, determining the decomposition time of quantum dots in 20 nl of solution for different concentrations, emulating a molecular test in a POC device.<br>Tradicionalment, l'anàlisi molecular es realitza en laboratoris equipats amb instruments de sobretaula operats per tècnics especialitzats. Aquest paradigma ha anat canviant en les últimes dècades, a mesura que la tecnologia de biosensor s'ha tornat tan precisa com els instruments de sobretaula, proporcionant resultats en períodes molt més curts de temps i miniaturitzant la instrumentació, permetent així, traslladar gradualment les proves de diagnòstic fora de laboratori central. No obstant això i malgrat els avantatges inherents de l'espectroscòpia de fluorescència resolta en el temps aplicada a la diagnosi molecular, no ha estat fins a l'última dècada que s'han començat a desenvolupar dispositius POC (Point Of Care) basats en la detecció de la fluorescència, degut al desafiament que suposa el desenvolupament de sensors espectroscòpics d'alt rendiment, portàtils i de baix cost. Aquesta tesi presenta el desenvolupament d'un sistema compacte, robust i de baix cost per al diagnòstic molecular basat en l'espectroscòpia de fluorescència resolta en el temps, que serveixi com a plataforma d'ús general per a la detecció òptica d'una varietat de biomarcadors, tancant la bretxa entre el laboratori i el POC dels bioassaigs basats en l'anàlisi de la pèrdua de la fluorescència. En particular, s'han desenvolupat dos sistemes amb diferents nivells d'integració que combinen una matriu unidimensional de píxels SPAD (Single-Photon Avalanch Diode) capaços de detectar un sol fotó, amb un cartutx microfluídic intercanviable emprat per inserir la mostra, així com un díode làser UV premut de baix cost com a font d'excitació. El disseny orientat a la detecció per contacte de l'binomi format pel sensor i la microfluídica, juntament amb l'operació temporitzada dels sensors, permet prescindir de l'ús de lents i filtres. Al seu torn, l'empaquetat a mida de l'xip sensor permet posicionar el cartutx microfluídic directament sobre la matriu de sensors sense cap procediment d'alineament. Tots dos sistemes han estat validats determinant el temps de descomposició de "quantum dots" en 20 nl de solució per a diferents concentracions, emulant així un assaig molecular en un dispositiu POC.
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Zarzana, Christopher Andrew. "The Use of Capacitive Transimpedance Amplifier Array Detectors for Mass Spectrometry." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202954.
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Mass spectrometry is a powerful tool in the field of analytical chemistry. Though there have been numerous advances in mass analyzer technology over the decades, there has been comparatively little advancement in mass spectrometer detector technology. The development of the scientific charged-coupled device over 30 years ago brought the advantages of simultaneous detection over single channel detection to optical spectroscopy, including higher signal-to-noise ratios for a fixed analysis time, shorter analysis time to obtain a given signal-to-noise ratio, and greater sample throughput. While the use of array detectors to achieve simultaneous detection is commonplace in optical spectroscopy, ion detectors for mass spectrometry have lagged behind.Over the last decade, a new type of ion detector, the capacitive transimpedance amplifier (CTIA) array detector, has been developed that has a number of properties that make it an excellent tool for simultaneous detection using dispersive mass spectrometers. The CTIA array detector has high sensitivity as well as high gain stability, allowing it to excel in applications that require high precision measurements of ion signals, such as isotope ratio mass spectrometry.Capacitive transimpedance amplifier array detectors have previously been used to demonstrate the power of simultaneous detection on Mattauch-Herzog double focusing mass spectrometers, but the non-linear mass dispersion of these instruments means that the resolution is not constant across the array. A different type of dispersive instrument, the linear cycloid, has a linear mass dispersion, making it a good candidate for an array detector.The first detailed characterization of gain, read noise and dark-current noise, as well as of operating behavior over a range of temperatures, of the DM0025, a 1696 pixel CTIA array detector was performed.In addition, the first-ever combination of a CTIA array detector with a linear cycloid mass spectrometer was developed. This combined instrument demonstrated simultaneous detection of multiple masses, as well as a linear mass range. The results from the detailed characterization of the detector were used in conjunction with measurements of the performance of the combined instrument to suggest improvements for the next generation of linear cycloid instruments with CTIA array detectors.
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Yildirim, Omer Ozgur. "High Performance Readout Electronics For Uncooled Infrared Detector Arrays." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12607504/index.pdf.
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This thesis reports the development of high performance readout electronics for resistive microbolometer detector arrays that are used for uncooled infrared imaging. Three different readout chips are designed and fabricated by using a standard 0.6 µ<br>m CMOS process. Fabricated chips include a conventional capacitive transimpedance amplifier (CTIA) type readout circuit, a novel readout circuit with dynamic resistance nonuniformity compensation capability, and a new improved version of the CTIA circuit.
The fabricated CTIA type readout circuit uses two digital-to-analog converters (DACs) with multiple analog buses which compensate the resistance nonuniformity by adjusting the bias currents of detector and reference resistors. Compensated detector current is integrated by a switched capacitor integrator with offset cancellation capability followed by a sample-and-hold circuit. The measured detector referred current noise is 47.2 pA in an electrical bandwidth of 2.6 KHz, corresponding to an expected SNR of 530.
The dynamic nonuniformity compensation circuit uses a feedback structure that dynamically changes the bias currents of the reference and detector resistors. A special feature of the circuit is that it provides continuous compensation for the detector and reference resistances due to temperature changes over time. Test results of the fabricated circuit show that the circuit reduces the offset current due to resistance nonuniformity 42.5 times. However, the calculated detector referred current noise is 360 pA, which limits the circuit SNR to 70.
The improved CTIA type readout circuit introduces a new detector biasing method by using an additional auxiliary biasing transistor for better current controllability. The improved readout circuit alleviates the need for high resolution compensation DACs, which drastically decreases the circuit area. The circuit occupies an area of one seventh of the first design. According to test results, the current compensation ratio is 170, and the detector referred current noise is 48.6 pA in a 2.6 KHz bandwidth.
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Toprak, Alperen. "Cmos Readout Electronics For Microbolometer Type Infrared Detector Arrays." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610390/index.pdf.
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This thesis presents the development of CMOS readout electronics for microbolometer type infrared detector arrays. A low power output buffering architecture and a new bias correction digital-to-analog converter (DAC) structure for resistive microbolometer readouts is developed<br>and a 384x288 resistive microbolometer FPA readout for 35 µ<br>m pixel pitch is designed and fabricated in a standard 0.6 µ<br>m CMOS process. A 4-layer PCB is also prepared in order to form an imaging system together with the FPA after detector fabrication.
The low power output buffering architecture employs a new buffering scheme that reduces the capacitive load and hence, the power dissipation of the readout channels. Furthermore, a special type operational amplifier with digitally controllable output current capability is designed in order to use the power more efficiently. With the combination of these two methods, the power dissipation of the output buffering structure of a 384x288 microbolometer FPA with 35 µ<br>m pixel pitch operating at 50 fps with two output channels can be decreased to 8.96% of its initial value.
The new bias correction DAC structure is designed to overcome the power dissipation and noise problems of the previous designs at METU. The structure is composed of two resistive ladder DAC stages, which are capable of providing multiple outputs. This feature of the resistive ladders reduces the overall area and power dissipation of the structure and enables the implementation of a dedicated DAC for each readout channel. As a result, the need for the sampling operation required in the previous designs is eliminated. Elimination of sampling prevents the concentration of the noise into the baseband, and therefore, allows most of the noise to be filtered out by integration.
A 384x288 resistive microbolometer FPA readout with 35 &<br>#956<br>m pixel pitch is designed and fabricated in a standard 0.6 &<br>#956<br>m CMOS process. The fabricated chip occupies an area of 17.84 mm x 16.23 mm, and needs 32 pads for normal operation. The readout employs the low power output buffering architecture and the new bias correction DAC structure<br>therefore, it has significantly low power dissipation when compared to the previous designs at METU. A 4-layer imaging PCB is also designed for the FPA, and initial tests are performed with the same PCB. Results of the performed tests verify the proper operation of the readout. The rms output noise of the imaging system and the power dissipation of the readout when operating at a speed of 50 fps is measured as 1.76 mV and 236.9 mW, respectively.
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Wang, Jingyu. "Optical coherence tomography methods using 2-D detector arrays." Thesis, University of Kent, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.650808.
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Optical coherence tomography (OCT) is a non-invasive, non-contact optical technique that allows cross-section imaging of biological tissues with high spatial resolution, high sensitivity and high dynamic range. Standard OCT uses a focused beam to illuminate a point on the target and detects the signal using a single photodetector. To acquire transverse information, transversal scanning of the illumination point is required. Alternatively, multiple OCT channels can be operated in parallel simultaneously; parallel OCT signals are recorded by a two-dimensional (2D) detector array. This approach is known as Parallel-detection OCT. In this thesis, methods, experiments and results using three parallel OCT techniques, including full -field (time-domain) OCT (FF-OCT), full-field swept-source OCT (FF-SS-OCT) and line-field Fourier-domain OCT (LF-FD-OCT), are presented. Several 2D digital cameras of different formats have been used and evaluated in the experiments of different methods. With the LF-FD-OCT method, photography equipment, such as flashtubes and commercial DSLR cameras have been equipped and tested for OCT imaging. The techniques used in FF-OCT and FF-SS-OCT are employed in a novel wavefront sensing technique, which combines OCT methods with a Shack-Hartmann wavefront sensor (SH-WFS). This combination technique is demonstrated capable of measuring depth-resolved wavefront aberrations, which has the potential to extend the applications of SH-WFS in wavefront-guided biomedical imaging techniques.
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Luthman, Anna Siri Naemi. "Spectrally resolved detector arrays for multiplexed biomedical fluorescence imaging." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274904.
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The ability to resolve multiple fluorescent emissions from different biological targets in video rate applications, such as endoscopy and intraoperative imaging, has traditionally been limited by the use of filter-based imaging systems. Hyper and multispectral imaging facilitate the detection of both spatial and spectral information in a single data acquisition, however, instrumentation for spatiospectral data acquisition is typically complex, bulky and expensive. This thesis seeks to overcome these limitations by using recently commercialised compact and robust hyper/multispectral cameras based on spectrally resolved detector arrays. Following sensor calibrations, which devoted particular attention to the angular sensitivity of the sensors, we integrated spectrally resolved detector arrays into a wide-field and an endoscopic imaging platform. This allowed multiplexed reflectance and fluorescence imaging with spectrally resolved detector array technology in vitro, in tissue mimicking phantoms, in an ex vivo oesophageal model and in vivo in a mouse model. A hyperspectral linescan sensor was first integrated in a wide-field near-infrared reflectance based imaging set-up to assess the suitability of spectrally resolved detector arrays for in vivo imaging of exogenous fluorescent contrast agents. Using this fluorescence hyperspectral imaging system, we could accurately resolve the presence and concentration of seven fluorescent dyes in solution. We also demonstrated high spectral unmixing precision, signal linearity with dye concentration, at depth in tissue mimicking phantoms, and delineation of four fluorescent dyes in vivo. After the successful demonstration of multiplexed fluorescence imaging in a wide-field set-up, we proceeded to combine near-infrared multiplexed fluorescence imaging with visible light spectral reflectance imaging in an endoscopic set-up. A multispectral endoscopic imaging system, capable of simultaneous reflectance and fluorescence imaging, was developed around two snapshot spectrally resolved detector arrays. In the process of system integration and characterisation, methods to characterise and predict the imaging performance of spectral endoscopes were developed. With the endoscope we demonstrated simultaneous imaging and spectral unmixing of chemically oxy/deoxygenated blood and three fluorescent dyes in a tissue mimicking phantom, and of two fluorescent dyes in an ex vivo oesophageal porcine model. With further developments, this technology has the potential to become applicable in medical imaging for detection of diseases such as gastrointestinal cancers.
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Lu, Qi Charles. "Active tamper-detector hardware mechanism and FPGA implementation /." Diss., Online access via UMI:, 2006.
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Choudhury, Arnab. "A piezoresistive microcantilever array for chemical sensing applications." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/26623.
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Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2008.<br>Committee Chair: Hesketh, Peter; Committee Member: Bottomley, Lawrence; Committee Member: Degertekin,Levent; Committee Member: Hu, Zhiyu; Committee Member: Janata, Jiri; Committee Member: Zhang, Zhoumin. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Nguyen, Thuyen Huu Manh. "A photovoltaic detector technology based on plasma-induced p-to-n type conversion of long wavelength infrared HgCdTe." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0098.
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[Truncated abstract] HgCdTe is the leading semiconductor material for the fabrication of high performance infrared photon detectors, in particular, for detection of radiation beyond the near infrared. State-of-the-art infrared detection and imaging systems are currently based around high density focal plane arrays consisting of HgCdTe photodiodes as detector elements. Despite the high performance of HgCdTe infrared detectors, and the many benefits they can offer to industry and society, their utilisation remains limited due to the high cost of production. The chemical composition and narrow bandgap of the HgCdTe material used for infrared detection means that the material is inherently very susceptible to defect formation caused by the processing procedures required for device fabrication. Consequently, fabrication of HgCdTe photodiode arrays have traditionally been characterised by low yields and high costs for arrays that meet required operability specifications. In this thesis a new photodiode fabrication technology with the potential to improve device yields over traditional fabrication technologies is presented. This new fabrication technology is distinguished from others by the use of plasma-induced p-to-n type conversion of HgCdTe for junction formation. This allows great simplification of the fabrication process and avoids high temperature processing during and after junction formation, and keeps the junction protected from the atmosphere at all stages of fabrication. The development of the photodiode fabrication technology using plasma-induced junction formation has involved characterising the electrical transport properties of the type-converted layers, fabrication and characterisation of photodiodes, and photodiode dark current modelling
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Kucukkomurler, Alper. "Camera Electronics And Image Enhancement Software For Infrared Detector Arrays." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614106/index.pdf.
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This thesis aims to design and develop camera electronics and image enhancement software for infrared detector arrays. It first discusses the camera electronics suitable for infrared detector arrays, then it concentrates on image enhancement software that are implemented including defective pixel correction, contrast enhancement, noise reduction and pseudo coloring. After that, testing and results of the implemented algorithms were presented.
Camera electronics and circuit operation frequency are selected considering the available standard programmable devices and the output rate of the detector readout circuitry. The target device for implementation of algorithms was Xilinx Spartan &ndash<br>3 XC3S1500 which is used in the camera tests at METU-MEMS Research and Applications Center. Considering the real time operation, the target clocking frequency for operation of the circuitry was selected as 2MHz. Image enhancement algorithms primarily aim to be implemented for 320 x 240 resolution detectors, however with parametric implementation, they aim to support other resolutions, including 160 x 120 and 640 x 512. In addition, all implementations aim to be modular and reusable.
Various different approaches are used for image enhancement software: (i) defective pixel correction is achieved by using a selective median filtering approach, (ii) contrast enhancement is achieved by employing contrast stretching and histogram based methods, and (iii) noise reduction is achieved by implementing a spatial filter. In addition to these, four types of pseudo coloring methods were applied and tested.
Test results show that defective pixel correction algorithm operates at 20.0 MHz, with 0.0 x 10-3 RMS error from its MATLAB prototype, and contrast enhancement algorithms are able to operate at 3.3 MHz, with an average of 545.0 x 10-3 RMS error. Spatial filtering for noise reduction operates at 20.0 MHz, with a 2.6 x 10-3 RMS. Pseudo-coloring operates at 125.0 MHz, with a 0.0 x 10-3 RMS deviation from its MATLAB prototype,
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Guo, Bin. "A bio-inspired electronic nose micro-system based on integrated gas sensor array and log-spike processing /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?ECED%202008%20GUO.
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Gresham, Christopher Allen 1965. "Near-infrared spectroscopy utilizing array detector technology." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282690.
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A near-infrared spectrometer incorporating solid-state design applicable for industrial quantitative/qualitative process monitoring analysis is presented. The solid-state near-infrared spectrometer provides inherent wavelength stability necessary for long term calibration accuracy. The spectrometer consists of a 24 volt, 10 watt quartz-halogen-tungsten regulated source with optical feedback. Wavelength dispersion was accomplished using a 50 μm entrance slit, f/4, 0.25 meter spectrograph equipped with astigmatism correcting toroidal mirrors and a 300 gr/mm plane reflectance ruled grating blazed for 2000 nm peak efficiency. A 1024 element backside- illuminated Schottky-barrier PtSi photodiode array detector with wavelength response from 900-5000 nm and peak quantum efficiency of 8% at 1100 nm was operated using cryogenic cooling to reduce dark response. A readout rate of 31.25 kHz produced 41 msec integration time per array read. The readout was digitized to 16 bit resolution for subsequent data storage. This system demonstrated 1.5 nm spectral bandpass, 3 orders linear dynamic range and typical baseline rms noise level of 10⁻⁴ a.u. Using this system, quantitative/qualitative chemical analyses were performed focusing on industrial analytical chemical applications. Simultaneous quantitative multcomponent xylene isomer mixtures analysis was achieved using the solid-state near-infrared spectrometer coupled with partial least squares regression multivariate data treatment. The results demonstrate an absolute accuracy of ± 0.05, ±0.12 and ±0.09% w/v for o-, m- and p-xylene isomers respectively. In a separate chemical study, qualitative classification analysis of specially denatured alcohol mixtures was successfully performed on 53 validation samples using 35 reference samples belonging to 12 classes. The validation set included mixture sample types used for model calibration as well as others composed of compounds not used for model calibration. The multivariate cluster classification method using principal components was employed to correctly classify 100% of the validations samples analyzed. The solid-state near-infrared spectrometer was also applied for direct reaction monitoring of the O-H overtone absorption band at 1411 nm for the reaction between triisopropyl-chlorosilane and methanol. The results illustrated the utility of near-infrared functional group monitoring of reactions at relatively high concentrations for information elucidation concerning reaction initiation and completion.
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Silva, Tiago Polizer da. "Anemômetro ultrassônico unidimensional baseado em correlação cruzada." Universidade Tecnológica Federal do Paraná, 2016. http://repositorio.utfpr.edu.br/jspui/handle/1/1929.
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Este trabalho descreve o desenvolvimento de um medidor de velocidade de vento aplicando técnicas da teoria de erros, como a correlação cruzada, bem como sensores de ultrassom. Ele pode ser utilizado em encanamentos, onde se busca obter a velocidade de fluídos, em estações climáticas, em aeroportos, no momento de se aplicar pesticidas assim como em fazendas eólicas, onde o conhecimento da velocidade do vento é necessário, dentre outras aplicações. O sistema desenvolvido é composto pela placa de desenvolvimento de0-nano, uma placa de circuito impresso (PCB) para aquisição de sinais e dois pares de sensores de ultrassom. A PCB também possui circuitos para excitação dos sensores de ultrassom bem como comunicação com o PC para armazenamento dos sinais amostrados. A teoria de erros foi discutida e os resultados do protótipo foram analisados utilizando métodos probabilísticos necessários para verificar a incerteza. Dentro da FPGA da placa de0-nano foi desenvolvido um sistema baseado no processador NIOS, o qual foi construído através da ferramenta QSYS. Além disso, blocos em VHDL foram desenvolvidos para interfaceamento do sistema com o PC. Um pequeno túnel de vento foi construído e um anemômetro de mão foi adquirido para validar o protótipo. Simulações foram realizadas no Microsoft Excel 2007 para comparar a correlação cruzada dada pelo protótipo e a teoria. É comum que DSPs e Microprocessadores estejam dentro de medidores de velocidade do vento, no entanto um sistema desenvolvido com FPGA aumenta a velocidade de processamento devido ao paralelismo. Blocos descritos em VHDL podem ser facilmente replicados dentro da FPGA e existe uma grande coleção de bibliotecas, literatura extensiva e exemplos de código para o NIOS. Com isso há um menor tempo de desenvolvimento de um protótipo/sistema e há facilidade de desenvolver um System on Chip (SoC) de sistemas baseados em FPGA, reduzindo os custos de um futuro produto comercial.<br>This work describes the development of one axis wind speed measurement equipment applying error theory techniques, as the cross correlation, and ultrasound sensors. It can be used in tubes, where fluid speed knowledge is needed, climate stations, airports, in the moment of applying pesticides and in wind farms, where wind speed knowledge is necessary. The built prototype is a connected set of a de0-nano development board, a signal acquisition printed circuit board and two pairs of ultrasound sensors. The PCB also has circuits for ultrasound sensors exciting and PC communications to store the sampled signals. The error theory was discussed and the prototype's results were developed using probabilistic methods needed to verify the uncertainty. Inside de0-nano board FPGA chip, a system based in NIOS processor was developed and built through QSYS tool. There are some blocks described in VHDL for PCB interfacing. A small wind tunnel was built and a hand anemometer was acquired to validate the proposed system. Simulations were done in Microsoft Excel 2007 to compare the cross correlation given by the prototype and the theory. It is common DSPs and microprocessors inside this type of equipments to measure wind speed, but a system developed with a FPGA increases the processing speed due to parallelism. Blocks described in VHDL can be easily replicated inside the FPGA and there is a large collection of libraries, extensive literature and code examples for NIOS. Thereby there are small system/prototype developing times and there is an easy development of a System on Chip (SOC) of FPGA based systems, reducing the costs for a future commercial product.
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Himsworth, John M. "Linear array CMOS detectors for laser Doppler blood flow imaging." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/12392/.
Full textAbstract:
Laser Doppler blood flow imaging is well established as a tool for clinical research. The technique has considerable potential as an aid to diagnosis and as a treatment aid in a number of situations. However, to make widespread clinical use of a blood flow imager feasible a number of refinements are required to make the device easy to use, accurate and safe. Existing LDBF systems consist of 2D imaging systems, and single point scanning systems. 2D imaging systems can offer fast image acquisition time, and hence high frame rate. However, these require high laser power to illuminate the entire target area with sufficient power. Single point scanning systems allow lower laser power to be used, but building up an image of flow in skin requires mechanical scanning of the laser, which results in a high image acquisition time, making the system awkward to use. A new approach developed here involves scanning a line along a target, and imaging the line with a 1D sensor array. This means that only one axis of mechanical scanning is required, reducing the scanning speed, and the laser power is vastly reduced from that required for a 2D system. This approach lends itself well to the use of integrated CMOS detectors, as the smaller pixel number means that a linear sensor array can be implemented on an IC which has integrated processing while keeping overall IC size, and hence cost, lower than equivalent 2D imaging systems. A number of front-end and processing circuits are investigated in terms of their suitability for this application. This is done by simulating a range of possible designs, including several logarithmic pixels, active pixel sensors and opamp-based linear front-ends. Where possible previously fabricated ICs using similar sensors were tested in a laser Doppler flowmetry system to verify simulation results. A first prototype IC (known as BVIPS1) implements a 64x1 array of buffered logarithmic pixels, chosen for their combination of sufficient gain and bandwidth and compact size. The IC makes use of the space available to include two front-end circuits per pixel, allowing other circuits to be prototyped. This allows a linear front-end based on opamps to be tested. It is found that both designs can detect changes in blood flow despite significant discrepancies between simulated and measured IC performance. However, the signal-noise ratio for flux readings is high, and the logarithmic pixel array suffers from high fixed pattern noise, and noise and distortion that makes vein location impossible. A second prototype IC (BVIPS2) consists of dual 64x1 arrays, and integrated processing. The sensor arrays are a logarithmic array, which addresses the problems of the first IC and uses alternative, individually selectable front-ends for each pixel to reduce fixed-pattern noise, and an array of opamp-based linear detectors. Simulation and initial testing is performed to show that this design operates as intended, and partially overcomes the problems found on the previous IC - the IC shows reduced fixed pattern noise and better spatial detection of blood flow changes, although there is still significant noise.
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Pomeroy, Robert S. "Spark emission spectroscopy utilizing CID array detectors and related studies." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185942.
Full textAbstract:
In the analysis of solid samples, there are two distinct advantages to performing direct analysis on the solid: (1) minimal sample preparation and (2) avoids potential sample contamination from the reagents used in the dissolution process. The two most common optical techniques for direct solids analysis are arc and spark emission spectroscopy. The most important drawback associated with arc and spark spectroscopy is in the acquistion and interpretation of the spectrum. The development of a custom echelle spectrometer with Charge Injection Device (CID) array detection carried out in these laboratories should be particularly well suited for arc and spark emission spectroscopy. CIDs exhibit many of the best characteristics of photographic film and PMT detection while providing the added advantage of nondestructive readout and Random Access Integration (RAI). This thesis describes the work coupling a spark source to a CID/echelle spectrometer. When properly shielded, the sensitive electronics of the CID function normally in the presence of the spark discharge. The potential for this system to be able to handle the wide variety of spectroscopic situations resulting from the complex spectra typically obtained with this type of excitation is attributed to the flexibility of the instrument which allows the use of alternate line for analysis and internal standard calibration. Additionally, the use of multiple lines has been applied to comparative analysis, monitoring the background for changes in excitation, and determination of the optimum lines to be used for quantification. Effective utilization of the large database of spectral information has lead to the development of sophisticated expert systems such as automated qualitative and semiquantitative analysis routines. Preliminary work with an astigmatism free imaging spectrograph and a Charge Coupled Device (CCD) array detector has shown the ease with which spatial and spectral maps of emission source can be generated. Observation of the spark discharge process in a hope of gaining a clearer picture of the mechanisms of sample excitation seems to be the most rational approach to ultimately obtaining control over the spark process and alleviating the problems associated with sparks excitation.
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Stitzel, Shannon E. "Microsphere array-based artificial nose : a continuing study toward multiple applications /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2003.
Find full textAbstract:
Thesis (Ph.D.)--Tufts University, 2003.<br>Adviser: David R. Walt. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;