Microfluidic technology is a useful tool to help answer unsolved problems in multidisciplinary fields, including molecular biology, clinical pathology and the pharmaceutical industry.Current microfluidic based devices with diverse structures have been constructed via extensively used soft lithography orphotolithography fabrication methods. A layer-by-layer stacking of 2D planar microchannel arrays can achieve limited degrees of three dimensionality. However, assembly of large-scale multi-tiered structures is tedious, and the inherently planar nature of the individual layers restricts the network’s topological complexity. In order to overcome the limitations of existing microfabrication methodswe demonstrate several novel methods that enable microvasculature networks: electrostatic discharge,global channel deformation and enzymatic sculpting to fabricate complex surface topologies. These methods enable construction of networks of branched microchannels arranged in a tree-like architecture with diameters ranging from approximately 10 μm to 1 mm. Interconnected networks with multiple fluidic access points can be straightforwardly constructed, and quantification of their branching characteristics reveals remarkable similarity to naturally occurring vasculature. In addition, by harnessing enzymatic micromachining we are able to construct nanochannels, microchannels containing embedded features templated by the substrate’s crystalline morphology, and an irregular cross section of microchannel capable of performing isolation and enrichment of cells from whole blood with throughput 1 – 2 orders of magnitude faster than currently possible. These techniques can play a key role in developing an organ-sized engineered tissue scaffolds and high-throughput continuous flow separations.

This diploma thesis deals with the investigation of the metal-assisted catalytic etching (MaCE) of Si. One of the main goals is to study fabrication of stamps for nanoimprint lithography using MaCE. Formation of nanoporous silicon (PSi), Si nanowires (SiNWs) and three-dimensional nanostructures in Si by MaCE is demonstrated. For this purpose optical lithography, electron beam lithography (EBL), shadow mask evaporation and aerosol nanoparticles deposition techniques have been utilized. The etching rate and surface morphology of Si (with Au lift-off films as a catalyst) as functions of time and concentrations of chemicals are measured in the current diploma work using optical microscope and scanning electron microscopy (SEM). In the current thesis it is shown that Si structures with sub-150 nm lateral sizes, high aspect ratio (up to 1:21), well-defined shapes, and various complexity can easily be fabricated by means of MaCE process.

The introduction of deep reactive ion etching (DRIE) technology has greatly expanded the accessible design space for microscopic systems. Structures that are hundreds of micrometers tall with aspect ratios of 40:1, heretofore impossible, can now be achieved. However, this technology is primarily a forming technology, sculpting structures from a substrate. This work seeks to complement deep reactive ion etching by developing an electrical isolation technology to enable electro-mechanical function in these new deep reactive ion etched structures. The objective of the research is twofold. The first is to develop and characterize an electrical isolation technology for DRIE, single crystal silicon (SCS) micro-electro-mechanical systems (MEMS) using temperature gradient zone melting (TGZM) of aluminum junctions for diodic isolation. The second is to demonstrate the utility of this electrical isolation technology in the design, simulation, fabrication, and testing of a MEMS device, i.e. a micro-gyroscope, in such a way that the benefits from junction isolated, deep reactive ion etched, single crystal silicon devices are preserved.

Abstract The high-speed performance of the lump-type electroabsorption modulator (EAM) is mainly limited by RC-effect. By taking advantage of the distributive effects, the traveling-wave structure can overcome the RC-lump effect. However, in order to enhance the limitation imposed by the conventional slow-waveguide type of traveling-wave structure, the speed of the device is still mainly restricted by the distributed capacitance of the waveguide. In this work, a novel type of traveling-wave-electroabsorption-modulator based on the undercut-etching the active region is successfully fabricated and measured. The methods of the processing adopted here is to lower the capacitance by chemical-wet-etching and two-time subsequent undercut etching on active region to further decrease the parasitic capacitance between P-type and N-type cladding layer. Also, the optical scattering loss may be reduced due the smooth sidewall of the waveguide from the wet etching. The whole processing shown in this thesis includes the lift-off technique by lithography, the metalization for n-, p- contacts (by thermal evaporator) and CPW microwave transmission (by e-beam evaporator), and PMGI-planarization. ¡V15dB optical transmission, ¡V6dB electrical transmission loss and >20GHz 3dB bandwidth of electrical-to-optical response at 50£[termination is measured on this kind of devices. It exhibits a high potential on the application of high-speed optical-fiber link in the future.

In this thesis, we study high quality InN films grown on sapphire (0001) by plasma-assisted molecular beam epitaxy (PAMBE). We used double layers methods to reduce lattice mismatch successfully. In this experiment, we have two series of samples, about series of A use low temperature GaN (LT-GaN) as the buffer layer as compared with series of B use high temperature AlN (HT-AlN) as the buffer layer. By in situ reflection high-energy electron diffraction (RHEED), we got film¡¦s surface situation. Surface morphology of the samples was observed by atomic force microscope (AFM). By high resolution X-ray diffraction (HR-XRD) methods was analyzed quality and composition of InN films. Van der Pauw method (Hall) was used to determine carrier concentration and mobility. The optical properties of InN films under different growth conditions were investigated by photoluminescence (PL). By changing growth temperature of these samples, we found the series of A having some fine characters as the InN(0002) rocking curve was 343 arcsec and InN(10-12) rocking curve was nearly 1000 arcsec. The mobility and carrier density of these samples were approximately 1000 cm2/Vs and 3 x 1018 cm-3 by Van der Pauw method.

In this work, a novel type of optical waveguide, namely two-step undercut-etching Si waveguide (TSUESW), fabricated in Si-substrate is proposed and demonstrated. All this waveguide processing is based on two step of SF6-based dry etching method. In the first step, an anisotropic etching by Reactive Ion Etching (RIE) is used to define the waveguide core. After that, an undercut etching through an isotropic etching processing Electron Cyclotron Resonance (ECR) is then utilized to decouple the optical light of the waveguide core from Si substrate. In the measurement setup, an optical propagation loss coefficient of 2.89dB/cm is obtained by extracting from Fabry-Perot oscillation, suggesting the confined optical mode in TSUESW can be realized. A tapered optical waveguide is also designed and fabricated, where the core of tapered structure is defined as widths of from 20£gm to 6£gm for optical fiber coupler. A 4.13dB/cm of loss from 700£gm long waveguide is found in such tapered waveguide. Through the nonlinear properties of Si material, a Four-Wave Mixing (FWM) behavior is observed in tapered waveguide, further confirming the optical power can be highly confined in small core of TSUESW. It also should be noted that the waveguide technology template can be processed in a Si-substrate to realize CMOS-compatible processing, avoiding high-cost Silicon-On-Insulator (SOI) technology.

The vitality of the human figure has been an unending source of curiosity for artists from the beginning to now. Although many artists have focused their creativity to searching for the perfect, in fact, beautiful, human form, others have striven to convey the human experience within the spirit of their own era. The latter is true of this creative project, which has addressed the following problem: hog: could large-scale intaglio printmaking be used to 02arify the negative impact our rigid contemporary notion of beauty can have on individual women? The project was inspired by the work of Kaethe Kollwitz, German artist of the early 20th century whc used her technical drawing skills to translate her knowledge of war and famine shattered women into forceful lithographs and etchings. The insight she Portrayed vividly combined her intensely personal vision the Vicious events of her times: social commentary at its finest.The significance of the project has been, first of all, its benefit to myself, the artist. The journey which I undertook through historical research on Kollwitz; conceptual investigation of women and rigid norms for beauty; and extension of my technical expertise as an etcher-has produced insights about creating art that are invaluable to the mature artist. The second significance involves the viewer, whom I hope reconsiders the images of women displayed in contemporary society.The project’s five large-scale etchings of the female figure portray in a series my ideas about roles women are expected to assume in contemporary American society. These ideas unfolded especially during the creation of the first and second etchings.The report of the project deals extensively with the drawing and etching techniques used for each print; a description of each of the works; the ideas which inspired the content of the works; how these ideas were transformed into visual images; and the technical competencies that I acquired while working through each plate. / Department of Art

Highly fluid repellent have application in many industries ranging from marine to biomedical due to their self-cleaning antifouling properties. The development and implementation of these superhydrophobic (water contact angle >150 degrees ) and superoleophobic (oil contact angle > 150 degrees ) surfaces were studied in this thesis. We focused our studies on paper as a substrate for these superhydrophobic and superoleophobic surfaces. Cellulose based paper is a biodegradable, inexpensive material that is ideal for disposable use applications. Applying an oxygen plasma etching technique combined with the deposition of a fluoropolymer from a pentafluoroethane precursor, superhydrophobic paper can be attained. This superhydrophobic paper is functionalized by printing wax islands onto the surface, thereby creating areas of high fluid adhesion. These wax functionalized sheets are used to sample droplets from bulk droplets, with the sampled volume being controlled by the hysteresis of the wax island. Disposable biomedical devices can be envisioned from these wax designs. While these superhydrophobic surface excel at repelling water, they continue to readily absorb water. Formation of paper that is both superhydrophobic and superoleophobic, or superamphiphobic, is accomplished through a combination of steps: mechanical fiber refining, solvent exchange processing and plasma treatment. The fiber refining creates nano-scale fibrils that are separated in the solvent processing. Subsequent plasma treatment of oxygen etching and fluoropolymer deposition creates superamphiphobic paper, exhibiting contact angles of > 150 degrees for water, ethylene glycol, motor oil and n-hexadecane. Further studies were conducted to increase the strength of these superamphiphobic sheets by using layered paper. Development of superhydrophobic paper from a hydrophilic diamond-like carbon surface coating was also demonstrated. When combined with oxygen plasma etching, diamond-like carbon coated paper sheets attain superhydrophobic properties similar to fluoropolymer coated sheets. Based on the knowledge gained from the studies on paper, superhydrophobic surfaces are created on 304 and 316 stainless steels. Samples are etched in hydrofluoric acid and then passivated in nitric acid to create the necessary surface structure. Deposition of fluoropolymer onto the etched samples yields superhydrophobic properties.

Thesis (B.S.)--Rochester Institute of Technology, 1986. / Typescript. Includes bibliographical references (leaf 34).

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 169-171). Available also in a digital version from Dissertation Abstracts.