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1
Feng, Chunhua. "Microfabrication-compatible synthesis strategies for nanoscale electrocatalysts in microfabricated fuel cell applications /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CENG%202007%20FENG.
Повний текст джерела
2
Cannon, Andrew Hampton. "Unconventional Microfabrication Using Polymers." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/19845.
Повний текст джерелаАнотація:
Current microfabrication materials include silicon, a wide variety of metals, dielectrics, and some polymers. Because of the low cost and high processing flexibility that polymers generally have, expanding the use of polymers in microfabrication would benefit the microfabrication community, enabling new routes towards goals such as low-cost 3D microfabrication.
This work describes two main unconventional uses of polymers in microfabrication. The first unconventional use is as a carrier material in the self-assembly (SA) of millimeter-scale parts in which functional electronic components and electrical interconnects were cast into 5 mm cubes of Polymethylmethacrylate (PMMA). The second unconventional use is as a non-flat micromold for an alumina ceramic and as transfer material for multiple layers of micropatterned carbon nanotubes (CNTs). Both of these uses demonstrate 3D low-cost microfabrication routes.
In the SA chapter, surface forces induced both gross and fine alignment of the PMMA cubes. The cubes were bonded using low-melting temperature solder, resulting in a self-assembled 3D circuit of LEDs and capacitors. The PMMA-encasulated parts were immersed in methyl methacrylate (MMA) to dissolve the PMMA, showing the possibility of using MEMS devices with moving parts such as mechanical actuators or resonators. This technique could be expanded for assembly of systems having more than 104 components. The ultimate goal is to combine a large number of diverse active components to allow the manufacture of systems having dense integrated functionality.
The ceramic micromolding chapter explores micromolding fabrication of alumina ceramic microstructures on flat and curved surfaces, transfer of carbon nanotube (CNT) micropatterns into the ceramic, and oxidation inhibition of these CNTs through ceramic encapsulation. Microstructured master mold templates were fabricated from etched silicon, embossed thermally sacrificial polymer, and flexible polydimethylsiloxane (PDMS). The polymer templates were themselves made from silicon masters. Thus, once the master is produced, no further access to a microfabrication facility is required. Using the flexible PDMS molds, ceramic structures with mm-scale curvature were fabricated having microstructures on either the inside or outside of the curved macrostructure. It was possible to embed CNTs into the ceramic microstructures. To do this, micropatterned CNTs on silicon were transferred to ceramic via vacuum molding. Multilayered micropatterned CNT-ceramic devices were fabricated, and CNT electrical traces were encapsulated with ceramic to inhibit oxidation. During oxidation trials, encapsulated CNT traces showed an increase in resistance that was 62% less than those that were not encapsulated.
3
Barham, Oliver M. "Microfabricated Bulk Piezoelectric Transformers." Thesis, University of Maryland, College Park, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10615552.
Повний текст джерелаАнотація:
Piezoelectric voltage transformers (PTs) can be used to transform an input voltage into a different, required output voltage needed in electronic and electro- mechanical systems, among other varied uses. On the macro scale, they have been commercialized in electronics powering consumer laptop liquid crystal displays, and compete with an older, more prevalent technology, inductive electromagnetic volt- age transformers (EMTs). The present work investigates PTs on smaller size scales that are currently in the academic research sphere, with an eye towards applications including micro-robotics and other small-scale electronic and electromechanical sys- tems. PTs and EMTs are compared on the basis of power and energy density, with PTs trending towards higher values of power and energy density, comparatively, indicating their suitability for small-scale systems. Among PT topologies, bulk disc-type PTs, operating in their fundamental radial extension mode, and free-free beam PTs, operating in their fundamental length extensional mode, are good can- didates for microfabrication and are considered here. Analytical modeling based on the Extended Hamilton Method is used to predict device performance and integrate mechanical tethering as a boundary condition. This model differs from previous PT models in that the electric enthalpy is used to derive constituent equations of motion with Hamilton’s Method, and therefore this approach is also more generally applica- ble to other piezoelectric systems outside of the present work. Prototype devices are microfabricated using a two mask process consisting of traditional photolithography combined with micropowder blasting, and are tested with various output electri- cal loads. 4mm diameter tethered disc PTs on the order of .002cm
3 , two orders smaller than the bulk PT literature, had the followingperformance: a prototype with electrode area ratio (input area / output area) = 1 had peak gain of 2.3 (± 0.1), efficiency of 33 (± 0.1)% and output power density of 51.3 (± 4.0)W cm
-3 (for output power of80 (± 6)mW) at 1M? load, for an input voltage range of 3V-6V (± one standard deviation). The gain results are similar to those of several much larger bulk devices in the literature, but the efficiencies of the present devices are lower. Rectangular topology, free-free beam devices were also microfabricated across 3 or- ders of scale by volume, with the smallest device on the order of .00002cm
3 . These devices exhibited higher quality factorsand efficiencies, in some cases, compared to circular devices, but lower peak gain (by roughly 1/2 ). Limitations of the microfab- rication process are determined, and future work is proposed. Overall, the devices fabricated in the present work show promise for integration into small-scale engi- neered systems, but improvements can be made in efficiency, and potentially voltage gain, depending on the application
4
Mehregany, Mehran. "Microfabricated silicon electric mechanisms." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/14042.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1990.Includes bibliographical references (leaves 151-156).
by Mehran Mehregany.
Ph.D.
5
Florian, Baron Camilo. "Laser direct-writing for microfabrication." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/400403.
Повний текст джерелаАнотація:
Digital manufacturing constitutes a real industrial revolution that is transforming the production processes from the early stages of research and development to mass production and marketing. The biggest difference in comparison with old fabrication methods is the possibility to perform changes in the pattern design just by using mouse clicks instead of modifying an already fabricated prototype, which results in faster, cheaper and more efficient fabrication processes. For example, new technologies enabling the production of printed electronic devices on flexible substrates and compatible with roll-to-roll processing methods would result in cheaper fabrication costs than the traditional batch processing of silicon wafers. Such fabrication methods comprise a series of processing steps which are applied to the substrates while they are moving on rolls in the fabrication line. Therefore, it is desired that the new technologies can work at high speeds allowing at the same time the production of miniaturized features.
Lasers are a versatile tool that can meet the demands of flexibility, speed, resolution and compatibility with roll-to-roll processing of digital manufacturing. The main advantages of laser radiation rely in its unique properties: high directionality, coherence and monochromaticity. The combination of such properties allows generating high intensities that can be focused into extremely small volumes, which makes lasers an ideal tool for the processing of materials at the micro- and nano-scale, not only as a subtractive but also as an additive technique.
Laser ablation is the best known subtractive technique and it consists in the irradiation of a material with a focused laser beam. In the case of working with transparent materials, surface ablation constitutes a serious challenge since it is necessary to develop new strategies that allow controlling the position where the energy is delivered to ensure that ablation really occurs in the surface without modifying the bulk material. On the other hand, lasers can also be used as additive tools. For example, laser-induced forward transfer (LIFT) allows the transfer of materials in both solid and liquid state with high spatial resolution. In spite of the extensive amount of research on LIFT, some challenges still remain. For instance, the understanding of the particular printing dynamics encountered during the high speed printing of liquids, or the problem of printing uniform, continuous and stable lines with high spatial resolution.
The objective of this thesis is to propose and implement feasible solutions to some of the challenges that are associated with both the subtractive and additive laser based techniques presented above. On one side, we study the laser ablation of transparent polymers using femtosecond laser pulses with the aim of achieving spatial resolutions that overcome the diffraction limit, and at the same time solving the problem of the required precise focusing of the laser beam on the materials surface. On the other side, we study the LIFT transfer dynamics during the high speed printing of liquids, and we propose alternative printing strategies to solve the inherent quality defects usually encountered during the formation of printed lines. Finally, two different approaches that are a combination of both subtractive and additive techniques are presented; we implement LIFT for the fabrication of liquid microlenses used for the surface nanopatterning of materials, and on the other side, we create fluidic guides by laser ablation for the printing of high quality continuous lines.La fabricació digital de dispositius tecnològics requereix el desenvolupament de noves i millors tècniques per al microprocessament de materials que al mateix temps siguin compatibles amb mètodes de producció en sèrie a gran escala com el roll-to-roll processing. Aquestes tècniques han de complir certs requisits relacionats amb la possibilitat de realitzar canvis de disseny ràpids durant el procés de fabricació, alta velocitat de processament, i al mateix temps permetre la producció de motius de forma controlada amb altes resolucions espacials. En la present tesi es proposen i implementen solucions viables a alguns dels reptes presents a la microfabricació amb làser tant substractiva com additiva. D'una banda, es presenta un nou mètode d'enfocament del feix làser sobre la mostra per l'ablació superficial de materials transparents que permet obtenir resolucions espacials que superen el límit de difracció del dispositiu òptic. D'altra banda, es duu a terme un estudi de la dinàmica de la impressió de líquids mitjançant làser a alta velocitat, de gran interès de cara a la implementació industrial de la tècnica. A més, es presenten estratègies d'impressió de tintes conductores amb l'objectiu de produir línies contínues amb alta qualitat d'impressió. Finalment s'inclouen dues propostes que són producte de la combinació d’ambues tècniques, la impressió de líquids i l'ablació amb làser.
6
Jeffery, Nicholas Toby. "PET radiochemistry on microfabricated devices." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420892.
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7
Velásquez, García Luis Fernando 1976. "A microfabricated colloid thruster array." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/82201.
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8
Lubratt, Mark Paul. "A voltage-tunable microfabricated accelerometer." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/37497.
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9
Harris, Robert Michael. "Geometric simulation of microfabricated structures." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11842.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (p. 295-302).
Robert Michael Harris.
Ph.D.
10
Wang, Weihua. "Tools for flexible electrochemical microfabrication /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/9854.
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11
Guan, Jingjiao. "Microfabricated particulate devices for drug delivery." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1118247862.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xxiii, 163 p.; also includes graphics. Includes bibliographical references (p. 118-123). Available online via OhioLINK's ETD Center
12
McAllister, Devin Vincent. "Microfabricated needles for transdermal drug delivery." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/11031.
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13
Henry, Sʹebastien. "Microfabricated device for transdermal drug delivery." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/20707.
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14
Griffith, Alun Wyn. "Applications of microfabrication in biosensor technology." Thesis, University of Glasgow, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361768.
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15
Steyn, J. Lodewyk (Jasper Lodewyk) 1976. "A microfabricated ElectroQuasiStatic induction turbine-generator." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32463.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2005.Includes bibliographical references (p. [263]-268).
An ElectroQuasiStatic (EQS) induction machine has been fabricated and has generated net electric power. A maximum power output of 192 [mu]W at 235 krpm has been measured under driven excitation of the six phases. Self excited operation was also demonstrated. Under self-excitation, no external drive electronics are required and sufficient power was produced to dimly light four LED's on two of the six phases. This is believed to be the first demonstration of both power generation and self-excited operation of an EQS induction machine of any scale reported in the open literature. The generator comprises 5 silicon layers, fusion bonded together, and annealed at 700⁰C. The turbine rotor, 4 mm in diameter, is supported on gas bearings. The thrust bearings are formed by a shallow etch of 1.5 [mu]m to define the thrust bearing gap. Thrust bearing pressurization is through 10 [mu]m diameter nozzles, etched 100 [mu]m deep. The journal bearing is a precision, ... wide, 300 [mu]m deep annular trench around the periphery of the turbine disk. The generator airgap is 3 [mu]m. The inner radius of the generator is 1.011 mm, and the outer radius 1.87mm. The machine has ].31 poles for each of the 6 phases, for a total of 786 stator electrodes. Precise microfabrication and aligned, full-wafer fusion bonding enabled turbine generator devices to be operated at rotational speeds as high as 850 krpm. A detailed state-space model of the EQS machine and its external parasitics is presented. The external stray capacitances, and their unbalance, play a critical role in the performance of the device. A method for estimating the strays experimentally is discussed.
(cont.) This estimated, updated model made it possible to use computer optimization techniques to find the optimal drive conditions for the device to generate maximum power. Carrier depletion in the moderately doped polysilicon rotor conductor film prevented the generator from producing power at higher voltages, and limited the maximum machine terminal voltage under self-excitation to approximately 30 Vp-p.
by Jasper Lodewyk Steyn.
Ph.D.
16
Muller, Rikky 1980. "A microfabricated dielectrophoretic micro-organism concentrator." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28393.
Повний текст джерелаАнотація:
Thesis (M. Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 2004."May 2004."
Includes bibliographical references (leaves 83-85).
This project focuses on the development of a micro-organism concentrator. Pathogen detection, particularly MEMS based detection, is often limited by sample concentration. The proposed concentrator will interface with a pathogen detector. This type of pathogen concentrator can be useful for many kinds of applications including water purification systems, medical applications and biological warfare agent detection. Due to the nature of these applications, the concentrator must be able to operate under real-world conditions, and be robust to particulates and variations in solution conductivity. The concentrator is an active filter, which concentrate bacteria in solution using negative dielectrophoresis, which pushes objects away from the electrodes toward field minima. An electric field barrier is set up to guide cells toward a concentrated outlet flow path while the bulk of the fluid, which permeates the electric field barrier, is sent to a waste outlet. The cells are collected at the outlet and selectively released by turning off the applied voltage. I have fully designed and modeled the characteristics of the proposed concentrator and successfully fabricated the design. I have characterized the system throughput using polystyrene beads and I have characterized the system electrically using lumped circuit element models.
by Rikky Muller.
M.Eng.and S.B.
17
Srinivasan, Ravi 1971. "Microfabricated reactors for partial oxidation reactions." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9865.
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18
Mehta, Ankur 1983. "A microfabricated solid oxide fuel cell." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/27050.
Повний текст джерелаАнотація:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science; and, (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2004.Includes bibliographical references (p. 83-85).
With the ever-increasing ubiquity of mobile consumer electronic devices comes the rising demand for portable electric power. Current battery technology gives a very modest energy return per weight or volume. Hydrocarbons have a significantly higher energy density, and so fuel conversion systems only need to have several percent efficiency to match and surpass the specific energy of conventional batteries. Thus, there is a strong market for successful portable fuel powered electric generators. The goal of this thesis is to investigate the design of one such device, a two-chamber microfabricated solid oxide fuel cell (SOFC). This device produces electric current through the electrochemical oxidation of fuel through an ionic conductor. Oxide ions permeate across a ceramic electrolyte membrane to react with the fuel, driving electrons back around through the load. The focus of this work is to analyze the behavior of these membranes to prevent failure as the device is heated to its operating temperature near 800K. Experiments and analysis of free-standing electrolyte membranes indicate that failure is unavoidable over the required temperature range, and so supported structures are investigated. The results of experiments with a perforated nitride supported membrane presented herein indicate the need for a more thorough understanding of the thin film stresses responsible for membrane failure, as well as careful support structures to accommodate these. Designs for future devices are presented to improve stability and move closer to a final complete portable power system.
by Ankur Mehta.
S.B.
M.Eng.
19
Hsing, I.-Ming 1968. "Simulation strategies for microfabricated chemical systems." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/10061.
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20
Lin, Chia-Hua. "A Microfabricated Deep Brain Stimulation Electrode." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1244061398.
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21
Gao, Yuanfang. "Microfabricated devices for single cell analysis." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4429.
Повний текст джерелаАнотація:
Thesis (Ph.D.)--University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on May 1, 2009) Vita. Includes bibliographical references.
22
Massin, Charles. "Microfabricated planar coils in nuclear magnetic resonance /." [S.l.] : [s.n.], 2004. http://library.epfl.ch/theses/?nr=2913.
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23
Moore, Christopher Wayne. "Microfabricated Fuel Cells To Power Integrated Circuits." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7106.
Повний текст джерелаАнотація:
Microfabricated fuel cells have been designed and constructed on silicon integrated circuit wafers using many processes common in integrated circuit fabrication, including sputtering, polymer spin coating, reactive ion etching, and photolithography. Fuel delivery microchannels were made through the use of sacrificial polymers. The characteristics of different sacrificial polymers were studied to find the most suitable for this work. A polypropylene carbonate solution containing a photo-acid generator could be directly patterned with ultraviolet exposure and thermal decomposition. The material that would serve as the fuel cells proton exchange membrane (PEM) encapsulated the microchannels. Silicon dioxide deposited by plasma enhanced chemical vapor deposition (PECVD) at relatively low temperatures exhibited material properties that made it suitable as a thin-film PEM in these devices. By adding phosphorous to the silicon dioxide recipe during deposition, a phosphosilicate glass was formed that had an increased ionic conductivity. Various polymers were tested for use as the PEM or in combination with oxide to form a composite PEM. While it did not work well alone, using Nafion on top of the glass layer to form a dual-layer PEM greatly enhanced the fuel cell performance, including yield and long-term reliability. Platinum and platinum/ruthenium catalyst layers were sputter deposited. Experiments were performed to find a range of thicknesses that resulted in porous layers allowing contact between reactants, catalyst, and the PEM. When using the deposited glasses, multiple layers of catalyst could be deposited between thin layers of the electrolyte, resulting in higher catalyst loading while maintaining porosity. The current and power output were greatly improved with these additional catalyst layers.
24
Duan, Xuefeng 1981. "Microfabrication : using bulk wet etching with TMAH." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97942.
Повний текст джерелаАнотація:
In November 2002 a Microfabrication Lab was established in the physics department of McGill University to support research in nanoscience and technology. At the same time, I arrived at McGill to begin my graduate study. So I was assigned to do research on microfabrication, especially bulk wet etching of silicon using TetraMethyl Ammonium Hydroxide (TMAH).The content of microfabrication is quite broad, and also very useful in both industry and academic. Since our fab is a newly built one and I had no experience in this area before, this thesis mainly included some basic processes in microfabrication, such as the photolithography, wet etching, reactive ion etching, and soon. Also it compared the wet etching with dry etching. Some results of TMAH wet etching were showed in the thesis, which agreed well with that of the other groups. A simulation program was developed to predict the etching result of TMAH and it appeared to work well. Finally, based on the knowledge and experience acquired, processes in making cantilever and tip structures, which are critical in the scanning probe microscopes, were developed. Silicon oxide cantilevers with length of 100-200 mum, width of 30-50 mum, and thickness of 1 mum were obtained. Pyramid like silicon tips were also fabricated using the wet etching.
25
DiBartolomeo, Franklin. "HIGH SPEED CONTINUOUS THERMAL CURING MICROFABRICATION SYSTEM." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_theses/105.
Повний текст джерелаАнотація:
Rapid creation of devices with microscale features is a vital step in the commercialization of a wide variety of technologies, such as microfluidics, fuel cells and self-healing materials. The current standard for creating many of these microstructured devices utilizes the inexpensive, flexible material poly-dimethylsiloxane (PDMS) to replicate microstructured molds. This process is inexpensive and fast for small batches of devices, but lacks scalability and the ability to produce large surface-area materials. The novel fabrication process presented in this paper uses a cylindrical mold with microscale surface patterns to cure liquid PDMS prepolymer into continuous microstructured films. Results show that this process can create continuous sheets of micropatterned devices at a rate of 1.9 in2/sec (~1200 mm2/sec), almost an order of magnitude faster than soft lithography, while still retaining submicron patterning accuracy.
26
Charlton, Martin David Brian. "Computational design and microfabrication of photonic crystals." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287304.
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27
Zoorob, Majd Elias. "Computational design and microfabrication of photonic quasicrystals." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342813.
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28
Shirley, Timothy Earl. "Frequency-pulling effects in microfabricated resonant structures." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12344.
Повний текст джерелаАнотація:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1993.Includes bibliographical references (leaves 138-139).
by Timothy Earl Shirley.
M.S.
29
Diez, Shana 1980. "Preliminary performance characteristics of a microfabricated turbopump." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/32241.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2003.Includes bibliographical references (p. 175-176).
The demonstration micro turbopump was designed to prove the feasibility of pumping a liquid using a turbopump on the micro scale. This thesis presents the first data indicating positive pumping from the demonstration micro turbopump. Data pertaining to both the turbomachinery as well as the bearing systems for these preliminary tests is shown and discussed. The pressure rise through the pump, turbine pressure ratio, respective powers, and a system efficiency are presented. Bearing theory and static flow test data are discussed. The pump design is detailed. Modelling data is presented to help describe the operational difficulties with the highly coupled aft bearing system. These operational difficulties lead to the redesign of the aft bearing system, which is described in detail. Other operational procedures developed and discussed include the pump start up procedure and the use of the inverted journal bearing.
by Shana Diez.
S.M.
30
Shur, Maiya 1980. "Microfabrication methods for the study of chemotaxis." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/27130.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (leaves 59-60).
We have developed a system for studying chemotaxis in a microfabricated system. The goal was to develop a system capable of generating spatially and temporally stable concentration gradients of a chemotactic molecule while providing a viable environment for the cell. Numerical models were generated to investigate fluid flow in microchannels for given geometries. Through computational modeling and experimentally-driven iteration of the design, features of the chamber were determined and geometry was established. Prototypes of the system were fabricated using soft lithography and multi-layer soft lithography techniques. Three fluid delivery methods for establishing gradients in the system have been studied: gravity feed system, dual-syringe pump feed system, and integrated individually-controlled peristaltic pump feed system. We were able to create spatially and temporally stable gradients using the dual-syringe feed setup. Two syringes were used to pump a chemokine and a buffer in parallel channels that are connected by a cross-channel and terminated to a single output. Microbeads in the flow were used to confirm the lack of movement in the cross-channel. Human neutrophil viability over the course of several hours and directed cell movement was demonstrated in microchannels.
by Maiya Shur.
S.M.
31
Voldman, Joel. "A microfabricated liquid mixer for biomedical applications." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10461.
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32
Protz, Christopher S. (Christopher Stephen) 1977. "Experimental investigation of microfabricated bipropellant rocket engines." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/17794.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004.MIT Institute Archives copy: p. 301-328 bound in reverse order.
Includes bibliographical references (p. 325-328).
As satellite missions begin to require smaller satellites, launch systems and attitude control thrusters of reduced mass will be required. Microrocket engines could provide a low mass, high specific impulse, modular answer to these needs. These small rocket engines would produce thrust of order of 10's of Newtons at a thrust-to-weight of over 1000, over 10 times the thrust-to-weight of conventional chemical liquid bipropellant engines. The first microrocket engine thrust chamber and nozzle design measures 18 x 14 x 3 mm and is fabricated from single crystal silicon using MEMS microfabrication techniques offering the promise of low cost in production. This thesis describes an experimental investigation of bi-propellant microrocket engines and encompasses the fields of materials, microfabrication, combustion and chemical kinetics, instrumentation, packaging, and fluid dynamics. It builds on London's earlier gaseous propellant work, expanding the operating envelope of his motors to higher thrust levels and using these results to design liquid bi-propellant regeneratively cooled engines. Failure analysis of the original devices indicated failures were primarily caused by structural design flaws. Second generation gaseous propellant devices were built and tested. Providing reliable packaging interfaces between the macro test setup and the device proved very difficult. Two packaging methods involving modified geometries and glass seals were developed and allowed higher performance tests. Combustion experiments spanned a range of oxidizer-to-fuel ratios by mass of 1.6 to 2.5 and reached a maximum chamber pressure of 30 bar with a maximum thrust of 3 N at a thrust coefficient of 1.12. A maximum c* of 1650 m/s has been recorded.
(cont.) Experimental results were compared with CFD predictions which suggest that the low thrust coefficient of these devices is due to the overexpansion of gases in the nozzle at the test pressures in combination with the planar extruded nozzle geometry. CFD suggests that at higher chamber pressures the thrust coefficient will approach values up to 90-95 percent of the 1-D ideal case. Experimental values of characteristic exhaust velocity are in agreement with non- adiabatic predictions indicating that combustion is nearly complete. The chamber pressure and thrust limits in the current devices are due to localized failures at bond interfaces in the coolant passages. The potential of the current design is limited to approximately 60 bar by the coolant passage pressure limit, chamber structural limit, and injector manifold pressure limit. Potential liquid propellants for a regeneratively cooled storable bipropellant microrocket engine are examined. The design space for devices using these propellants is explored based on the thermal, structural, and fabrication constraints, and a design for a regeneratively cooled microrocket engine utilizing liquid nitrogen tetroxide and liquid JP-7 as propellants at a vacuum specific impulse of 267 s is presented. Directions for improved specific impulse engines include increasing the engine size by a factor of 2 to 4 and continuing research on hydrogen peroxide as a coolant.
by Christopher S. Protz.
Ph.D.
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Macown, R. J. "Microfabricated devices for adherent stem cell culture." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1465828/.
Повний текст джерелаАнотація:
This thesis details the development of a system of microfabricated devices for the adherent culture of stem cells. The multipotency and self renewal of stem cells make them a potentially abundant source of valuable human cells, for both drug screening and regenerative medicine. However, processing stem cells is challenging due to the complexity of whole cell products, the number of process parameters, and the typical use of adherent culture. It is hypothesised that a microfabricated adherent culture system could facilitate process development with minimal use of resources. Furthermore, microfluidic systems offer advantages in spatial and temporal control over the microenvironment that would benefit process development. An existing prototype culture system is critically evaluated by: assessing the design, modelling fluid flow and dissolved oxygen, and successfully co-culturing human embryonic stem cells, on inactivated mouse embryonic fibroblasts, under perfused conditions. The utilisation of reversible seals facilitates the use of standard tissue-culture polystyrene culture surfaces and manual seeding techniques. The evaluation of the prototype system is used to inform improvements to the design, making it easier to use, increasing the robustness, allowing monitoring of whole culture chambers by microscopy, and improving control over mean pericellular dissolved oxygen. Modelling shows the improved culture system also achieves more uniform distribution of both pericellular dissolved oxygen and fluid velocity. The improved culture system shows similar mouse embryonic stem cell seeding behaviour to tissue culture flasks, but, with medium perfused at 300 μl.h 1, mouse embryonic stem cells reach full confluency in less than 48 h, compared with 72 hours for cells maintained statically in flasks. There is also inconclusive data suggesting that the growth rate is limited by pericellular dissolved oxygen and is, therefore, increased and made more uniform by the inclusion of a gas permeable lid system. The reliability, ease of use, comparability with traditional culture systems, and control over process parameters of the improved system should make it a useful tool for stem cell process development.
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Choudhury, Debaditya. "Femtosecond laser microfabricated devices for biophotonic applications." Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2666.
Повний текст джерелаАнотація:
Femtosecond Laser DirectWriting has emerged as a key enabling technology for realising miniaturised biophotonic applications offering clear advantages over competing soft-lithography, ion-exchange and sol-gel based fabrication techniques. Waveguide writing and selective etching with three-dimensional design flexibility allows the development of innovative and unprecedented optofluidic architectures using this technology. The work embodied in this thesis focuses on utilising the advantages offered by direct laser writing in fabricating integrated miniaturised devices tailored for biological analysis. The first application presented customised the selective etching phenomenon in fused silica by tailoring the femtosecond pulse properties during the writing process. A device with an embedded network of microchannels with a significant difference in aspect-ratio was fabricated, which was subsequently applied in achieving the high-throughput label-free sorting of mammalian cells based on cytoskeletal deformability. Analysis on the device output cell population revealed minimal effect of the device on cell viability. The second application incorporated an embedded microchannel in fused silica with a monolithically integrated near-infrared optical waveguide. This optofluidic device implemented the thermally sensitive emission spectrum of semiconductor nanocrystals in undertaking remote thermometry of the localised microchannel environment illuminated by the waveguide. Aspects relating to changing the wavelength of illumination from the waveguide were analysed. The effect of incorporating carbon nanotubes as efficient heaters within the microchannel was investigated. Spatio-thermal imaging of the microchannel illuminated by the waveguide revealed the thermal effects to extend over distances appreciably longer than the waveguide cross-section. On the material side of direct laser writing, ultra-high selective etching is demonstrated in the well-known laser crystal Nd:YAG. This work presents Nd:YAG as a material with the potential to develop next-generation optofluidic devices.
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Tu, Yudi. "Photo Processing and Microfabrication of Graphene Oxide." Kyoto University, 2018. http://hdl.handle.net/2433/232039.
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Lund, Jason Matthew. "Advanced Techniques for Carbon Nanotube Templated Microfabrication." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7769.
Повний текст джерелаАнотація:
Carbon nanotube templated microfabrication (CNT-M) is a term describing a grouping of processes where carbon nanotubes (CNTs) serve a structural role in the fabrication of a material or device. In its basic form, CNT-M is comprised of two steps: produce a template made from carbon nanotubes and infiltrate the porous template with an additional material. Vertically aligned carbon nanotube (VACNT) templates can be grown to heights ranging from microns to millimeters and lithographically patterned to a desired form. Deposition of an existing thin film material onto a CNT template will coat all template surfaces and can produce a near solid material with dimensions on the millimeter scale with resulting material properties coming primarily from the thin film. Progress within CNT-M falls broadly within one of two categories: control of the CNT template's properties and form, or control of infiltration and new materials.Three-dimensional CNT templates were developed to allow patterned multilayer VACNT structures. In one embodiment, VACNTs were grown below an existing, patterned and capillary-formed VACNT structure by reusing the original catalyst in combination with newly deposited catalyst to create a CNT-based microneedle array on a VACNT support. In another embodiment, VACNTs were mechanically coupled from the initial stages of growth to create a smooth, low porosity surface on which a secondary, patterned CNT forest was grown using standard film deposition and lithographic techniques.A microfabrication compatible thermal barrier was produced using CNTs as a sacrificial template for silicon oxide. The resulting thermal barrier exhibited a thermal conductivity that could be tuned across 2 orders of magnitude based on the degree to which the sacrificial template was removed. Carbon infiltrated carbon nanotubes (CI-CNTs) were produced that exhibited a Young's modulus ranging from 5GPa to 26GPa based on controlled process parameters. Porosity, centroid position, and the second moment of area was calculated from SEM images of CI-CNT structures using an automatic pore identification technique. The porosity results suprisingly show little to no porosity gradient across the width of the structure and a nearly linear increase in porosity from the top to bottom. This work advances the understanding of existing CNT-M processes and demonstrates novel techniques for producing future CNT templates.
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Smith, Ross Andrew. "Biomedical Applications Employing Microfabricated Silicon Nanoporous Membranes." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1278705155.
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McCallum, Grant A. "A Microfabricated Platform for Three-Dimensional Microsystems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1310564363.
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Miller, Raanan Ariel Tai Yu-Chong Tai Yu-Chong. "Microfabricated electromagnetic flap actuators and their applications /." Diss., Pasadena, Calif. : California Institute of Technology, 1997. http://resolver.caltech.edu/CaltechETD:etd-01142008-081338.
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Maiellaro, Kathryn A. "Microfabricated silicon microchannels for cell rheology study." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001145.
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Lohner, Kevin Andrew 1974. "Microfabricated refractory ceramic structures for micro turbomachinery." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9479.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1999.Includes bibliographical references (p. 103-109).
The MIT Microengine Project was initiated in 1995 as a joint effort between the Gas Turbine Laboratory (GTL) and Microsystems Technology Laboratory (MTL) to develop a MEMS-based micro-gas turbine engine. The thermodynamic requirements of power-generating turbomachinery drive the design towards high rotational speeds and high temperatures. To achieve the specified performance requires materials with high specific strength and creep resistance at elevated temperatures. The thermal and mechanical properties of silicon carbide make it an attractive candidate for such an application. Silicon carbide as well as silicon-silicon carbide hybrid structures are being designed and fabricated utilizing chemical vapor deposition of relatively thick silicon carbide layers (10-100 [mu]m) over time multiplexed deep etched silicon molds. The silicon can be selectively dissolved away to yield high aspect ratio silicon carbide structures with features that are hundreds of microns tall. Positive mold, negative mold, and hybrid Si/SiC processing techniques appear to be feasible microfabrication routes with potential for increasing microengine performance. Research has been performed to characterize the capabilities of these processes. Specimens fabricated in the course of this research show very good conformality and step coverage with a fine (~0.1 [mu]m diameter) columnar microstructure. Surface roughness (Rq) of the films is on the order of 100 nm, becoming rougher with thicker deposition. Residual stress limits the achievable thickness, as the strain energy contained within the compressive film increases its susceptibility to cracking. Room temperature biaxial mechanical testing of CVD silicon carbide exhibits a reference strength of 724 MPa with a Weibull modulus, m =16.0. This thesis documents the design trades that led to the selection of CVD SiC as the primary candidate refractory material for the microengine, and the initial experiments performed to assess its suitability and guide future material and process development.
by Kevin Andrew Lohner.
S.M.
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Stillman, Janet Allyn. "Three-dimensional microfabrication with laser-patterned photostructurable glass." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1779690371&sid=28&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Esquivel, Bojorquez Juan Pablo. "Microfabricated Fuel Cells as Power Sources for MEMS." Doctoral thesis, Universitat Autònoma de Barcelona, 2010. http://hdl.handle.net/10803/48532.
Повний текст джерелаАнотація:
La creciente complejidad de los dispositivos electrónicos portátiles demanda fuentes de energía que cumplan con los requerimientos de entregar una alta densidad de potencia en un tamaño reducido y en muchos casos la posibilidad de lograr una completa integración. En este sentido, un intenso trabajo de investigación se ha enfocado hacia la miniaturización de las fuentes de alimentación en una amplia variedad de tecnologías. Una tendencia similar se ha seguido en el campo de los sistemas micro electromecánicos (MEMS), donde el concepto de sistema inteligente o Smart System ha impulsado el desarrollo de una nueva generación de dispositivos de alimentación, tales como baterías, pilas de combustible o generadores de energía, que en conjunto se conocen como powerMEMS. Entre los diferentes sistemas de generación de energía, las micro pilas de combustible han recibido una especial atención debido a sus particulares características, como son la alta densidad de energía, emisiones no-tóxicas y la posibilidad de eliminar partes móviles simplificando el proceso de fabricación y reduciendo la probabilidad de fallo. Las pilas de combustible de electrolito polimérico (PEMFC) son particularmente atractivas debido a su capacidad de trabajar a temperatura ambiente usando hidrógeno o combustibles líquidos. La posibilidad de funcionar con combustibles líquidos, tales como metanol o compuestos orgánicos, representa una ventaja importante para las aplicaciones portátiles debido a la simplicidad de almacenamiento y manipulación del combustible.
En esta tesis se presentan los primeros desarrollos y contribuciones tecnológicas al campo de micro pilas de combustible llevados a cabo en el IMB-CNM (CSIC). En particular, este trabajo está dedicado al estudio de pilas de combustible microfabricadas como fuentes de energía para microsistemas. Esta tesis se compone de siete capítulos: el capítulo de introducción y seis capítulos experimentales divididos en tres secciones.
La primera sección describe el desarrollo de una micro pila de combustible de metanol directo utilizando un enfoque híbrido, el cual fue utilizado para identificar y medir los efectos que más influyen en el rendimiento del dispositivo en la microescala.
La segunda sección presenta las estrategias realizadas respecto a la integración de todos los componentes de la micro pila hacia un dispositivo más compacto utilizando tecnologías de microfabricación compatibles. Estos métodos incluyeron el uso de diferentes técnicas de microestructuración de polímeros como una manera de optimizar las dimensiones del dispositivo, así como la reducción de costes de los materiales y producción.
Por último, la tercera sección presenta dos aplicaciones específicas de las micro pilas de combustible desarrolladas, una bio pila de combustible microfabricada utilizando microorganismos como biocatalizadores de compuestos orgánicos y una plataforma microfluídica alimentada por una micro pila de combustible que puede ser de gran interés para aplicaciones Lab-on-a-Chip o micro Total Analysis Systems (µTAS).The increasing complexity of portable electronic devices demands energy sources that meet the requirement of delivering a high power density within a reduced size, and in many cases the possibility of achieving complete integration. In this sense, an intense research effort has been focused towards the miniaturization of powering devices in a wide variety of technologies. A similar trend has been followed in the micro electromechanical systems (MEMS) technology field, where the smart-system concept has impelled the development of a new generation of powering devices, such as batteries, fuel cells or energy harvesters, which altogether are known as powerMEMS. Among the different energy generation systems, micro fuel cells have received special attention due to their particular features, i.e. high energy density, non-toxic emissions and the possibility of avoiding movable parts simplifying the fabrication process and reducing the risk of failure. Polymer electrolyte membrane fuel cells (PEMFCs) are particularly attractive due to their capability of working at room temperature using both hydrogen and liquid fuels. The possibility to operate using liquid fuels, such as methanol or organic compounds, represent an important advantage for portable applications due to the great simplification of fuel storage and handling processes. This thesis presents the first developments and technological contributions to the micro fuel cell field performed at IMB-CNM (CSIC). Particularly, this work is dedicated to the design and fabrication of microfabricated fuel cells as power sources to be integrated within the microsystems to be powered. The work is organized in seven chapters: one introductory chapter and six experimental chapters that have been divided in three sections. The first section describes the development of a micro direct methanol fuel cell using a hybrid approach, which was used to identify and measure the effects that influence the most on the device performance at a microscale. The second section presents different strategies regarding the integration of all micro fuel cell components into a more compact device by taking advantage of microfabrication compatible technologies. These approaches involved the use of different polymer micropatterning techniques as a way to optimize the device dimensions and reduce materials and production cost. Finally, the third section presents two particular applications of the developed micro fuel cells, a microfabricated bio fuel cell using microorganisms as biocatalysts of organic compounds and a fuel cell powered microfluidic platform that can be of great interest for Lab-on-a-Chip or micro Total Analysis Systems (µTAS).
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Balcells, Ventura Jordi. "Radiation pattern reconfigurable microfabricated planar millimeter-wave antennas." Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/32032.
Повний текст джерелаАнотація:
Els serveis de telecomunicacions i sistemes radar estan migrant a freqüències mil•limètriques (MMW), on es disposa d 'una major amplada de banda i conseqüentment d'una major velocitat de transmissió de dades. Aquesta migració requereix de l'ús de diferents tecnologies amb capacitat d'operar a la banda de freqüències mil•limètriques (30 a 300 Ghz), i més concretament en les bandes Ka (26,5 - 40GHz), V (50 – 75GHz) i W (75 – 110GHz). En moltes aplicacions i sobretot en aquelles on l'antena forma part d'un dispositiu mòbil, es cerca poder utilitzar antenes planes, caracteritzades per tenir unes dimensions reduïdes i un baix cost de fabricació. El conjunt de requeriments es pot resumir en obtenir una antena amb capacitat de reconfigurabilitat i amb un baix nivell de pèrdues en cada una de les bandes de freqüència. Per tal d'afrontar aquests reptes, les dimensions de les antenes mil•limètriques, juntament amb els tipus de materials, toleràncies de fabricació i la capacitat de reconfigurabilitat ens porten a l'ús de processos de microfabricació.
L'objectiu d'aquesta tesis doctoral és l'anàlisi dels conceptes mencionats, tipus de materials, geometries de línia de transmissió i interruptors, en el context de les freqüències mil•limètriques, així com la seva aplicació final en dissenys d'antenes compatibles amb els processos de microfabricació. Finalment, com a demostració s'han presentat dissenys específics utilitzables en tres aplicacions a freqüències mil•limètriques: Sistemes de Comunicació per Satèl•lit (SCS) a la banda Ka, Xarxes d'àrea personal inalàmbriques (WPAN) a la banda V i sistemes radar per l'automoció a la banda W.
La primera part d'aquesta tesis consisteix en l'anàlisi d'algunes tecnologies circuitals a freqüències mil•limètriques. S'han presentat els materials més utilitzats a altes freqüències (Polytetrafluoroethylene or Teflon (PTFE), Quartz, Benzocyclobuten polymer (BCB) i Low Temperature Co-fired Ceramic (LTCC)) i s'han comparat en termes de permitivitat i tangent de pèrdues. També s'inclou un estudi de pèrdues a altes freqüències en les principals línies de transmissió (microstrip, stripline i CPW). Finalment, es presenta un resum dels interruptors RF-MEMS i es comparen amb els PIN diodes i els FET.
En la segona part, es presenten diferents agrupacions d'antenes amb la capacitat de reconfigurar la polarització i la direcció d'apuntament. S'han dissenyat dos elements base reconfigurables en polarització: CPW Patch antena i 4-Qdime antena. La primera antena consisteix en un element singular amb interruptors RF-MEMS, dissenyada per operar a les bandes Ka i V. La segona antena consisteix en una arquitectura composta on la reconfigurabilitat en polarització s'obté mitjançant variant la fase d'alimentació de cada un dels quatre elements lineals. La fase és controlada mitjançant interruptors RF-MEMS ubicats en la xarxa de distribució. L'antena 4-Qdime s'ha dissenyat per operar en les bandes V i W. Ambdós elements base s'han utilitzat posteriorment pel disseny de dues agrupacions d'antenes amb capacitat de reconfigurar l'apuntament del feix principal. La reconfigurabilitat es dur a terme utilitzant desfasadors de fase d'1 bit.
La part final de la tesis es centra en les toleràncies de fabricació i en els processo de microfabricació d'agrupacions d'antenes mil•limètriques. Les toleràncies de fabricació s'han estudiat en funció dels error d'amplitud i fase en cada element de l'agrupació, fixant-se en les pèrdues de guany, error d'apuntament, error en l'amplada de feix, errors en el nivell de lòbul secundari i en l'error en la relació axial. El procés de microfabricació de les diferents antenes dissenyades es presenta en detall. Els dissenys de l'antena CPW Patch reconfigurable en polarització i apuntament operant a les bandes Ka i V, s'han fabricat en la sala blanca del Cornell NanoScale Science & Technology Facility (CNF). Posteriorment, s'han caracteritzat l'aïllament i el temps de resposta dels interruptors RF-MEMS, i finalment, el coeficient de reflexió, el diagrama de radiació i la relació axial s'han mesurat a les bandes Ka i V per les antenes configurades en polarització lineal (LP) i circular (CP).Telecommunication services and radar systems are migrating to Millimeter-wave (MMW) frequencies, where wider bandwidths are available. Such migration requires the use of different technologies with the capability to operate at the MMW frequency band (30 to 300GHz), and more specifically at Ka- (26.5 to 40GHz), V- (50 to 75GHz) and W-band (75 to 110GHz). For many applications and more concretely those where the antenna is part of a mobile device, it is targeted the use of planar antennas for their low profile and low fabrication cost. A wide variety of requirements is translated into a reconfiguration capability and low losses within each application frequency bandwidth. To deal with the mentioned challenges, the MMW antenna dimensions, together with the materials, fabrication tolerances and reconfigurability capability lead to microfabrication processes. The aim of this thesis is the analysis of the mentioned concepts, materials, transmission lines geometries and switches in the MMW frequencies context and their final application in antenna designs compatible with microfabrication. Finally, specific designs are presented as a demonstration for three MMW applications: Satellite Communication Systems (SCS) at Ka-band, Wireless Personal Area Network (WPAN) at V-band and Automotive Radar at W-band. The first part of this thesis consist to analyze some MMW circuit technologies. The four most used materials at MMW frequencies (Polytetrafluoroethylene or Teflon (PTFE), Quartz, Benzocyclobuten polymer (BCB) and Low Temperature Co-fired Ceramic (LTCC)) have been presented and compared in terms of permittivity (εr) and loss tangent (tanδ). An study of the main transmission lines attenuation (microstrip, stripline and CPW) at high frequencies is included. Finally, an overview of the RF-MEMS switches is presented in comparison with PIN diodes and FETS switches. The second part presents different polarization and beam pointing reconfigurable array antennas. Two polarization-reconfigurable base-elements have been designed: CPW Patch antenna and 4-Qdime antenna. The first consists of a single reconfigurable element with integrated RF-MEMS switches, designed to operate at Ka- and V-band. The second antenna presented in this thesis has a composed architecture where the polarization reconfigurability is obtained by switching the phase feeding for each of the four linear polarized elements in the feed network with RF-MEMS switches. The 4-Qdime antenna has been designed to operate at V- and W-band. The two base-elements have been used to design two beam pointing reconfigurable antenna arrays. Using phased array techniques, beamsteering is computed and implemented with 1-bit discrete phase-shifter. The final part of the thesis is focused into the fabrication tolerances and microfabrication process of Millimeter-wave antenna arrays. The fabrication tolerances have been studied as a function of the amplitude and phase errors presented at each elements array, focusing on the gain loss, beam pointing error, Half-Power Beamwidth (HPBW) error, sidelobe level error and axial ratio error. The microfabrication process for the designed antennas is presented in detail. Polarization- and pointing- reconfigurable CPW Patch antenna operating at Ka- and V- band have been fabricated in a clean-room facility at Cornell NanoScale Science & Technology Facility (CNF). The RF-MEMS switches isolation and time response have been characterized. Finally, the reflection coefficient, radiation pattern and axial ratio have been measured at Ka- and V-band for the fabricated antennas configured in Linear Polarization (LP) and Circular Polarization (CP).
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McLeod, Logan Scott. "Hydrogen permeation through microfabricated palladium-silver alloy membranes." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31672.
Повний текст джерелаАнотація:
Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Fedorov, Andrei; Committee Co-Chair: Degertekin, Levent; Committee Member: Koros, William; Committee Member: Liu, Meilin; Committee Member: Mayor, J. Rhett. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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McBrady, Adam Dewey. "Microfabricated chromatographic instrumentation for micro total analysis systems /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8570.
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Serrell, David Brewster. "A novel, microfabricated device for single cell studies." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3239389.
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Shah, Vishal. "Microfabricated atomic clocks based on coherent population trapping." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3256459.
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Mansoor, Hadi. "Microfabricated electromagnetic actuators for confocal measurements and imaging." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44146.
Повний текст джерелаАнотація:
Various optical microscopy techniques have been developed for micrometer level imaging of biological tissue samples. Among those techniques, confocal imaging provides superior image contrast and high resolution with a modest system cost. Confocal microscopy allows vertical optical sectioning (imaging a section perpendicular to the surface of tissue) or horizontal optical sectioning (imaging a section parallel to the surface of tissue) and provides high-resolution tissue morphology that is analogous to conventional histopathology images. This has brought up a tremendous potential for guiding surgical biopsies and in vivo non-invasive diagnosis of diseases such as cancer. The challenge in moving microscopic imaging modalities into clinical applications is miniaturization into a form of hand-held devices or catheters for endoscopic applications.
In this thesis, micro-fabrication techniques such as Microelectromechanical Systems (MEMS) fabrication process and laser micromachining have been employed to develop magnetic actuators. The actuators are then used to move lenses and optical fibers in order to scan a laser beam across a sample. Lens and fiber actuators are integrated in catheter and hand-held devices for confocal thickness measurement and optical sectioning imaging of biological samples.
Thickness measurement is performed by scanning the focal point of a microlens across the thickness of thin films or layered biological tissues and collecting the intensity signal of the single scattering light reflected back from the samples as a function of lens position. A catheter was developed and thickness measurements of polymer layers and biological tissues were demonstrated. The device has optical resolution of 32 µm with expanded uncertainty of measurement of 11.86 µm.
Lens and fiber optic actuators have been coupled to form two-dimensional imaging devices. Direct and real-time vertical and horizontal cross-sectional imaging of biological samples has been demonstrated. Vertical imaging is performed by transverse (X-axis) and axial (Z-axis) scanning of a focused laser beam using an optical fiber and a microlens actuator respectively. Horizontal imaging is done by a 2-axis fiber optic scanner. All the developed actuators are driven by electromagnetic forces and require low driving voltages. Confocal imaging of biological samples, with lateral resolution of 1.55 µm, has been demonstrated.
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Shaikh, Fayaz A. "Monolithic microfabricated ion trap for quantum information processing." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47597.
Повний текст джерелаАнотація:
The objective of this research is to design, fabricate, and demonstrate a microfabricated
monolithic ion trap for applications in quantum computation and quantum simulation.
Most current microfabricated ion trap designs are based on planar-segmented surface electrodes.
Although promising scalability to trap arrays containing ten to one hundred ions,
these planar designs suffer from the challenges of shallow trap depths, radial asymmetry of
the confining potential, and electrode charging resulting from laser interactions with dielectric
surfaces. In this research, the design, fabrication, and testing of a monolithic
and symmetric two-level ion trap is presented. This ion trap overcomes the challenges of
surface-electrode ion traps. Numerical electrostatic simulations show that this symmetric
trap produces a deep (1 eV for 171Yb+ ion), radially symmetric RF confinement potential.
The trap has an angled through-chip slot that allows back-side ion loading and generous
through laser access, while avoiding surface-light scattering and dielectric charging that
can corrupt the design control electrode compensating potentials. The geometry of the trap
and its dimensions are optimized for trapping long and linear ion chains with equal spacing
for use with quantum simulation problems and quantum computation architectures.