La protéomique, c'est-à-dire l’étude de la structure tridimensionnelle des protéines codées par le génome et des modifications qu’elles subissent, sous l’influence de l’environnement, des maladies et des médicaments, suscite un grand intérêt pour la communauté scientifique. La compréhension des changements dans l’expression des protéines est un enjeu important car ils pourraient être utilisés comme un indicateur biologique pour la détection des maladies et l’évaluation des effets thérapeutiques d’un médicament. Mais à ce jour, peu d’entre elles ont été caractérisées, leur nombre considérable nécessitant des analyses plus rapides, par le développement de dispositifs compatibles avec l’automatisation et intégrant de nombreuses fonctions : les laboratoires sur puce (LOC). La spectrométrie de masse apparaît comme la technique d’analyse la plus puissante pour les recherches en protéomique. Elle repose sur l’ionisation d’un liquide émis par une source d’électronébulisation sous forme de fines gouttelettes recueillies par un spectromètre qui procède à l’identification des protéines présentes. Cependant, les sources actuelles souffrent de nombreux inconvénients: dimensions mal contrôlées, incompatibilité avec l'automatisation et les LOC. Dans ce contexte, les micro et nanotechnologies ont été mises en œuvre pour la fabrication en masse peu coûteuse de nouvelles sources miniaturisées en silicium, intégrables dans un LOC. Les caractérisations montrent qu’elles offrent une meilleure sensibilité et une étude approfondie de l’émission des gouttelettes est proposée afin de mieux contrôler l’électronébulisation en vue d’autres applications comme l’écriture directe par nanolithographie. / Proteomics, i.e. study of three-dimensional structure of proteins encoded by genome and their alterations under the influence of environment, diseases and drugs, is of great interest for the scientific community. Understanding of changes in proteins expression is an important challenge as they can be used as a biological indicator for illnesses and drug therapeutic effects estimation. But nowadays, only few of them have been characterized, their considerable number requiring faster analysis, with the development of devices compatible with automation and integrating numerous functions: lab on a chip (LOC). Mass spectrometry appears to be the most powerful tool for proteomics researches. It relies on ionisation of a liquid by an electrospray source emitting tiny droplets collected by a mass spectrometer which carries out proteins identification. However, usual sources suffer from numerous drawbacks: poor control of dimensions, incompatibility with automation and LOC. In this context, we have made use of micro and nanotechnologies for new low cost miniaturized silicon sources mass fabrication, integrable in LOC. Characterizations show that these sources are more sensitive and a thorough study of droplets emission is suggested in order to enhance electrospraying control with the aim of other applications as direct writing by nanolithography.

Thesis (M. Eng.)--University of Louisville, 2000. / Typescript (Xerox copy). Department of Electrical Computer Engineering. Vita. Includes bibliographical references (leaves 432-441).

Thesis (M.S.)--University of Louisville, 2004. / Department of Electrical Engineering. Vita. "May 2004." Includes bibliographical references (leaf 54).

The environment encountered by a single cell in vivo is a complex and dynamic system that is often simplified experimentally via ex vivo and in vitro methods. As our understanding of cell response in these basic environments grows, there is a corresponding need for techniques that modify traditional cell culture in ways that better mimic the complexities of in vivo systems. This dissertation examines how the three dimensional (3D) properties of a focused pulsed laser can be incorporated within existing techniques to dynamically manipulate these microenvironments in the presence of single cells. As a modification on existing microfluidic technology for chemically dosing cells, it is shown how a cost-effective microchip laser can be used to ablate microscopic pores in a thin, biocompatible polymer membrane. These pores serve as conduits for introducing dosing reagents in close proximity to cultured cells combining subcellular resolution with spatial and temporal control. Because reagent flow is physically separated from the cell-culture flow chamber by this polymer membrane, the geometry of the reagent flow cell can be altered to accommodate multiple reagents flowing in parallel with minimal mixing due to the laminar flow characteristics of microfluidic devices. By manipulating reagent flow, a single cell can be dosed at opposing ends by distinct reagents or by defined, stable gradients of a single reagent. Additionally, these dosing streams can be switched with subsecond temporal resolution or dynamically mixed to study potential synergistic or antagonistic effects. To define the physical environment surrounding small populations of cells, an existing platform for mask-directed multiphoton lithography is used to create biocompatible protein-based microstructures for studying cancer-cell migration and invasion in physically confined regions. In these studies, a variety of 3D shapes incorporating spatial gradients are examined with invasive cell types. Additionally, these methods have been modified to allow for in situ fabrication of gelatin microstructures with 3D resolution around suspended somatic cells by covalently binding a photosensitizing molecule to the protein prior to fabrication. The architecture of these microstructures is designed to provide a variety of 3D confinement scenarios with biological relevance. / text

The evaporation phenomenon of a liquid droplet was investigated by using microfabricated heaters. All 32 microheaters were designed to have the same resistance. Gold microheaters worked both as temperature indicators and as heaters. The first experiment was performed under a constant voltage mode to investigate the temperature and heat flux variation of the heated surface by the evaporating droplet. The second experiment was performed under constant temperature mode to investigate the spatial and temporal heat flux variation of the constant temperature heater surface by the evaporating droplet heater. Droplet evaporation was recorded with a CCD camera. Experimental data showed temperature and heat flux variations inside and outside of the droplet with respect to time and radial position from the center of the droplet by tomographic deconvolution.

The evaporation phenomenon of a liquid droplet was investigated by using microfabricated heaters. All 32 microheaters were designed to have the same resistance. Gold microheaters worked both as temperature indicators and as heaters. The first experiment was performed under a constant voltage mode to investigate the temperature and heat flux variation of the heated surface by the evaporating droplet. The second experiment was performed under constant temperature mode to investigate the spatial and temporal heat flux variation of the constant temperature heater surface by the evaporating droplet heater. Droplet evaporation was recorded with a CCD camera. Experimental data showed temperature and heat flux variations inside and outside of the droplet with respect to time and radial position from the center of the droplet by tomographic deconvolution.

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No description available.

This paper will discuss the design, fabrication, and testing of a Poly(dimethylsiloxane) (PDMS) microfluidic pump. PDMS is commonly described as a soft polymer with very appealing chemical and physical properties such as optical transparency, low permeability to water, elasticity, low electrical conductivity, and flexible surface chemistry. PDMS microfluidic device fabrication is done easily with the use of soft lithography and rapid prototyping. PDMS microfluidic devices make it easier to integrate components and interface devices with particular users, than using typically harder materials such as glass and silicon. Fabrication and design of single and multilayer PDMS microfluidic devices is much easier and straightforward than traditional methods. A novel design of a PDMS micropump with multiple vibrating membranes has been developed for application in drug delivery and molecule sorting. The PDMS micropump consists of three nozzle/diffuser elements with vibrating membranes, which are used to create pressure difference in the pump chamber. Preliminary analysis of the fluidic characteristics of the micropump was analyzed with ANSYS to investigate the transient responses of fluid velocity, pressure distributions, and flow rate during the operating cycle of the micropump. The design simulation results showed that the movement of the wall membranes combined with rectification behavior of three nozzle/diffuser elements can minimize back flow and improve net flow in one direction. To prove that the theoretical design is valid, the fabrication and testing process of the micropump has been carried out and completed. This paper will discuss in depth the design, fabrication, and testing of the PDMS micropump.

This thesis reports research activity on suspended graphene membranes. Scientific results in the form of peer-reviewed publications are presented, along with supporting information to provide context, detailed experimental procedures, and recommendations of future work. The four papers cover a wide variety of topics, but are linked by common experimental sample fabrication techniques. Understanding the mechanical properties of suspended graphene membranes is crucial to the development of graphene nano-electromechanical devices. In the first presented paper, PeakForce QNM (quantitative nanomechanical mapping) atomic force microscopy imaging was used to rapidly map the nanomechanical properties of a range of suspended graphene membranes. The force-displacement behaviour of monolayer graphene extracted from the peak force imaging map was found to be comparable to that taken using standard nanoindentation. By fitting to a simple elastic model, the two-dimensional elastic modulus was measured at around 350Nm-1, corresponding to a Young's modulus of around 1 TPa. The second paper examines the near-IR light-matter interaction for graphene integrated cavity ring resonators based on silicon-on-insulator (SOI) racetrack waveguides. Fitting of the cavity resonances from the predicted transmission spectra reveal the real part of the effective refractive index for graphene, neff = 2.23 ± 0.02 and linear absorption coefficient, alphagTE = 0.11 ±0.01dB micro metre-1. The evanescent nature of the guided mode coupling to graphene at resonance depends strongly on the height of the graphene above the cavity, which places limits on the cavity length for optical sensing applications. Twisted-bilayer graphene (tBLG) exhibits van Hove singularities in the density of states that can be tuned by changing the twisting angle θ. In the third paper, θ-defined tBLG was produced and characterized using optical reflectivity and resonance Raman scattering. This represents the first reported fabrication of a rationally designed (twist engineered) tBLG structure. The θ-engineered optical response is shown to be consistent with persistent saddlepoint excitons. Separate resonances with Stokes and anti-Stokes Raman scattering components can be achieved due to the sharpness of the two-dimensional saddle-point excitons, similar to what has been previously observed for one-dimensional carbon nanotubes. The excitation power dependence for the Stokes and anti-Stokes emissions indicate that the two processes are correlated and that they share the same phonon. Nano-patterned and suspended graphene membranes find applications in electronic devices, filtration and nano-pore DNA sequencing. However, the fabrication of suspended graphene structures with nanoscale features is challenging. In the fourth and final paper, the direct patterning of suspended membranes consisting of a graphene layer on top of a thin layer of hexagonal boron nitride which acts as a mechanical support is demonstrated for the first time, using a highly focused electron beam to fabricate structures with extremely high resolution within the scanning transmission electron microscope. The boron nitride support enables the fabrication of stable graphene geometries which would otherwise be unachievable, by preventing intrinsic strain in graphene membranes from distorting the patterned features after areas are mechanically separated. Line cuts with widths below 2 nm are reported. It is also demonstrated that the cutting can be monitored in-situ utilising electron energy loss spectroscopy (EELS).