Academic literature 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.

Two types of micro-mechanical memory cells are introduced in this paper. The programmable parameters are the resonant frequency of a micro-mechanical bridge and the tip deflection of a micro-mechanical cantilever. For both cases, the actuation was done by laser pulses that locally heated the vanadium dioxide (VO2) thin film coating. Due to the hysteretic behavior of the mechanical properties of the VO2 film coating across the transition, a different “memory state” was programmed with every pulse. The memory state remained programmed after the pulse ended, as long as the sample was maintained at a specific temperature (programming temperature) by using a Peltier heater. The resetting of the mechanical memory cell was accomplished by driving the temperature to regions outside the hysteretic region.