Dissertations / Theses on the topic 'Micro-devices'

This thesis describes the design and development of novel micro analytical devices for application in on-line process analytics. The work describes the design, development, numerical simulation and application of these devices for two specific cases: (i) electrochemical detection of bio(chemical) species at micro-scale and (ii) separation and purification of biological reagents using immobilised metal affinity chromatography at micro-litre scale. Chapter 1 provides a general overview and background to the field of process analytics, microreactors and theory related to the mass transfer inside the electrochemical microfluidic devices and meso-chromatography columns. Chapter 2 provides an overview of microfabrication methods and the numerical simulations employed for the development of micro analytical devices used in this thesis. Chapter 3 describes an experimental voltammetric study of enzyme cofactors in batch and hydrodynamic systems and also provides a numerical investigation of mass transfer over electrodes inside microreactors. Chapter 4 investigates the effect of hydrodynamic focusing within a microfluidic device in detail, using experimental and numerical techniques. The quantification of the results was carried out using a pseudo two-dimensional, steady state backward implicit finite difference model. A series of studies, interrogating the effects of volumetric flow rate, volume ratio and lead-in length, were carried out to quantitatively investigate hydrodynamic focusing. Chapter 5 details the development and fabrication of patterned photopolymerised and electrochemically polymerised (conducting) monoliths with dimensions in the range of 100-1000μm. The photopolymerised monoliths were characterised using hydrodynamic methods in order to study the flow profile. Electrochemical techniques were used to characterise the conducting monoliths and its composites, using N,N,N’,N’-tetramethyl-p-phenylenediamine. Chapter 6 describes an application of the photopatterned monoliths. A meso-chromatography column was fabricated and immobilised metal affinity chromatography at meso and micro-litre scale was studied inside these columns. Proteins with polyhistidine tags were shown to be successfully separated, purified and quantified under batch and hydrodynamic conditions.

Narrowly dispersed amino-functionalised polystyrene microspheres, with a range of diameters, were successfully synthesised via emulsion and dispersion polymerisation. Fluorescent labelling allowed cellular translocation to be assessed in a variety of cell lines and was found to be very high, but controllable, whilst exhibiting no detrimental effect on cellular viability. In order to fully determine the mode of microsphere uptake, “beadfected” melanoma (B16F10) cells were studied using both chemical and microscopic methods. Uptake was found to be wholly unreliant upon energetic processes, with microspheres located cytoplasmically and not encapsulated within endosomes, an important characteristic for delivery devices. In order to demonstrate the effective delivery of exogenous cargo mediated by microspheres, short interfering (si)-RNAs were conjugated to beads and investigated for the gene silencing of enhanced green fluorescent protein (EGFP) in cervical cancer (HeLa) and embryonic (E14) stem cells. EGFP knockdown was found to be highly efficient after 48 – 72 hours. Dual-functionalised microspheres displaying a fluorophore (Cy5) and siRNA allowed only those cells beadfected with the delivery vehicle (and thus containing siRNA) to be assessed for EGFP expression, yielding an accurate assessment of microsphere-mediated gene silencing. In addition, by manipulation of the microsphere preparation conditions, micro-doughnuts and paramagnetic microspheres were produced and their cellular uptake assessed. Paramagnetic microspheres were found to enter cells efficiently and were subsequently used to bias the movement of beadfected cells in response to an externally applied magnet, while micro-doughnuts were found to exhibit cell selective properties and were noted to traffic specifically to the liver in vivo.

Confronted with the global demographic changes and the increasing pressure on modern healthcare system, there has been a surge of developing new technology platforms in the past decades. Droplet microfluidics is a prominent example of such technology platforms, which offers an efficient format for massively parallelized screening of a large number of samples and holds great promise to boost the throughput and reduce the costs of modern biomedical activities. Despite recent achievements, the realization of a compact and generic screening system which is suited for resource-limited settings and point-of-care applications remains elusive. To address the above challenges, the dissertation focuses on the development of a compact multifunctional droplet micro-magnetofluidic system by exploring the advantages of magnetic in-flow detection principles. The methodologies behind a novel technique for biomedical applications, namely, magnetic in-flow cytometry have been put forth, which encompass magnetic indexing schemes, quantitative multiparametric analytics and magnetically-activated sorting. A magnetic indexing scheme is introduced and intrinsic to the magnetofluidic system. Two parameters characteristic of the magnetic signal when detecting magnetically functionalized objects, i.e. signal amplitude and peak width, providing information which is necessary to perform quantitative analysis in the spirit of optical cytometry has been proposed and realized. Magnetically-activated sorting is demonstrated to actively select individual droplets or to purify a population of droplets of interest. Together with the magnetic indexing scheme and multiparametric analytic technique, this functionality synergistically enables controlled synthesis, quality administration and screening of encoded magnetic microcarriers, which is crucial for the practical realization of magnetic suspension arrays technologies. Furthermore, to satisfy the needs of cost-efficient fabrication and high-volume delivery, an approach to fabricate magnetofluidic devices on flexible foils is demonstrated. The resultant device retains high performance of its rigid counterpart and exhibits excellent mechanical properties, which promises long-term stability in practical applications.

In this PhD thesis the development of laser-based processes for packaging applications in microsystems technologies is investigated. Packaging is one of the major challenges in the fabrication of micro-electro-mechanical systems (MEMS) and other micro-devices. A range of bonding processes have become established in industry, however, in many or even most cases heating of the entire package to the bonding temperature is required to effect efficient and reliable bonding. The high process temperatures of up to 1100°C involved severely limit the application areas of these techniques for packaging of temperature sensitive materials. As an alternative production method, two localised heating processes using a laser were developed where also the heat is restricted to the joining area only by active cooling. Silicon to glass joining with a Benzocyclobutene adhesive layer was demonstrated which is a typical MEMS application. In this laser-based process the temperature in the centre of the device was kept at least 120°C lower than in the bonding area. For chip-level packaging shear forces as high as 290 N were achieved which is comparable and some cases even higher than results obtained using conventional bonding techniques. Furthermore, a considerable reduction of the bonding time from typically 20 minutes down to 8 s was achieved. A further development of this process to wafer-level packaging was demonstrated. For a simplified pattern of 5 samples the same quality of the seal could be achieved as for chip-level packaging. Packaging of a more densely packed pattern of 9 was also investigated. Successful sealing of all nine samples on the same wafer was demonstrated proving the feasibility of wafer-level packaging using this localised heating bonding process. The development of full hermetic glass frit packaging processes of Leadless Chip Carrier (LCC) devices in both air and vacuum is presented. In these laser-based processes the temperature in the centre of the device was kept at least 230°C below the temperature in the joining region (375°C to 440°C). Testing according to MIL-STD-883G showed that hermetic seals were achieved in high yield processes (>90%) and the packages did withstand shear forces in excess of 1 kN. Residual gas analysis has shown that a moderate vacuum of around 5 mbar was achieved inside the vacuum packaged LCC devices. A localised heating glass frit packaging process was developed without any negative effect of the thermal management on the quality of the seal.

Photonic devices are key to implement future communication and information technologies. Their success is largely determined by our capability to appropriately control light in such devices, especially in future reconfigurable networks. Light does not interact with itself, thus one usually needs the use of an active material. Phase change materials are a potential candidate to implement this functionality. These materials are a group of chemical compounds that exist in more than one stable phase, each with largely different electrical and optical properties. Moreover, they can be rapidly and reversibly switched between these phases using electrical or optical pulses. This thesis is devoted to the design and implementation of micronano structured photonic devices incorporating the phase-change material Ge2Sb2Te5 (GST). The thesis first investigates how to fabricate thin films of different phase-change materials in a repeatable manner and characterizes their main properties, especially those of GST. This includes an investigation of their composition, the conditions required to reversibly switch between the amorphous and crystalline phases, as well as their optical properties in each of the stable phases. Three different applications are then demonstrated, each of them based on a different functionality. The first application is an optical switch operating at telecommunication wavelengths. The device is implemented using a racetrack resonator partially covered with GST. The transmission resonances present in this system are controlled using an infrared laser that triggers phase transitions in the GST layer, thus modifying the shape and position of the resonance wavelength between two states. The switch has an on/off ratio of _ 12dB and response times of ~5μs. In the second application, control of surface plasmon polaritons in Au waveguides is demonstrated. This is achieved using a cladding layer of GST. 100 % modulation is achieved for large GST areas and thermal crystallization, while up to 30 % modulation is achieved using small GST areas and laser crystallization. The third application is related to nanohole arrays covered with GST thin films. The effect of phase transitions in the transmission resonances of these structures is investigated for three geometries. Wavelengths shifts as large as 385 nm are demonstrated in devices with broad resonances. Additionally, excitation of GST with short pulses allows for ultrafast tuning of these resonances in the ps regime without the need for a phase transition. Finally, tuning of narrow resonances with shifts of 13 nm is also shown.In summary, the studies and applications contained in this thesis demonstrate the potential of GST and, in general, phase-change materials, to address optical tunability, which is an essential function in a wide range of optical devices.
Els dispositius fotònics són un dels principals candidats per implementar les futures tecnologies de la informació i de la comunicació. El seu èxit dependrà en gran mesura de la capacitat de controlar la llum en aquests dispositius, en particular en dispositius reprogramables. Degut a que la llum no interactua amb ella mateixa normalment es necessita usar un material actiu per assolir aquest control. Els materials de canvi de fase són un dels possibles candidats per implementar aquesta funcionalitat. Aquest conjunt de compostos químics es caracteritzen per tenir més d’una fase estable. Cada una d’aquestes fases presenta unes propietats òptiques I elèctriques molt diferents. A més a més els canvis de fase en aquests materials es poden realitzar molt ràpidament i de manera reversible mitjançant polsos elèctrics o òptics. Aquesta tesis descriu el disseny i la implementació de nous dispositius òptics micro i nanoestructurats usant el material de canvi de fase Ge2Sb2Te5 (GST). A la primera part de la tesis s’investiga com fabricar capes primes de diferents materials de canvi de fase de manera repetible i es caracteritzen les seves propietats principals, en especial les del GST. Això inclou una investigació de la seva composició, les condicions necessàries per induir reversiblement transicions de fase entre els estats amorf i cristal·lí, així com mesures de les propietats òptiques de cada una de les fases. Aquests resultats es faran servir per implementar després tres aplicacions, cada una de les quals té una funció diferent. La primera aplicació és un interruptor òptic que treballa a una longitud dona de 1550 nm. El dispositiu està implementat en un anell ressonador parcialment recobert amb una capa prima de GST. Les ressonàncies en iv transmissió d’aquest sistema són controlades amb un làser infraroig que indueix transicions de fase en la capa de GST, modificant la forma i posició de la ressonància entre dos estats. L’interruptor té una relació entre els estats “on” i “off” de 12 dB i un temps de resposta d’uns 5 s. En la segona aplicació es demostra el control de plasmons de superfície propagant-se a través d’una guia d’ona d’or. Això s’aconsegueix fent servir una capa de GST dipositada sobre el dispositiu. Usant grans àrees de GST i cristal·lització per temperatura es poden aconseguir modulacions del 100 %, mentre que usant petites àrees de GST i cristal·lització làser es demostren modulacions de fins el 30 %. La tercera aplicació explora la combinació d’estructures periòdiques de nanoforats amb capes de GST. En aquest experiment s’investiga l’efecte de les transicions de fase en les ressonàncies de transmissió usant tres geometries diferents. En dispositius amb ressonàncies amples es poden desplaçaments en la longitud d’ona d’aquestes ressonàncies de 385 nm. A més a més, excitant la capa de GST amb polsos curts es mesuren canvis d’aquestes ressonàncies en una escala de temps de ps sense la necessitat d’induir una transició de fase. Per últim també es demostren desplaçaments en la longitud d’ona de fins a 13 nm en dispositius amb ressonàncies estretes. Els estudis i aplicacions descrits en aquesta tesi demostren el potencial del GST i dels materials de canvi de fase en general per implementar dispositius òptics sintonitzables, que realitzaran una funció essencial en futures tecnologies basades en la llum.

Aquest document resumeix el treball d'investigació realitzat per l'obtenció del títol de Doctor en Enginyeria Electrònica a la Universitat Autònoma de Barcelona (UAB).
El treball ha estat elaborat al Centre Nacional de Microelectrònica (CNM), a l'Institut de Microelectrònica de Barcelona (IMB).
Les activitats del CNM-IMB estan dividides en 6 àrees d'investigació diferents, cobrint un ampli rang de dispositius microelectrònics: microsistemes i tecnologia de silici, transductors químics, dispositius i sistemes de potència, aplicacions biomèdiques, diseny de circuits electrònics i nanotecnologia. Aquest treball s'ha dut a terme dins d'aquesta última àrea.
La major part de la feina s'ha emmarcat en el projecte d'investigació europeu FP6 NOVOPOLY (Novel functional polymer materials for MEMS and NEMS applications) que té com a objectius desenvolupar nous materials per aplicacions en l'àrea de la tecnologia dels micro- i dels nano- sistemes (MEMS i NEMS). Una altra part de la Tesi es va realitzar en el marc del projecte d'investigació europeu FP6 NaPa (Emerging Nanopatterning Methods) que pretén desenvolupar noves tècniques d'estampació nanomètrica com poden ser el NIL, soft lithography, la litografia basada en MEMS, etc. Ambdós projectes han estat fonts de motivacions, capital per recursos y col·laboradors que han contribuït notòriament en la formació d'aquesta Tesi.
El primer objectiu d'aquest treball va ser el de establir les bases de la tecnologia de fabricació amb polímers en la Sala Blanca del CNM. El CNM sempre ha treballat amb tecnologia de silici però, donat que el polímers estan demostrant ser una alternativa de baix cost, era interessant (a nivell local) optimitzar aquests processos.
Per altra banda, existeix un gran interès en modificar els polímers fotoestructurables existents, com la SU-8, afegint-los diferents funcionalitats i superant així les actuals limitacions d'aquests materials pel que fa a les seves propietats mecàniques, a la seva conductivitat elèctrica, a millorar la seva estabilitat a altes temperatures, etc. Aquests nous polímers poden representar en un futur pròxim les bases de l'avanç de la tecnologia de polímers, tant per aplicacions acadèmiques com industrials. Gràcies a les col·laboracions establertes en els projectes europeus abans mencionats, s'ha pogut presentar en aquesta Tesi el processat d'alguns nous polímers per algunes aplicacions concretes.
Per tots aquests motius esmentats, aquesta Tesi és un compendi de diferents dispositius polimèrics, cadascun d'ells fabricat amb processos diferents, perquè o bé els materials o bé les tècniques no eren les mateixes. Per aquesta raó, la Tesi es divideix en 7 Capítols:
La introducció pretén repassar l'estat de l'art de les tècniques de fabricació amb polímers. Com aquesta Tesi està enfocada en l'ús de polímers fotoestructurables per a la fabricació de dispositius, el principal procés és la UV lithography tot i que altres mètodes han estat desenvolupats per assolir millor resolució i millors resultats. Les tècniques litogràfiques que es poder utilitzar amb polímers estan breument descrites i també s'introdueixen tres tipus diferents de polímers per donar un coneixement bàsic dels conceptes més fets servir al llarg d'aquesta memòria.
El Capítol 2 presenta la fabricació de sondes d'AFM polimèriques que podes ser utilitzades en qualsevol equip d'AFM comercial, demostrant així el seu camp d'aplicació, el seu baix cost de producció i la seva capacitat per a ser comercialitzades. Aquesta és la principal responsabilitat de què el CNM tenia dins del projecte Novopoly.
El Capítol 3 és una extensió del capítol anterior però usant un nou material compost per nanopartícules i polímer. El nou material millora algunes de les propietats del polímer original i també s'afegeixen propietats que abans no tenia com pot ser l'actuació magnètica.
En el Capítol 4 s'introdueix un nou polímer. En aquest cas, es demostra que el material és capaç de proporcionar actuació optotèrmica degut a que té un coeficient d'expansió tèrmic més elevat que la versió no dopada. A més, donat que el material és negre, l'actuació òptica en el espectre del visible és possible, el que obre noves possibilitats comparat amb el polímer estàndard. Un model teòric i un estudi complert del comportament d'aquesta actuació estan detallats.
El Capítol 5 descriu com definir estructures de polímer utilitzant l'ink-jet printing i la soft-lithography. Aquestes dues tècniques han estat emprades per evitar la contaminació creuada entre els dipòsits d'un, prèviament fabricat, xip de microfluídica. Aquest capítol és un clar exemple de la flexibilitat que ofereix la tecnologia de polímer.
Les tècniques d'Scanning Probe Lithography (SPL), Litografia per Feix d'Electrons (EBL) i la litografia UV es poden combinar per imprimir en fines capes de polímers tal i com es descriu en el Capítol 6. En aquest capítol s'inclouen els detalls del mecanisme de modificació local del polímers fent servir el Microscopi de Forces Atòmiques (AFM).
Finalment, aquesta Tesi acaba amb les conclusions que estan resumides en el Capítol 7. En ell es comenten els principals resultats de cada un dels processos de fabricació desenvolupats en aquesta memòria.
Este documento resume el trabajo de investigación realizado para la obtención del título de Doctora en Ingeniería Electrónica en la Universitat Autònoma de Barcelona (UAB).
El trabajo ha sido elaborado en el Centro Nacional de Microelectrónica (CNM), en el Instituto de Microelectrónica de Barcelona (IMB).
Las actividades del CNM-IMB están divididas en 6 áreas de investigación diferentes, cubriendo un amplio rango de dispositivos microelectrónicos: microsistemas y tecnología de silicio, transductores químicos, dispositivos y sistemas de potencia, aplicaciones biomédicas, diseño de circuitos electrónicos y nanotecnología. Este trabajo se ha ejecutado dentro de esta última área.
La mayor parte del trabajo se ha elaborado en el marco del proyecto de investigación europeo FP6 NOVOPOLY (Novel functional polymer materials for MEMS and NEMS applications) que tiene como objetivos desarrollar nuevos materiales para aplicaciones en el área de la tecnología de los micro- y de los nano- sistemas (MEMS y NEMS). Otra parte de la Tesis se realizó en el marco del proyecto de investigación europeo FP6 NaPa (Emerging Nanopatterning Methods) cuya meta es el desarrollo de nuevas técnicas de estampación nanométrica como puede ser el NIL, soft lithography, la litografía basada en MEMS, etc. Ambos proyectos han sido fuentes de motivaciones, capital para recursos y colaboradores que han contribuido notoriamente en la formación de esta Tesis.
El primer objetivo de este trabajo fue el de establecer las bases de la tecnología de fabricación con polímeros en la Sala Blanca del CNM. El CNM siempre ha trabajado con tecnología de silicio pero, dado que los polímeros están demostrando ser una alternativa de bajo coste, era interesante (a nivel local) optimizar estos procesos.
Por otra parte, existe un gran interés en modificar los polímeros fotoestructurables existentes, como la SU-8, añadiéndoles diferentes funcionalidades y superar así las actuales limitaciones de estos materiales con respecto a sus propiedades mecánicas, a su conductividad eléctrica, a mejorar su estabilidad en altas temperaturas, etc. Estos nuevos polímeros pueden representar en un futuro próximo las bases del avance de la tecnología de polímeros, tanto para aplicaciones académicas como industriales. Gracias a las colaboraciones establecidas en los proyectos europeos antes mencionados, se ha podido presentar en esta Tesis el procesado de algunos nuevos polímeros para algunas aplicaciones concretas.
Por todos los motivos mencionados, esta Tesis es un compendio de diferentes dispositivos poliméricos, cada uno de ellos fabricado con procesos distintos, porque o bien los materiales o bien las técnicas no eran las mismas. Por esta razón, la Tesis se divide en 7 Capítulos:
La introducción pretende repasar el estado del arte de las técnicas de fabricación con polímeros. Como esta Tesis está enfocada en el uso de polímeros fotoestructurables para la fabricación de dispositivos, el principal proceso es la UV lithography aunque otros métodos han sido desarrollados para alcanzar mayor resolución y mejores resultados. Las técnicas litográficas que pueden ser usadas con polímeros están brevemente descritas y también se introducen tres tipos diferentes de polímeros para dar un conocimiento básico de los conceptos más usados a lo largo de esta memoria.
El Capítulo 2 presenta la fabricación de sondas de AFM poliméricas que pueden ser usadas en cualquier equipo de AFM comercial, demostrando así su campo de aplicación, su bajo coste de producción y su capacidad para ser comercializadas. Esta es la principal responsabilidad que el CNM tenía dentro del proyecto Novopoly.
El Capítulo 3 es una extensión del capítulo anterior pero usando un nuevo material compuesto por nanopartículas y polímero. El nuevo material mejora algunas de las propiedades del polímero original y también se añaden propiedades que antes no tenía como puede ser la actuación magnética.
En el Capítulo 4 se introduce otro nuevo polímero. En este caso, se demuestra que el material es capaz de proporcionar actuación optotérmica debido a que tiene un mayor coeficiente de expansión térmica que la versión no dopada. Además, dado que el material es negro, la actuación óptica en el visible es posible, lo que abre nuevas posibilidades comparado con el polímero estándar. Un modelo teórico y un estudio completo del comportamiento de esta actuación están detallados.
El Capítulo 5 describe cómo definir estructuras de polímero usando el ink-jet printing y la soft-lithography. Estas dos técnicas han sido usadas para evitar la contaminación cruzada entre los depósitos de un previamente fabricado chip de microfluídica. Este capítulo es un claro ejemplo de la flexibilidad que ofrece la tecnología de polímero.
Las técnicas de Scanning Probe Lithography (SPL), Litografía por Haz de Electrones (EBL) y la litografía UV se pueden combinar para imprimir en finas capas de polímeros tal y como se describe en el Capítulo 6. En este capítulo se incluyen los detalles del mecanismo de modificación local de polímeros usando en Microscopio de Fuerzas Atómicas (AFM).
Finalmente, esta Tesis termina con las conclusiones que están resumidas en el Capítulo 7. En él se comentan los principales resultados de cada uno de los procesos de fabricación desarrollados en esta memoria.
This document summarizes the research work performed in order to obtain the Ph.D. degree in Electronic Engineering at the Universitat Autònoma de Barcelona (UAB).
The work has been done at the National Centre for Microelectronics (Centro Nacional de Microelectrónica CNM), at the Institute of Microelectronics in Barcelona (IMB).
CNM-IMB activities are divided into 6 different research areas covering a wide range of microelectronic devices: microsystems and silicon technology, chemical transducers, power devices and systems, biomedical applications, electronic circuits design and nanotechnology. The present work has been performed in the latter area.
Most of the work has been performed in the frame of the FP6 European research project NOVOPOLY (Novel functional polymer materials for MEMS and NEMS applications) which aims to develop new functional materials for applications in the area of micro- and nano- systems technology (MEMS and NEMS). Also, a part of the thesis was performed within the frame of the FP6 European research project NaPa (Emerging Nanopatterning Methods) which aims the development of novel nanopatterning techniques as can be NIL, soft lithography, MEMS-based lithography, etc. Both projects have been source of funding, motivations and collaborators that have contributed notoriously to the development of this Thesis.
The first objective of the project was to establish the basis for polymer fabrication technology in the CNM Clean Room. CNM has always been working on silicon technology but, provided that polymer technology is showing itself as a low-cost alternative, it was interesting (at a local level)
to optimize these processes.
On the other hand, there is a large interest in adding functionality to existing photostructurable polymers, like SU-8, and overcome the current limitations of these systems with respect to mechanical, electrical conductivity and high temperature stability properties. These novel polymers can represent in the near future a cornerstone in the development of polymer technology, with both academic and industrial applications. Taking profit of some collaborations established in the projects mentioned above, the processing of some novel polymers is also presented in this Thesis for a few targeted applications.
Therefore, the Thesis is a compendium of different polymeric devices, each of them fabricated with a different process, because either the materials or the techniques were different; and the memory is divided in seven different chapters:
The introduction, aims to review the state of the art of polymer fabrication techniques. As this Thesis is focused in the use of photostructurable polymers for the fabrication of devices, the main process is the UV lithography although others methods have been developed in order to achieve higher resolution and better performance. Lithographic techniques usable for polymers are briefly described and the three kinds of polymers used are introduced in order to give the basic knowledge and main concepts used through all the work.
Chapter 2 presents the fabrication of usable polymeric AFM probes, demonstrating their field of application and low cost production and its feasibility to commercialization. This is the main activity that CNM had in Novopoly project.
Chapter 3 is an extension of the previous chapter but using a new composite material. The new material overcomes some of the drawbacks properties of the original epoxy based resist and also adds functional properties as it can be magnetic actuation.
In Chapter 4 another new composite is shown. In this case, optothermal actuation is demonstrated because this material has a higher thermal expansion coefficient than the undoped version. In addition, given the fact that the material is black, which means that optical actuation in the visible is possible, opening new possibilities compared with the standard polymer. A theoretical model and a fully study of the actuation behaviour is reported.
Chapter 5 describes polymer structures definition by ink-jet printing and soft-lithography. These two techniques were used to avoid the cross contamination between dispensing holes of a previously fabricated microfluidic chip. This chapter is itself an example of how flexible polymer technology is.
Scanning Probe Lithography (SPL), Electron-Beam Lithography (EBL) and UV lithography techniques have been combined to pattern thin layers of polymers as it is depicted in Chapter 6. This chapter includes details mechanism and operation of the local modification of polymers using an Atomic Force Microscope (AFM).
Finally, this Thesis ends with the conclusions that are summarized in Chapter 7. The main results of each fabrication process developed are commented.

This thesis reports on the design, fabrication and testing of microstructured devices for the manipulation of terahertz radiation. In particular, there is an emphasis on the fabrication and test of diffractive optics type components; including a surface micromachined, multilevel SU-8 based Fresnel lens and a micromilled aluminium Fresnel Zone Plate Reflector (FZPR). For both of these devices, the focal spot is characterized by measuring the electric field intensity and phase as a function of distance along the optical axis. This is carried out using a THz Vector Network Analyzer with associated free space optics. The results are compared directly with Finite Difference Time Domain simulations. A commercial FDTD solver, Lumerical, is used throughout the thesis. FDTD is first introduced for the design of antireflective subwavelength surfaces. These surface structures are bulk micromachined in silicon and their performance experimentally validated using THz Time-Domain Spectroscopy and Durham's THz VNA. A compact THz VNA based S11 measurement configuration is presented which uses the FZPR and a single parabolic mirror. This reflection configuration is used for the characterization of liquid samples (e.g. water and Isopropyl Alcohol mixtures) in microfluidic channels. Two types of channels are presented; one is formed using bulk micromachined silicon whereas the other type uses acetate films to create low cost, disposable devices. The results from the compact measurement configuration are compared with those obtained using a more conventional four parabolic mirror transmission arrangement (as found in THz Time-Domain Spectroscopy systems). Even in the compact configuration, the alignment of the components is found to be a significant factor in determining the measurement performance. Consequently, a six-axis micropositioner (Hexapod), is used to automatically sweep the reflector with the aim of producing a self-aligning system.

A biosensor is an analytical device integrating a biological element and a physicochemical transducer that convert a biological response into a measurable signal. The advantages of biosensors include low cost, small size, quick, sensitivity and selectivity greater than the conventional instruments. Biosensors have a wide range of applications ranging from clinical diagnostics through to environmental monitoring, agriculture industry, et al. The different types of biosensors are classified based on the sensor device as well as the biological material. Biosensors can be broadly classified into (piezoelectric, etc.), electrochemical biosensors (potentiometric, amperometric, etc.), and optical types of biosensors (fiber optics, etc.). Here, we introduce a novel microfluidics-integrated biosensor platform system that can be flexibly adapted to form individual biosensors for different applications. In this dissertation, we present five examples of different emerging areas with this biosensor system including anti-cancer drug screening, glucose monitoring, heavy metal elements measurement, obesity healthcare, and waterborne pathogen DNA detection. These micro-biosensors have great potential to be further developed to emerging portable sensing devices especially for the uses in the developing and undeveloped world. At the last chapter, Raman spectroscopy applied to assess gestational status and the potential for pregnancy complications is presented and discussed. This technique could significantly benefit animal reproduction.

In this project, Inductively Coupled Plasma (ICP) etching of natural and synthetic diamond using oxygen-based (Ar/0₂) and chlorine-based (Ar/Cl₂) plasmas was investigated. The effects of ICP platen and coil powers and gas pressures on the diamond etching were also studied. It was demonstrated that the diamond etch rate and etch selectivity using Ar/Cl₂ plasma etching, with high etch controllability (on the nanometre scale) and capabilities of removing the sub-surface damage and improving the surface smoothness, is only half of those by using Ar/0₂ plasma. Based on these studies, various diamond micro-optics including diamond microspherical positive and negative lenses, micro-cylindrical and micro-ring lenses, complex micro-lenses and optical gratings were designed and successfully fabricated. Structural and optical characterisations revealed the high optical quality and functionality of the fabricated diamond micro-optics. Applications of diamond micro-optics, such as micro-lensed micro-VECSEL photonic devices were also demonstrated. Utilising ICP Ar/Ch plasma etching and other processes, prototype diamond electronic devices such as diamond MISFETs and MOSFETs have been fabricated. To realize such diamond FET devices, ohmic contacts with low specific contact resistances, which can be achieved by applying aqua regia surface treatment and laser ablation techniques on the p-doped diamond, are imperative. However, it was found that the gate leakage currents of the diamond MISFET devices were quite large due to leakage through the diamond intrinsic layer under the gate. To overcome this problem, diamond MOSFET devices employing Si0₂ as gate insulation material were developed, which were able to sustain large gate biases with very low leakage currents. However, these diamond MOSFET devices could not be fully pinched-off which may be due to the high boron concentration and relatively thick delta layer, which leads to excessive charge in the channel of the device. By fabricating a recess gate diamond p-MOSFET, gate field control was much enhanced.

In this thesis we have investigated and proposed acoustic superLattices (ASLs) made of periodically poled ZX-cut lithium niobate (PPLN) associated ith coplanar electrodes as an effective alternative for surface acoustic wave (SAW) generation. In order to examine the acoustic transduction in the SL transducer we have developed and employed two modeling techniques. i.e . scalar approximation and finite element method (FEM) analysis (2-D nd 3-D modeling) implemented in COMSOL MULTIPHYSICS. Both techniques give similar results with respect to the characteristics of generated SAW modes. The calculated results obtained with the 3-D FEM simulation confirmed the Rayleigh nature of the generated SAW, showing that the excited SAW in the ASL is similar to that of the standard interdigitated transducer (IDT). From the propagation analysis in 2-D FEM simulation. we obtained that in addition to the SAW, the ASL transducer excites longitudinal bulk acoustic wave (L-BAW). Moreover. the 2-D model showed that the SAW excited by the ASL transducer does not propagate but it is rather confined within the transducer. Several ASL transducers, with different lattice periods, have been realized and characterized, also to validate the modeling and design tools . One and two-portelectrical measurements have been performed to evaluate the electro-acoustic response. In addition laser interferome try has been carried out o determine the out-of-plane component of the SAW displacement. With respect to the standard IDT configuration using the same crystal orientation, he efficiency of the SAW generation in the proposed designs is similar, while, for the same grating period, the resonance frequency that can be achieved is two times larger. In addition to the SAW, unlike its lOT counterparts, the ASL transducer can excite the L-BAW, as it had been predicted by the modeling. The two-port measurements have shown that the SAW signal collected at the receiver is small, indicating that the SAW energy remains essentially confined within the transmitter. This experimental result too is in agreement with the aforementioned theoretical predictions. After the experimental validation of the modeling, we designed and fabricated acousto-optic (AO) filters incorporating the ASL transducer. ASL struc tures with 20 tm period and coplanar electrodes have been realized along with 6 m wide Ti-LiNb03 optical channel waveguide. In that way monolithic and integrated (waveguide) SAW based AO filters and L-BAW based bulk AO filters have been demonstrated. As for integrated SAW based 0 filter, a 3-dB optical bandwidth of 2.5 nm, center wavelength of 1456 nm, and -20 dB distance of 14.49 nm are obtained at the SAW resonance frequency of 189.94 MHz. Such filter requires 1 W RF power to achieve nearly complete polarization conversion. As for the bulk AO filter. a center Wavelength of 1472.5 nm is measured at the L-BAW resonance frequency of 328 MHz. In the bulk AO filter. full conversion cannot be reached even at RF power up to 2 W. Comparing to the integrated (waveguide) filter. the efficiency of the bulk filter is significantly lower. The AO filter's central wavelength can be tuned by changing the RF power. We investigated several designs to improve the AO filter efficiency. By optimizing the ASL transducer (coplanar electrodes with electrode width of 70 urn and gap of 20 t m), nearly complete optical switching at very low electrical powers (50mW) has been obtained, this corresponding to an improvement factor of 20 compared to previous results. An appropriate mass-loading, placed on the surface and in between the electrodes of a coplanar LiNb03 ASL, has allowed achieving strong lateral confinement of the acoustic field, thus leading to a significant improvement of the AO filter performance.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1986.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Bibliography: leaves 48-52.
by Pamela Joan Adams.
M.S.

In order to develop more compact optical fiber sensing systems, modal filtering can be performed in-line by using micro-optical devices. Two such devices are a laterally offset few-moded optical fiber mechanical splice and a modal conversion optical fiber coupler. A third device, the air-gap splice used with multimode fibers, can examine the modal content of an optical fiber. A basic theoretical understanding on how these devices operate is reviewed. A splice loss calculation for few-moded optical fibers is presented. Applications of the asymmetrical few-moded mechanical optical fiber splice, the modal conversion coupler, and the air-gap splice are discussed.

Master of Science

This thesis investigates the use of micro-injection moulding (μIM), as a high-volume process, for producing three-dimensional, integrated microfluidic devices. It started with literature reviews that covered three topics: μIM of thermoplastic microfluidics, designing for three-dimensional (3-D) microfluidics and functional integration in μIM. Research gaps were identified: Designing 3-D microfluidics within the limitations of μIM, process optimisation and the integration of functional elements. A process chain was presented to fabricate a three-dimensional microfluidic device for medical application by μIM. The thesis also investigated the effect of processing conditions on the quality of the replicated component. The design-of-experiments (DOE) approach is used to highlight the significant processing conditions that affect the part mass taking into consideration the change in part geometry. The approach was also used to evaluate the variability within the process and its effect on the replicability of the process. Part flatness was also evaluated with respect to post-filling process parameters. The thesis investigated the possibility of integrating functional elements within μIM to produce microfluidic devices with hybrid structures. The literature reviews highlighted the importance of quality control in high-volume micromoulding and in-line functional integration in microfluidics. A taxonomy of process integration was also developed based on transformation functions. The experimental results showed that μIM can be used to fabricate microfluidic devices that have true three-dimensional structures by subsequent lamination. The DOE results showed a significant effect of individual process variables on the filling quality of the produced components and their flatness. The geometry of the replicated component was shown to have effect on influential parameters. Other variables, on the other hand, were shown to have a possible effect on process variability. Optimization statistical tools were used to improve multiple quality criteria. Thermoplastic elastomers (TPE) were processed with μIM to produce hybrid structures with functional elements.

Engineering and Physical Sciences Research Council
This thesis describes the development of a multi-objective automated optimisation system to be used for the design optimisation of micro-scale combustion devices. The developed system described within integrates a commercial computational fluid dynamics package and a multi-objective variant of the Tabu Search optimisation algorithm for continuous problems, which is a heuristic optimisation technique that exhibits local search characteristics. Recent advances in micro-fabrication techniques have resulted in increasing interest from industry and academia to investigate the possibility of replacing the current conventional power supply “battery” with a miniaturised combustion power generation system based on micro-electro-mechanical systems (MEMS) technology. The microcombustor is one of the crucial components of such a power system. The aim is to improve the main micro-scale combustor design characteristics and to satisfy manufacturability considerations from the very beginning of the whole design process. The main combustor design requirements, challenges and design parameters that influence the device performance at a micro-scale were first defined. Within the optimisation design cycle a robust parameterisation scheme, the geometry and numerical grid representations were implemented. These were achieved by incorporating the knowledge gained from the parametric design study by understanding the design space in depth and identifying issues and their solutions during this design study such as geometry overlapping and mesh refinement. Cont/d.

This thesis presents a study on the integration of polymer organic materials, onto GaN-based micron-scale light-emitting diodes, or 'micro-LEDs'. Several pertinent micro-patterning techniques are investigated along with their used in the realisation of such hybrid devices. Polymers are an attractive family of materials whose properties can be tailored to the requirements of specific applications. The interest of this thesis focuses on an 'in-house' synthesised transparent polymer ('HTP2') designed for encapsulation of micro-LEDs emitting in the UV-blue region of the spectrum and on conjugated light-emitting materials whose semiconducting properties are used in this work for colour conversion.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, February 2011.
"October 2010." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 140-147).
Rapid genome characterization is one of the grand challenges of genome science today. Although the complete sequences of certain representative human genomes have been determined, genomes from a much larger number of individuals are yet to be studied in order to fully understand genome diversity and genetic diseases. While current state-of-the-art sequencing technologies are limited by the large timescale and cost required to analyze a single sample, an alternative strategy termed DNA mapping has recently received considerable attention. Unlike sequencing which produces single-base resolution, DNA mapping resolves coarse-scale (~kbp) information of the sequence, which is much faster and cheaper to obtain, but still sufficient to discern genomic differences among individuals within a given species. Advances in fluorescence microscopy have allowed the possibility to directly map a single DNA molecule. This concept, though straightforward, faces a major challenge that the entropic tendency of polymeric DNA to adopt a coiled conformation must be overcome so as to optically determine the position of specific sequences of interest on the DNA backbone. The ability to control and manipulate the conformation of single DNA molecules, especially, to stretch them into a linear format in a consistent and uniform manner, is thus crucial to the performance of such mapping devices. The focus of this thesis is to develop a reliable single DNA stretching device that can be used in single molecule DNA mapping, and to experimentally probe the fundamental physics that govern DNA deformation. In the aspect of device design, the strategy we pursue is the use of an elongational electric field with a stagnation point generated in the center of a cross-slot or T channel to stretch DNA molecules. The good compatibility of electric field with small channel dimensions allows us to use micro- or nano-fabricated channels with height on the order of or smaller than the natural size of DNA to keep the molecule always in focus, a feature desirable for any mapping applications. The presence of the stagnation point allows the possibility to dynamically trap and stretch single DNA molecules. This trapping capability ensures uniform stretching within a sample ensemble, and also allows prolonged imaging time to obtain accurate detection results. We primarily investigate the effects of channel height on the stretching process, specifically, we seek the possibility of utilizing slit-like nanoconfinement to aid DNA stretching. Although extensive previous studies have demonstrated that geometric confinement of DNA can substantially alter the conformation and dynamics of these molecules at equilibrium, no direct studies of this non-equilibrium stretching process in confinement exist prior to the work presented in this thesis. We find that slit-like confinement indeed facilitates DNA stretching by reducing the deformation Abstract rate required to achieve a certain extension. However, due to the fact that the steric interactions between the DNA and the confining walls vanish at large extensions, highly stretched DNA under confinement behaves qualitatively similar to unconfined DNA except with screened hydrodynamic interactions, and a new time scale arises that should be used to describe the large change in extension with applied deformation rate. In a consecutive study, we examine the low-extension stretching process and observe a strongly modified coil-stretch transition characterized by two distinct critical deformation rates for DNA in confinement, different from the unconfined case where a single critical deformation rate exists. With kinetic theory modeling, we demonstrate that the two-stage coilstretch transition in confinement is induced by a modified spring force law, which is essentially related to the extension-dependent steric interactions between DNA and the confining walls. We also study aspects of the equilibrium conformation and dynamics of DNA in slit-like confinement in order to provide insight into regimes where existing studies show inconsistent results. We use both experiments and simulations to demonstrate that the in-plane radius of gyration and the 3D radius of gyration of DNA behaves differently in weak confinement. In strong confinement, we do not identify any evident change in the scalings of equilibrium size, diffusivity, and longest relaxation time of the DNA with channel height from the de Gennes regime to the Odijk regime. Although the transition between the de Gennes and Odijk regimes in slit-like confinement still remains an open question, our finding adds more experimental evidence to the side of a continuous transition. The impact of this thesis will be two-fold. We design a DNA stretching device that is readily applicable to single molecule DNA mapping and establish guidelines for the effective operation of the device. Our fundamental results regarding both the equilibrium and non-equilibrium dynamics of DNA molecules in slit-like confinement will serve as a solid basis for both the design of future devices aiming to exploit confinement to manipulate biopolymers, and more complicated studies of confined polymer physics.
by Jing Tang.
Ph.D.

Afin de pouvoir profiter de services sécurisés, efficaces et rapides (ex: paiement mobile, agenda, télécommunications, vidéos, jeux, etc.), de nos jours nos téléphones embarquent trois différents microcontrôleurs. Du plus sécurisé vers le plus générique nous avons, la carte SIM qui n’est autre qu’une carte à puce sécurisé chargée de garder de manière sûr au sein de sa mémoire des données sensibles. Ensuite, nous avons le processeur à bande de base qui est le seul à pouvoir discuter avec la carte SIM, et s’occupe de se charger des fonctions radio du téléphone (ex: le réseau GSM/3G/4G/LTE). Et enfin, nous avons le processeur applicatif, qui se charge d’exécuter tous les autres programmes sur le téléphone. Ce qui rend ces microcontrôleurs plus particuliers, c’est le fait qu’ils sont chacun contrôlés par un système d’exploitation totalement indépendant. Néanmoins, chacun peut avoir son influence, direct ou indirect sur l’autre/les autres. La sécurité de ces trois plateformes dépendent non seulement de leur implémentations matérielles, mais aussi de l’implémentation logicielle de leur système d’exploitation. Cette thèse s’intéresse à la sécurité logicielle, et en partie, matérielle de ces trois plateformes, afin de comprendre dans quelle mesure, une carte à puce telle que la carte SIM, est-elle résistante aux attaques logicielles dans le contexte d’un environnement multi-applicatif offert par les appareils mobiles. Nous nous intéressons aussi, à la sécurité du processeur applicatif face à une famille particulière d’attaque qui exploite le mécanisme de mémoire cache. Nous partons alors de l’étude et de l’application en pratique des attaques logiques sur carte à puce. Après avoir étudié les différents moyens qui permettent d’atteindre la carte SIM dans un mobile et ainsi d’étudier la surface d’attaque, nous poursuivons vers une étude par rétro-conception de l’implémentation de l’interface logicielle qui communique directement avec la SIM au niveau du processeur de bande de base. Ceci afin de comprendre le fonctionnement de cette partie très peu documentée. Finalement, nous étudions les effets du mécanisme de cache sur l’exécution d’un programme dans un téléphone mobile. Enfin, nous avons commencé à étudier l’attaque de Bernstein, qui consiste à exploiter les variations de temps induits par différents mécanismes de cache, en mesurant le temps global de l’exécution d’une implémentation particulière de l’algorithme cryptographique AES (Advanced Encryption Standard). Plus particulièrement, par une mise en pratique, nous essayons de déterminer ce qui exacerbe ou non la réalisation de sa technique dans le contexte d’un téléphone mobile réel
Nowadays, in order to provide secure, reliable and performant services (e.g: mobile payments, agenda, telecommunication, videos, games, etc.), smartphones embed three different micro-controllers. From the most secure to the most general purpose one, we have the SIM card which is a secure smart card that has to prevent anyone by any means to exfiltrate sensitive assets from its internal memories. Furthermore, we also have the baseband processor, which is the only one that directly talks with the SIM card. It essentially manages all the "phone" parts (e.g: GSM/3G/4G/LTE networks) inside a mobile device. Finally, we have the application processor which runs all the general user applications. What is interesting to note for those three micro-controllers is that they are controlled by different and independent operating systems. However, one may affect the behavior of the other(s). The security of these three platforms depend on their hardware and software implementations. This thesis is concerned with the security of these three microcontrollers that are managed by independent OSs within mobile devices. We particularly focused on understanding to what extent a smart card such as SIM cards can be resistant to software attacks in the context of a multi-application environment provided by mobile devices. We were also interested in a specific family of, so-called cache attacks, namely time-driven one, as this kind of technique essentially exploits the hardware implementation of the different cache memories and the mechanisms that enable to manage them. We decided to first study and experimentally perform so-called logical attacks on smart cards. In a second step, in order to understand the attack surface, we have studied the different means to reach the SIM card from both the baseband processor and the application processor. Then, by means of reverse engineering, we tried to understand how was implemented the SIM interface from the baseband side. Finally, we have studied the cache effects on the execution speed of a program on real mobile devices, and we experimentally studied Bernstein’s time-driven cache attack in order to understand what possible events/mechanisms exacerbate (or not) the achievement of the latter on an actual mobile device

Micro-devices are developed for uses in targeted drug delivery and microscale manipulation. Here we numerically and analytically study two promising devices in early stages of development. Firstly, we study Armoured Microbubbles (AMBs) which can self-propel as artificial microswimmers or facilitate microfluidic mixing in a channel when held stationary on a wall. Secondly, we study an artificial cilium, which due to its unique design, when placed in an array, easily produces a metachronal wave for fluid transportation. The Armoured Microbubble was designed by our experimental collaborators (group of Philippe Marmottant, University Grenoble Alpes) and consists of a partial hollow sphere, inside which a bubble is caught. Under ultrasound the bubble oscillates, generating a streaming flow in the surrounding fluid and producing a net force. Motivated by the AMB but considering initially a general setup, using matched asymptotic expansions we calculate the streaming flow around a spherical body undergoing arbitrary, but known, small-amplitude surface shape oscillations. We then specialise back to the AMB and consider its excitation under ultrasound, using a potential flow model with mixed boundary conditions, to identify the resonant frequencies and mode shapes, including the dependence of the resonance on the AMB shape parameters. Returning to our general streaming model, we applied the mixed boundary conditions directly to this model, calculating the streaming around the AMB, in good agreement with experiments. Using hydrodynamic images and linear superposition, this model was extended to incorporate one wall, and AMB compounds. We then study the streaming flows generated by arrays of AMBs in confined channels, by modelling each AMB as its leading order behaviour (with corrections where required) and superposing the individual flow fields of all the AMBs. We identified the importance of two confining walls on the streaming flow around the array, and compared these flows to experiments in five cases. Motivated by this setup, we theoretically considered the extension of a two fluid interface passing through an AMB array to quickly identify good AMB arrays for mixing. We then studied the second artificial micro-device: an artificial cilium. Tsumori et. al. produced a cilium of PDMS containing aligned ferromagnetic filings, which beat under a rotating magnetic field. We modelled a similar cilium but assumed paramagnetic filings, using a force model balancing elastic, magnetic and hydrodynamic forces identifying the cilium beat pattern. This agreed with our equilibrium model and asymptotic analysis. We then successfully identified that the cilium applies the most force to the surrounding fluid at an intermediate value of the two dimensionless numbers quantifying the dynamics.

The emergence of Cyber Physical Systems (CPS) and Internet-of-Things (IoT) based principles and technologies holds the potential to facilitate global collaboration in various fields of engineering. Micro Devices Assembly (MDA) is an emerging domain involving the assembly of micron sized objects and devices. In this dissertation, the focus of the research is the design of a Cyber Physical approach for the assembly of micro devices. A collaborative framework comprising of cyber and physical components linked using the Internet has been developed to accomplish a targeted set of MDA life cycle activities which include assembly planning, path planning, Virtual Reality (VR) based assembly analysis, command generation and physical assembly. Genetic algorithm and modified insertion algorithm based methods have been proposed to support assembly planning activities. Advanced VR based environments have been designed to support assembly analysis where plans can be proposed, compared and validated. The potential of next generation Global Environment for Network Innovation (GENI) networking technologies has also been explored to support distributed collaborations involving VR-based environments. The feasibility of the cyber physical approach has been demonstrated by implementing the cyber physical components which collaborate to assemble micro designs. The case studies conducted underscore the ability of the developed Cyber Physical approach and framework to support distributed collaborative activities for MDA process contexts.

The rapid advancement of drug delivery systems (DDS) has raised the possibility of using functional engineered nano/micro-particles as drug carriers for the administration of active pharmaceutical ingredients (APIs) to the affected area. The major goals in designing these functional particles are to control the particle size, the surface properties and the pharmacologically active agents release in order to achieve the site-specification of the drug at the therapeutically optimal rate and dose regimen. Two different equipment (i.e. glass capillary microfluidic device and micro-engineered membrane dispersion cell) were utilised in this study for the formation of functional nano/micro-particles by antisolvent precipitation method. This method is based on micromixing/direct precipitation of two miscible liquids, which appear as a straightforward method, rapid and easy to perform, does not require high stirring rates, sonication, elevated temperatures, surfactants and Class 1 solvents can be avoided. Theoretical selection of a good solvent and physicochemical interaction between solvent-water-polymer with the aid of Bagley s two-dimensional graph were successfully elucidated the nature of anti-solvent precipitation method for the formation of desired properties of functional pharmaceutical nano/micro-engineered particles. For the glass capillary microfluidic experiment, the organic phase (a mixture of polymer and tetrahydrofuran/acetone) was injected through the inner glass capillary with a tapered cross section culminated in a narrow orifice. The size of nanoparticles was precisely controlled by controlling phase flow rates, orifice size and flow configuration (two- phase co-flow or counter-current flow focusing). The locations at which the nanoparticles would form were determined by using the solubility criteria of the polymer and the concentration profiles found by numerical modelling. This valuable results appeared as the first computational and experimental study dealing with the formation of polylactide (PLA) and poly(ε-caprolactone) (PCL) nanoparticles by nanoprecipitation in a co-flow glass capillary device. The optimum formulations and parameters interactions involved in the preparation of paracetamol encapsulated nanoparticles (PCM-PCL NPs) using a co-flow microfluidic device was successfully simulated using a 25-full factorial design for five different parameters (i.e. PCL concentration, orifice size, flow rate ratios, surfactant concentration and paracetamol amount) with encapsulation efficiency and drug loading percentage as the responses. PCM-loaded composite NPs composed of a biodegradable poly(D,L-lactide) (PLA) polymer matrix filled with organically modified montmorillonite (MMT) nanoparticles were also successfully formulated by antisolvent nanoprecipitation in a microfluidic co-flow glass capillary device. The incorporation of MMT in the polymer matrix improved the drug encapsulation efficiency and drug loading, and extended the rate of drug release in simulated intestinal fluid (pH 7.4). The encapsulation of MMT and PCM in the NPs were well verified using transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), x-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). PCL drug-carrier nanoparticles were also produced by rapid membrane micromixing combined with nanoprecipitation in a stirred cell employing novel membrane dispersion. The size of the NPs was precisely controlled by changing the aqueous-to-organic volumetric ratio, stirring rate, transmembrane flux, the polymer content in the organic phase, membrane type and pore morphologies. The particle size decreased by increasing the stirring rate and the aqueous-to-organic volumetric ratio, and by decreasing the polymer concentration in the aqueous phase and the transmembrane flux. The existence of the shear stress peak within a transitional radius and a rapid decline of the shear stress away from the membrane surface were revealed by numerical modelling. Further investigation on the PCL nanoparticles loaded immunosuppressive rapamycin (RAPA) drug were successfully synthesised by anti-solvent nanoprecipitation method using stainless steel (SS) ringed micro-engineered membrane. Less than 10 μm size of monohydrate piroxicam (PRX) micro-crystals also was successfully formed with the application of anti-solvent precipitation method combined with membrane dispersion cell that has been utilised in the formation of functional engineered nanoparticles. This study is believed to be a new insight into the development of integrated membrane crystallisation system.

In the last decades, energy requirements of portable devices are exponentially increasing while the capacity of the current battery technology is not progressing accordingly. This energy gap claims for the development of new technologies beyond Li-ion. Novel miniaturized devices able to efficiently operate on the low power regime (1 — 20 W) in continuous mode by using a fuel are receiving increased attention. Due to their long lifetime, high power density and integrability, probably the most promising alternative is the development of micro fuel cells. Amongst them, micro Solid Oxide Fuel Cells mi-SOFCs) present the highest values of specific energy densities (by unit mass and volume), mainly due to their higher operating temperature and their capability of operating directly on hydrocarbon fuels. One of the most promising approaches for the mi-SOFCs is based on the monolithic integration of functional free-standing electrolyte membranes in silicon technology. This approach ensures high reproducibility and reliability, cheap mass production and easy integration to mainstream technology. This thesis encompasses the design, fabrication and test of the main components of a novel mi-SOFC power generator as a first step to develop a complete device in the near future. The adopted approach is based on the use of MEMS fabrication methods to miniaturize mi-SOFCs in silicon technology and high energy density hydrocarbons as fuels. The mi-SOFC power generator is designed to supply 1W of electrical energy in a small volume (10-20 cm3). The work developed is divided into six chapters. The first chapter introduces the basics and challenges of a mi-SOFC power generator. The second chapter focuses on the experimental procedures and characterization techniques used. In the third chapter, the thermal analysis of a new mi-SOFC power generator with finite-volume simulations is presented. The fourth chapter shows the fabrication and characterization of a fuel processing unit capable to produce hydrogen from ethanol steam reforming and methane dry reforming. The next chapter is related to a catalytic micro-machined combustor. Finally, chapter six presents the development of a full ceramic mi-SOFC.
La demanda d'energia dels dispositius electrònics portàtils augmenta exponencialment any rere any, però la tecnologia actual amb les bateries d'ió liti no progressa suficientment. Aquesta divergència energètica és una oportunitat per poder desenvolupar noves tecnologies. En aquest sentit, micro dispositius que operin de forma contínua mitjançant l'ús d'un combustible i que proporcionin una potència compresa entre 1 i 20 W reben una especial atenció per part de la comunitat científica. Probablement, l'alternativa més prometedora són les micro piles de combustible, ja que tenen una llarga vida útil, una alta densitat de potència i són fàcils d'integrar. Dels diferents tipus, les piles de combustible d'òxid sòlid (mi-SOFCs) són les que tenen una major densitat específica d'energia (per unitat de massa i de volum). A més a més, treballen a una temperatura més alta i aquesta característica permet utilitzar hidrocarburs com a combustible. Una de les configuracions més esteses de les mi-SOFCs és la que es basa en membranes electrolítiques en suspensió, integrades amb la tecnologia de silici. Aquesta configuració permet una producció elevada, barata i fiable. La present tesi té com a objectiu dissenyar, fabricar i validar experimentalment els principals components d'un nou dispositiu generador. Els resultats obtinguts són un primer pas per desenvolupar en un futur proper un dispositiu complet basat en l'ús de MEMS (sistemes micro electromecànics) i hidrocarburs d' alta densitat d'energia. El dispositiu mi-SOFC ha estat ideat per subministrar 1W de potència elèctrica i ocupar un volum entre 10 i 20 cm3. La tesi consta de sis capítols. En el primer es descriuen els conceptes generals relacionats amb un dispositiu mi-SOFC i els principals reptes associats que presenta el seu desenvolupament. El segon es centra en els procediments experimentals i les tècniques de caracterització utilitzades al llarg de la tesi. El tercer capítol presenta l'anàlisi tèrmica del sistema proposat mitjançant simulacions termofluídiques. El quart mostra la fabricació i caracterització d'una unitat de processament de combustible capaç de produir hidrogen a partir del reformat d'etanol i metà. El cinquè descriu una unitat catalítica de combustió. I l'últim capítol, es centra en les capes funcionals d'una pila de combustible mi-SOFC completament ceràmica.

Thesis (Ph. D.)--University of California, San Diego, 2009.
Title from first page of PDF file (viewed July 9, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 155-161).

This thesis presents the application of two soft lithographic tools for direct patterning of (soft) photonic materials at the micro- and nano-scale. Inkjet printing and Dip-Pen Nanolithography, respectively, have been used to pattern organic molecules, photoresists, and conductive inks to create optically active structures and devices. A series of light emitting polymers (LEPs), blended with a photo-curable host system, have been integrated as colour converters with an array of matrix-addressable gallium nitride (GaN) micro LEDs to form a red-green-blue (RGB) emitting array. Surface structure and conversion efficiency have been explored in detail with peak colour conversion efficiencies of 31.6% being obtained. Inkjet printing of silver conductive inks has been used in conjunction with mask-free ultraviolet direct writing to generate an 8 x 8 GaN LED array. The smallest feature achieved with the mask-free writing set up is 1 μm and the conductive ink was used to form a contact with the n-GaN to enable wire-bonding and characterisation of the LED. This mask-free process is attractive as fabrication of conventional masks for photolithography is both costly and lengthy. Possessing the ability for define LED patterns “free form” on photoresist and subsequently producing a common n-contact with the silver ink allows for rapid prototyping for novel and experimental LED designs. Two techniques were explored for utilising the potential of Dip-Pen Nanolithography; deposition of liquid inks (positive) and removal of dried material (negative). Photoresist inks were used to generate nanoscale features (560nm) on a planar LED structure. Subsequent exposure to a CHF3 plasma treatment deactivated the Mg doped GaN which was not protected by the photoresist; LEDs with 3 μm diameter at full-width half-maximum were fabricated in this manner. Utilising dip-pen nanolithography for negative patterning allows for grating structures to be created via the displacement and removal of material. 1D and 2D structures were generated using a lasing polymer as the optically active gain medium. When optically pumped it was found that these structures lased and the grating structures acted as Distributed Bragg Reflectors (DBRs).Key advantages for the techniques used throughout this thesis are that they allow the patterning of sensitive materials that otherwise would not survive classical lithography due to aggressive chemical treatment or high UV exposure. In addition all of the techniques used are readily programmable and require no masks to be fabricated thus allowing for rapid prototype production and experimental designs to be implemented without delays or incurring extra costs.

Dans cette thèse, on présente des outils de modélisation pour étudier des structures à bandes interdites photoniques non-linéaires et des microcavités. Premièrement, une CMT et une BPM non linéaires ont été développées pour prouver la propagation de solitons spatiaux dans une structure périodique composée d'une série de guides droits. Suite à ces résultats théoriques notables, des fonctions actives sont envisagées grâce à ces régimes. Une autre méthode a ensuite été développée pour modéliser en trois dimensions des cavités optiques ayant une symétrie circulaire telles que des microdisques. La méthode est validée en comparant des résultats avec la FDTD. Il est aussi montré la possibilité de confiner le champ dans une couche de faible indice de réfraction insérée au milieu d'un microdisque de Silicium en gardant un fort coefficient de qualité et des petites volumes modales. Enfin, la caractérisation de microdisques en SOI avec des Q supérieures à 50000 est présentée
Ln this thesis we show several modelling tools which are used to study nonlinear photonic band-gap structures and microcavities. First of aIl a nonlinear CMT and BPM were implemented to test the propagation of spatial solitons in a periodic device, composed by an array of parallel straight waveguides. Ln addition to noteworthy theoretical considerations, active functionalities are possible by exploiting these nonlinear regimes. Another algorithm was developed for the three-dimensional modelling of photonic cavities with cylindrical symmetry, such as microdisks. This method is validated by comparison with FDTD. We aIse show the opportunity to confine a field in a region of low refractive index lying in the centre of a silicon microdisk. High Q-factor and small mode volumes are achieved. Finally the characterization ofmicrodisks in SOI with Q-factor larger than 50000 is presented

A material that is enabling integrated optics is the ferroelectric crystal Lithium Niobate (LiNbO3), which has excellent electro-optical, acousto-optical and nonlinear optical properties. Moreover, it can be doped with laser-active ions and allows for simple fabrication of low-loss optical waveguides. The broad aim of this work is to develop and introduce advanced micro- and nano-fabrication techniques for LiNbO3 and a new class of integrated based telecommunication and sensing devices. The techniques developed include precise micro-domain inversion, etching, bonding and thin film fabrication. From a device point of view, domain inversion is used to improve the electro-optic response of LiNbO3 waveguide modulators in terms of bandwidth and driving voltage. With respect to standard single-domain structures, larger bandwidths and lower driving voltages can be obtained, thus achieving figure of merits for the electro-optic response that are up to 50% larger. As a demonstration, a chirp-free modulator, having ~2V switching voltage and bandwidth of 15 GHz, was fabricated by placing the waveguide arms of a Mach-Zehnder interferometer in opposite do- main oriented regions. The modulator could be driven in a single-drive configuration with inexpensive low-voltage drivers, e.g. a SiGe based RF amplifier, typically used for electro-absorption devices. A further aspect of this work focuses on the development of devices for the precise measurement of strong electric fields, which are typically generated in power stations and transmission lines. Therefore, two new integrated electric field sensors are proposed, each of which exploits the aforementioned micro-fabrication techniques. The first device is based on a proton-exchange waveguide at cut-off, centered on a few microns wide domain-inverted region in a z-cut LiNbO3 substrate. The sensor’s performance is demonstrated by detecting DC fields up to 2.6 MV/m and high-frequency (1.1 GHz) fields ranging from 19 V/m to 23 kV/m. The second proposed device is fabricated by direct bonding a z-cut LiNbO3 substrate on top of a cut-off proton-exchanged waveguide centered on the domain-inverted region. It is possible to detect electric fields as high as 2 MV/m at low frequency with improved sensitivity compared to the previous device. These features make the devices suitable for use in high electric field and harsh conditions without endangering the operator. The conclusions section of the Thesis presents possible future developments which will contribute to increase the impact of the work in the optical telecommunication and sensing industries. After a brief introduction, the second chapter describes the basic properties of the material used in the thesis work: Lithium Niobate (LiNbO3). This includes the properties related to its ferroelectric crystal structure and the subsequent applications. Chapter three presents the micro-fabrication techniques, over 3 inch LiNbO3 wafers, developed at ICFO during this work. The chapter begins with a description of waveguides fabrication by Annealed Proton Exchange (APE). The mid-part of the chapter outlines the fabrication procedure for domain inversion using electric field poling technique and liquid electrodes while the last part describes the bonding technique to permanently join LiNbO3 with different substrates, namely Si, SiO2 and another LiNbO3. Moreover, lapping and polishing techniques for thin plate fabrication are presented. The forth chapter firstly introduces the fundamentals and main characteristics of travelling-wave LiNbO3 Mach-Zehnder modulators. Secondly, a new modulator design is proposed. It is based on domain inverted LiNbO3, with improved performance with respect to existing devices. The modulator characterization and the results obtained from the new design are presented. The chapter five begins with a literature review about DC and low frequency electric field optical sensors. Afterwards, two novel all-optical electric field sensors are presented. Both devices are based on a proton-exchange, domain inversion and bonding techniques. The sensors characterization, including the test set-up and the performance results are discussed. Finally, in chapter six, several conclusions on the thesis work and possible future work directions are presented.
Uno de los materiales que permite el avance de la tecnología de dispositivos ópticos integrados es el niobato de litio (LiNbO3). Se trata de un cristal ferro-eléctrico, con excelentes propiedades electro-ópticas, acusto-ópticas y no lineales. Además, es posible fabricar guías de onda de bajas pérdidas mediante las técnicas de intercambio protónico (PE) y difusión de titanio. El objetivo principal de este trabajo es el desarrollo y la introducción tanto de las técnicas avanzadas de micro-nano fabricación para el niobato de litio como de nuevos dispositivos ópticos integrados para las comunicaciones ópticas y la detección de campo eléctricos de alto voltaje. La técnicas de fabricación desarrolladas incluyen inversión de dominios mediante la técnica de poling de alto voltaje, grabado, bonding y capas delgadas. Desde el punto de vista de los dispositivos, la inversión de dominios ha sido utilizada para mejorar la respuesta electro-óptica de los moduladores en LiNbO3 en términos de ancho de banda (BW) y voltaje de control (Vπ). En comparación con los moduladores comerciales actuales de un único dominio, con esta técnica es posible obtener mayores anchos de banda y menores voltajes de control resultando en un aumento del 50% del producto BW·Vπ. Para demonstrar la eficacia de la técnica desarrollada, se ha fabricado un modulador Mach-Zehnder chirp-free poniendo los brazos del interferómetro en dos regiones de dominios opuestos. De las mediciones efectuadas se han obtenidos valores de voltaje de control de 2V y ancho de banda de 15 GHz. Estos resultados muestran que los dispositivos desarrollados pueden reducir el coste total de funcionamiento, ya que permiten el uso de controladores económicos de Si-Ge que operan en el rango de los 2V. Otro aspecto de este trabajo se enfoca en el desarrollo de dispositivos para medir, de forma exacta, altos campos eléctricos, que normalmente son generados en las centrales eléctricas y en las líneas de transmisión. Por este motivo, se han desarrollado dos sensores de campo eléctrico mediante las técnicas de micro-fabricación anteriormente mencionadas. El primer dispositivo está basado en una guía fabricada mediante intercambio protónico en LiNbO3 z-cut, diseñada a la frecuencia de corte y centrada en una región de dominio invertido de 10 micras de ancho y 10mm de largo. El rendimiento del dispositivo se ha demostrado detectando campos a baja frecuencia con amplitudes de hasta 2.6MV/m y campos a la frecuencia de 1.1GHz con amplitudes desde 19V/m hasta 23kV/m. El segundo dispositivo se ha fabricado mediante bonding directo de un sustrato de LiNbO3 encima de una guía PE diseñada a la frecuencia de corte y centrada en una región de dominio invertido de 10 micras de ancho y 10mm de largo. El dispositivo se ha caracterizado a baja frecuencia y ha sido posible medir campos eléctricos de hasta 2MV/m con un aumento de sensibilidad comparado con el primer dispositivo fabricado sin la técnica del bonding. Estos resultados muestran que los dispositivos desarrollados pueden ser utilizados para mediciones de campos eléctricos intensos en condiciones peligrosas sin ningún riesgo para el operador. Después de una breve introducción en el Capítulo 1 de esta Tesis, las propiedades del LiNbO3 se discuten en el Capítulo 2, prestando especial atención a sus características ópticas y electro-ópticas. El Capítulo 3 presenta las técnicas de micro fabricación desarrolladas durante este trabajo sobre sustratos de 3 pulgadas. En particular, se presentan las técnicas de fabricación de guías mediante intercambio protónico, de inversión de dominios mediante poling de alto voltaje, de bonding de LiNbO3 con diferentes sustratos (LiNbO3 , SiO2, Si) y la fabricación de capas delgadas. El Capítulo 4 ofrece una introducción sobre los moduladores interferométricos Mach-Zehnder de onda propagada, presentando sus principales características. Además se presenta una nueva estructura de modulador basada sobre inversión de dominios y los resultados obtenidos. El Capítulo 5 empieza con una introducción sobre los sensores de campo eléctrico y después se presentan dos nuevos sensores de campo eléctrico completamente ópticos fabricados en LiNbO3 z-cut. Los dispositivos están basados en las técnicas de intercambio protónico, inversión de dominios y bonding directo. Finalmente, en el Capítulo 6 se presentan las conclusiones y posibles desarrollos futuros que pueden contribuir al aumento del impacto de este trabajo en las industrias de comunicaciones ópticas y de detección.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.
Includes bibliographical references (leaves 84-90).
There is a great deal of interest and activity in the area of femtosecond micromachining of transparent materials. It promises to be a powerful technique for rapid fabrication of photonic devices in three dimensional geometries. Our group has fabricated and investigated an array of two dimensional and novel three dimensional photonic devices that are able to perform their intended functions but whose loss properties are not yet well known. The first aim of this Masters thesis is to study waveguide loss. It will focus on studying and characterizing the losses of straight and circularly curved waveguides - the building blocks of many practical devices. With a proper understanding of the loss per unit length, per unit bend angle, and per re-write of the waveguides a structured set of guidelines for device fabrication for our particular setup can be made. The second aim of this thesis is the characterization of the photonic devices fabricated and demonstrated by the author. These include a broadband characterization of directional and X couplers, as well as a demonstration of 3D symmetrical 1 :N waveguide splitters for optical signal distribution. These experimental results and discussions, which form the core of the thesis, flow in a logical fashion - from the elemental straight waveguides to the curved waveguides that are used to design the directional couplers. The X couplers provide the broadband performance that the directional couplers cannot and the 1 :N waveguide splitters fabricated with the aid of an improved experimental setup not only provide a more elegant re-design of the broadband X couplers but also demonstrate scalability to N output ports in three dimensions.
by Vikas Sharma.
S.M.

Au cours des dernières décennies, on a assisté à une croissance considérable dans le domaine des technologies des capteurs magnétiques. Le domaine est passé de simples dispositifs micro-usinés à base de silicium à des microsystèmes intégrés plus complexes combinant des transducteurs de haute performance ainsi que des interfaces sans fil. Cependant, presque tous ces appareils fonctionnent avec un mécanisme complexe tout en étant alimentés simultanément de l'extérieur et coûteux. Il y a donc un besoin profond de développer un capteur magnétique qui surmonte ces défis. Ces travaux de recherche ont porté sur le développement de capteurs à ondes élastiques de surface (SAW) pour la détection des champs magnétiques. La configuration résonateur a été considérée dans cette étude afin de permettre une interrogation sans fil. La première partie de notre travail est consacrée à l’étude de la physique et à l'interaction entre les ondes élastiques et les couches magnétostrictives lorsqu'elles sont soumises à un champ magnétique. Nous avons donc étudié des résonateurs SAW en utilisant le niobate de lithium comme substrat et un empilement multicouches [TbCo2/FeCo] comme électrode et matériau sensible. Nous avons étudié et montré le rôle de l'effet de forme dans le magnétisme résultant de la géométrie de l'électrode. Un banc de mesure expérimental a été mis au point pour démontrer l’utilisation d’un capteur magnétique SAW pour la mesure du courant électrique le long d’une lignes hautes tension. Par la suite, nous avons développé un capteur auto-compensé en température rendant sa fréquence de résonance uniquement sensible à l’intensité du champ magnétique. Ce capteur à structure multicouche utilise la coupe ST du quartz comme substrat avec comme direction de propagation des ondes X+90°C. Cette direction de la coupe ST présente un coefficient de température positif (TCF) qui a été compensé par le les couches de ZnO et du CoFeB qui présentent un TCF négatif. Enfin, en combinant nos connaissances sur les effets de forme magnétiques et sur le comportement des structure SAW multicouche pour développer un dispositif qui non seulement annule les effets de la température sur la fréquence de résonance mais également sur l'anisotropie magnétique. De plus, cette structure présente également la possibilité de réaliser un dispositif multisensoriel puisque dans le même dispositif, plusieurs modes sont générés. En plus du mode compensé en température qui permet de mesurer l’intensité du champ magnétique, un autre peu sensible au champ magnétique, permettra de mesurer la température de l’environnement de fonctionnement
The last few decades have seen tremendous growth in the area of magnetic sensor technologies. The field has grown from simple micro-machined silicon based devices to more complex integrated microsystems combining high performance transducers as well as wireless interfaces. However, almost all of these devices operate with a complex mechanism while simultaneously being externally powered as well as expensive. Thus, there arises a deep need to develop a magnetic sensor that overcomes the challenges. This research work focused on the development of surface acoustic wave (SAW) sensors for the detection of magnetic field. Owing to the possibility of wireless interrogation, SAW devices of the resonator configuration have been considered in this study. The first part of our work aims to address the physics and interaction between the acoustic waves and magnetostrictive layers when subjected to a magnetic field. We investigated SAW resonators using LiNbO3 as the substrate and multi-layered [TbCo2/FeCo] as the electrode and sensitive material. We studied and showed the role of the shape effect in magnetism arising from the electrode geometry. A model experimental set-up was developed to demonstrate an application of the fabricated device as a sensor for detection of current along a cable. Subsequently, we developed a device that is self-compensated for the effects of temperature on the resonance frequency. The multi-layered sensor was based on ST-cut Quartz as the substrate whose positive temperature coefficient of frequency (TCF) was compensated for by the negative TCF of ZnO and CoFeB. Finally, we combine our understandings of the shape effects in magnetism and the multi-layered TCF compensated SAW structure to develop a device that is not only compensated for the effects of temperature on the resonance frequency but also on the magnetic anisotropy. In addition, this structure also presents the possibility of a proof-of-concept multi-sensory device because along with the temperature compensated resonance peak, there exist other resonances which are highly sensitive to any change in the temperature while at the same time immune to magnetic field

This thesis has focused on three key areas of interest for femtosecond micromachining and inscription. The first area is micromachining where the work has focused on the ability to process highly repeatable, high precision machining with often extremely complex geometrical structures with little or no damage. High aspect ratio features have been demonstrated in transparent materials, metals and ceramics. Etch depth control was demonstrated especially in the work on phase mask fabrication. Practical chemical sensing and microfluidic devices were also fabricated to demonstrate the capability of the techniques developed during this work. The second area is femtosecond inscription. Here, the work has utilised the non-linear absorption mechanisms associated with femtosecond pulse-material interactions to create highly localised refractive index changes in transparent materials to create complex 3D structures. The techniques employed were then utilised in the fabrication of Phase masks and Optical Coherence Tomography (OCT) phantom calibration artefacts both of which show the potential to fill voids in the development of the fields. This especially the case for the OCT phantoms where there exists no previous artefacts of known shape, allowing for the initial specification of parameters associated with the quality of OCT machines that are being taken up across the world in industry and research. Finally the third area of focus was the combination of all of the techniques developed through work in planar samples to create a range of artefacts in optical fibres. The development of techniques and methods for compensating for the geometrical complexities associated with working with the cylindrical samples with varying refractive indices allowed for fundamental inscription parameters to be examined, structures for use as power monitors and polarisers with the optical fibres and finally the combination of femtosecond inscription and ablation techniques to create a magnetic field sensor with an optical fibre coated in Terfenol-D with directional capability. Through the development of understanding, practical techniques and equipment the work presented here demonstrates several novel pieces of research in the field of femtosecond micromachining and inscription that has provided a broad range of related fields with practical devices that were previously unavailable or that would take great cost and time to facilitate.

碩士
國立臺灣大學
應用力學研究所
94
This research aims at developing a general solution for calculating the capacitance of fringe field precisely. Capacitive sensing and electrostatic actuating devices are commonly used on microdevices. Therefore, determination of the capacitance is critical in the design to determine the performances of such devices. Accurate determination of capacitance is very challenging in virtue of the fringing field. The finite element method (FEM) is often used for calculating the capacitance as lacking precision analytical model. FEM has been implemented in various commercial MEMS simulation software such as ANSYS, COMSOL, CovnetorWare, and Intellisuite. However, FEM has the disadvantages of un-explicit physical meaning and requiring massive numerical calculations, and therefore is not easy to carry out the parametric study of capacitive devices. This research develops an analytical solution for calculating the three-dimensional fringe field capacitance of paralleled-plate-type capacitors, which is the commonest structure. The analytical solution is derived from the conformal mapping method and simplified by some approximate approaching techniques. The present analytical solution shows very high accuracy within one-percentage error comparing with the experimental results and the numerical simulation by ANSYS. By the present high precision analytical solution, one can easily evaluate the capacitance in few seconds by manual work.

碩士
逢甲大學
自動控制工程學系
87
Four sets of Wheatstone bridge type contact pressure microsensors have designed in a 6mm ×6.5mm ×0.5mm silicon die. The microsensors are compound membrane structures. The active sensor located wafer is bonded to the force transmission wafer directly by the anodic-bonding technique. The back-side contact design makes only the contact membrane exposed to the measurement environment that improves the sensor pollution problem and avoids the electrical damage problems. The stress and strain geometry distribution and the response linearity are analyzed by the finite-element method using the package software of I-DEAS. The best parameter to modify the microsensor sensitivity is the thickness of the sensing elements suspended structure. The maximum compressive stress depends inversely on the square of the diaphragm thickness. The optimal value of the contact mesa width is 120 μm. The sensitivity of the designed microsensors are 77.17μV/V/mmHg, it''s much better than the commercial pressure microsensors being used to the human pulse-diagnosis. The devices have less influence in sensitivity than the commercial microsensors after packaging. The sensitivity ratio between the developed microsensors and commercial pressure microsensors was about 9.5. The simulation results provide the device design constrains to the sensor structures and layouts. The microsensors are designed for the human pulse-diagnosis that can measure human blood pressure, blood flow, arterial diameter, and relative pulse-correlation signals in a measurement at the same time.

Advanced Micro Devices (AMD) is a Silicon Valley-born semiconductor company,that had its IPO in 1972. Despiteits rough past, in the most recent years,AMD has beenable togaincompetitive advantage in relation to its industry peers,as well asmarket sharedue to its continuous innovative products’ lines of EPYC and Ryzen processors, and Radeon graphics.Furthermore, recentlyestablished partnerships and launched products give the company good growth prospects, in the near future.For these reasons an Equity Research Report was conducted on AMD, in order to get to a fair value of the stock.AMD’s valuationin the reportwas assessed through the Discounted Cash Flow (DCF)method, considering various factors that could affect the company’s financial statement lineitems.Among those factors are the Average Selling Price of its products, Units Shipments, Gross Margin, investments in innovation (R&D), and several partnerships alongside with the company’s Market Share.A scenario analysison the effects of the tariffs, comingfrom the Trade War,was also conductedon AMD’s price.The price target arrived for December 31, 2020 was $52.75, leading to a BUYinvestment recommendation, considering normal market conditions.

碩士
大同大學
機械工程學系(所)
92
This thesis is aimed at fabrication of microfluidics, including microactuator and micromixer. Firstly, a semiconductor electro-thermal microactuator is manufacture with the semiconductor technology. The microactuator is able to produce actuation due to a bi-metal structure. Make use of existing equipment to manufacture and test the microactuator devices that it’s in order to reach the purpose which develop fabrication easy and drive low energy. Microactuator device have succeeded to manufacture and have actuation result at present. Secondly, a micromixer is manufacture with the PDMS technology. Then we designed several kinds of geometry micromixer to observe mixing result. Utilize this experiment to let us understand the fluid characteristic under microscale. Expect to design the simple structure and optimum mixing result of micromixer devices through obtains the fluid flow mechanism under microscale.

碩士
淡江大學
機械與機電工程學系
91
This research was proposed to study on flow characteristics and pressure measuring the through microchannels. Recently, a number of publication indicate that flow characteristics on microscale are different from the traditional theory. Thus, this research first studies the effect on flow characteristics by changing hydraulic diameter and surface roughness in the microtubes. The experimental results were compared with the predictions from the conventional flow theory. We found for microtubes with large diameter(647mμ), the experimental results are rough agreement with the conventional theory. As the decrease of the diameter, value and pressure gradients were increase but flow rate and Re range came smaller. Friction factor were also increase as the decrease of the diameter. Surface roughness increase will make gas in the water to precipitate, result the increase of pressure gradients and the decrease of flow rate. Most experiment studies on flow characteristics through microchannels only measure flow rate, inlet and outlet pressure, then used equation to compare with traditional theory. This research second measured the pressure in micochannels. The experiments used hot embossing to put PVDF film in the micochannels, measure actual pressure through every separation of micochannels. Use Filter, Amplifier and Oscilloscope to analyze the PVDF output information. The experimental results were also rough agreement with the conventional theory. The experimental results indicate that actual pressure was a non-linear function, and pressure gradient decrease with the distance from inlet of micochannels increase.