Dissertations / Theses on the topic 'Micro Electro Mechanical Systems'
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Dean, Julian Sebastian. "Magnetic micro electro-mechanical systems." Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444255.
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Fu, Y. "Micro-electro-mechanical systems and nanotechnology." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599251.
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Micro-Electro-Mechanical-System (MEMS) and Nanotechnology have both received significant attention in recent years due to their potential for manufacturing highly miniaturised devices which consume less raw materials and energy in their production, and function with greater efficiency, speed, and reliability. The first project described in this thesis concerns the development of a novel, low cost, contamination-free nanofabrication system. This system is enabled by a MEMS-based device which has the dual functions of a high-precision AFM (Atomic Force Microscope) cantilever probe and a shadow mask. This MEMS device, which is referred to as the Nanostencil device in this thesis, has been integrated with nanoscale apertures and an AFM scanning tip using the Focussed Ion Beam (FIB) technique. The finished Nanostencil device has been used successfully for both parallel nanoscale depositions and high precision nanoscale alignments. The second project presented in this thesis is concerned with the application of MEMS technology to benefit the aircraft industry by providing a compact and robust pressure sensor capable of measuring high frequency turbulent flow velocities with improved accuracy. The information provided by such probes could be of considering help in improving the design of the next generation of aeroplanes. With the help of finite-element analysis, a pressure sensor has been designed which has a footprint of 0.7 mm, a frequency response of a few megahertz and a high thermal stability. The fabrication of this prototype has been realised through a specially developed process sequence utilising a Deep Reactive-Ion-Etching (DRIE) system. Mechanical testing of the deflection versus pressure response of the sensor provides preliminary indications that the fabricated device meets the design requirements.
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Wang, Xuan-Qi Tai Yu-Chong. "Integrated parylene micro electro mechanical systems (MEMS) /." Diss., Pasadena, Calif. : California Institute of Technology, 2000. http://resolver.caltech.edu/CaltechETD:etd-09062005-112235.
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Zohur, Abdul. "Micro-Electro-Mechanical Systems (MEMS) Integrated Frequency Reconfigurable Antenna." DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1731.
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In this paper, the design, analysis, and characterization of reconfigurable antennas based on radio frequency micro-electro-mechanical systems (RF MEMS) operating in the United States' public safety (PS) bands are presented. The design methodology of these antennas, which are different from the normal antenna design, is also reported. In this thesis, two electrically small reconfigurable antenna designs have been presented, with two and three modes of operation, and central frequencies of 718 and 4960 MHz and of 857,809 and 4960 MHz, respectively. The maximum frequency tunable ratio achieved in these designs is 7. The recongurability between the modes is achieved by one and three RF MEMS switches in all three designs. These switches enable a change in the length of the current flow path, thereby changing the resonance frequencies. The measurement results for impedance and radiation characteristics of the fabricated antennas prototypes are also presented, and agree reasonably well with the simulations results from An-soft HFSS.
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Morgan, Christopher James. "MICRO ELECTRO-DISCHARGE MACHINING: TECHNIQUES AND PROCEDURES FOR MICRO FABRICATION." Lexington, Ky. : [University of Kentucky Libraries], 2004. http://lib.uky.edu/ETD/ukymeen2004t00197/MicroEDM.pdf.
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Thesis (m.s.)--University of Kentucky, 2004.Title from document title page (viewed Jan. 5, 2005). Document formatted into pages; contains viii, 77p. : ill. Includes abstract and vita. Includes bibliographical references (p. 74-76).
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Martyniuk, Mariusz. "Low-temperature micro-opto-electro-mechanical technologies for temperature sensitive substrates." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2006. http://theses.library.uwa.edu.au/adt-WU2007.0042.
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[Truncated abstract] The salient feature of next generation infrared (IR) on-chip integrated sensors is likely to be sensitivity in a narrow wavelength band that is tuneable over a selected range of the IR spectrum. It is proposed that this can be achieved by the integration of present-day HgCdTe IR detectors with thin-film based microelectro- mechanical systems (MEMS) optical mirror technology. Narrow-band sensitivity is obtained by optical resonance phenomena within a Fabry-Perot (FP) cavity, that is created by two Bragg reflectors and is monolithically integrated with an HgCdTe IR detector. Electrostatic actuation of the thin-film membrane supported Bragg reflector is the means of providing wavelength discrimination of the incident IR photons which, for example, could be used for target discrimination or detection of various chemical/biological species via identification of narrow spectral features . . . The outcomes from this thesis have been incorporated into a monolithic integrated technology comprising low-temperature MEMS and HgCdTe IR detector technology. The integrated technology has been shown to be viable, and successful prototypes have been fabricated. Structural properties of the SiNx, SiOx, and Ge layers encompassed in the suspended IR reflector have allowed for IR photon detection in a narrow wavelength band with full-width at halfmaximum of ∼100nm that is tunable over a wavelength range from 2.2 to 1.85μm using a maximum tuning voltage of only 7.5V. Although the thesis objectives have been focused on a specific application related to multi-spectral IR detection technology as a demonstration vehicle, the findings of this thesis are directly applicable to any MEMS technologies that are to be merged with temperaturesensitive substrates/materials.
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Assadsangabi, Babak. "Investigation and development of ferrofluid enabled micro-electro-mechanical systems." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50339.
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Ferrofluids are magnetic fluids that can be manipulated using magnetic field. Ferrofluids have unique properties that have led to various interesting applications. Although, currently they are being used in few commercial products in macro-scale domain, there has been limited success in their applications in micro- devices and microactuators in specific.
Literature review shows various efforts to develop ferrofluid-based microactuators however, most of them have utilized non-integrated means (e.g. external magnets or solenoids) to provide the necessary magnetic field for ferrofluid manipulation that inherently limit their application as a micro-device. Moreover, previous ferrofluid-based microactuators with integrated solutions (e. g. microfabricated coils) could only provide unidirectional forces which limited their application range.
In the present thesis, development of integrated ferrofluid-based microactuators is investigated. A new actuation method that uses planar spiral coils with bias fields is proposed to enable bidirectional ferrofluid manipulation. To demonstrate the potentials of the proposed actuation method, two proof-of-concept devices were developed. Active mirror cells with variable reflectivity were demonstrated as the first device and then a variable planar inductor with ferrofluid as a moving magnetic core was developed and characterized.
Another interesting application of ferrofluids in passive levitation of permanent magnets is also investigated for moving magnet based microactuators. Using this levitation mechanism a structurally simple and reliable microbearing is demonstrated. In order to demonstrate the effectiveness of such microbearing, a linear micromotor is first characterized and demonstrated. Also, frictional force and load carrying capacity of such microbearing is investigated showing very low frictional forces with good load bearing capabilities. Given the promising results in the developed linear micromotor, a rotary micromotor with small axial size is developed for minimally invasive endoscopy applications. The characterization of developed prototype shows its potential to be used for real time medical imaging.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Embargo expired 2014-02-28. Embargo reinstated to 2015-03-31 by tara.stephens@ubc.ca on 2015-03-02 as per G+PS
Graduate
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Leong, Jonathan Yonghui. "Lubrication and tribological performance optimizations for micro-electro-mechanical systems." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/18067.
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Lubricants and lubrication have been of great interest to mankind since the introduction of machines with sliding/rolling surfaces into everyday life. With the recent trend of miniaturization, Micro-Electro-Mechanical Systems (MEMS) have taken centre stage, featuring components with scales in dimensions as small as nanometres. In this PhD study, two approaches to solving MEMS tribology problems have been pursued. First, a novel direct lubrication method using well-known lubricants such as perfluoropolyether (PFPE) and multiply alkylated cyclopentane (MAC) was developed and tested using reciprocating sliding and actual MEMS tribometry. The second approach utilized the concept of hydrodynamic lubrication and selective surface modification for MEMS. To combat spreading and starvation of lubricants in small contacts such as in MEMS, selective modification of the silicon surface with hydrophobic (non-wetting) and hydrophilic (wetting) portions was carried out and found to increase the force required to move a droplet of lubricant from a designated location on the surface. Octadecylamine and dodecylamine were also used as additives to successfully induce autophobicity in hexadecane, and the various spreading behaviours investigated. In conclusion, several new approaches to tackling tribological problems in MEMS have been researched. These methods are easily adapted to suitable MEMS devices and greatly reduce adhesion and friction, and increase wear and device life by several orders of magnitude.
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Yildirim, Alper. "Development Of A Micro-fabrication Process Simulator For Micro-electro-mechanical-systems(mems)." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606850/index.pdf.
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ABSTRACT
DEVELOPMENT OF A MICRO-FABRICATION PROCESS SIMULATOR FOR MICRO-ELECTRO-MECHANICAL SYSTEMS (MEMS)
Yildirim, Alper
M.S, Department of Mechanical Engineering
Supervisor: Asst. Prof. Dr. Melik Dölen December 2005, 140 pages The aim of this study is to devise a computer simulation tool, which will speed-up the design of Micro-Electro-Mechanical Systems by providing the results of the micro-fabrication processes in advance. Anisotropic etching along with isotropic etching of silicon wafers are to be simulated in this environment. Similarly, additive processes like doping and material deposition could be simulated by means of a Cellular Automata based algorithm along with the use of OpenGL library functions. Equipped with an integrated mask design editor, complex mask patterns can be created by the software and the results are displayed by the Cellular Automata cells based on their spatial location and plane. The resultant etched shapes are in agreement with the experimental results both qualitatively and quantitatively. Keywords: Wet Etching, Anisotropic Etching, Doping, Cellular Automata, Micro-fabrication simulation, Material Deposition, Isotropic Etching, Dry Etching, Deep Reactive Ion Etching
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Tsao, Che-Chih. "Photo-electroforming, a new manufacturing process for micro-electro-mechanical systems." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/38039.
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Liu, Lixian Ph D. Massachusetts Institute of Technology. "Theory for hydrostatic gas journal bearings for micro-electro-mechanical systems." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33921.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005."September 2005."
Includes bibliographical references (p. [281]-283).
The goal of the MIT micro-engine project is to develop high-speed rotating Power MEMS (Micro-Electro-Mechanical Systems) using computer chip fabrication technologies. To produce high power (10-50 W) in a small volume (less than one cubic centimeter), the micro-turbo-machinery must be spun at a rotational speed on the order of million rpm. This ultra-high rotational speed, together with the small length-to-diameter ratio (L/D<0.07) limited by the chip manufacturing technology, entails many challenges in the design of the bearing system, such as an ultra-high whirl ratio of over 20 (compared with a whirl ratio of 2 for large-scale journal bearings) and a DN number of order 10 million mm-rpm. The thesis presents a newly developed theory for the hydrostatic gas journal- bearings for the micro-engine devices. To investigate the underlying physical mechanisms, fluid models are established to analytically calculate the hydrostatic, hydrodynamic, and damping bearing forces. It is found from first principles that the hydrodynamic force due to viscous drag becomes dominant with an L/D<<1 and acts in the opposite direction of the hydrodynamic force due to rotor pumping action.
(cont.) As a result, the net destabilizing hydrodynamic force can vanish for certain bearing geometries, causing singular behavior in the whirl instability limit. Thus, the ultra-short bearing is suggested to enable a large DN number and a high whirl ratio in the micro-journal-bearing system. A novel variation of the axial-flow hydrostatic micro gas journal-bearing concept is introduced, which yields anisotropy in bearing stiffness. By departing from axial symmetry and introducing biaxial symmetry in hydrostatic stiffness, the bearing's top speed is increased and the fabrication tolerance requirements are substantially relieved. The third-order nonlinear resonances in the micro-journal-bearing system are investigated by both analytical models and numerical simulations, and the predictions from these models agree well with the experimental observations. The model predicts a subharmonic resonance in the isotropic journal-bearing system, with a slow rotating noncircular orbit such that the symmetry of the system is broken by itself in the nonlinear resonance.
(cont.) Furthermore, the anisotropic journal-bearing system is found to be able to engage in multi-type nonlinear resonances: superharmonic resonances at one third of the natural frequencies, subharmonic resonances at three times the natural frequencies, and combinations (such as the average) of the two natural frequencies. The conditions under which these resonances can occur are derived analytically and are then verified by numerical simulation.
by Lixian Liu.
Ph.D.
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Li, Lijie. "Microactuators and their application in micro-opto-electro-mechanical systems (MOEMS)." Thesis, University of Strathclyde, 2004. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21529.
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Microactuators are active elements for microelectromechanical systems (MEMS), and are used to provide force to move the MEMS device in the way required. Therefore, their force characteristics, displacement capabilities and velocity ranges are of importance, and require to be investigated. Scratch drive actuators, thermal actuators, and comb drive actuators have separately been characterized, improved, and modified in this thesis. Asymmetric thermal actuators are current driven actuators that can generate relatively high force and can be operated bi-directionally. We have designed a novel structure that has a higher displacement than traditional asymmetric actuators. The increment of maximum displacement is about 20 % above the displacement of the ordinary asymmetric thermal actuators. Detailed electro - thermal heat dissipation and expansion - deflection mechanical analyses has been performed to advance the idea. Device prototypes have been designed and the fabricated devices were tested; the experimental results show a good match to the theoretical analysis. Scratch drive actuators (SDAs) have been modelled and characterized both on travel and force performances. Long linear travel SDAs have been designed and the fabricated devices characterized by using a high-speed camera. Detailed motion has been recorded. A theory for flexing of SDA plates has been developed. Voltage - step size relation has been obtained by theoretical analysis. Theoretical and experimental results have then been compared. Force characteristics of single and multi-plate SDAs driven by different voltages have been measured by means of micro box springs. The SDA typical step size has been measured to be 7 nm at 60 V and 100 HZ driving condition. Typically, a 4 stage SDA driven with 200 Volts produces a force of 850 µN. Comb drive actuators are commonly used in resonators, which need high Q factors. However in some applications, such as optical choppers, they require low Q factors so that they can be operated over a large frequency range. We have designed a comb drive actuator with spring that can be operated from a few Hz up to 5 kHz. The static and dynamic testing and theoretical analysis have been undertaken in this thesis. A variable optical attenuator (VOA) has been designed, and fabricated by surface micromachining using PolyMUMPs (Polysilicon Multi-User MEMS Processes) foundry process. The principle is simply interrupting the light beam by a vertical microshutter. An array of SDAs have been used to drive the microshutters. Microhinges are employed to build the vertical microshutter. Stress-induced beams are used to self-assemble the microshutter. Optical simulation of the VOA has been performed using Rayleigh-Sommerfield diffraction theory. Devices have also been tested with single mode optical fibres. Testing results show a dynamic range of 34.2 dB. The VOA structure was driven at a speed of 1.6 µm/s at 150 volts and 100 Hz driving condition. An optical chopper has been realized by a pair of comb drive actuators driving two shutters. Two shutters are employed to double the response time. The device has been designed and fabricated using SOIMUMPs (Silicon On Insulator Multi-User MEMS Processes) foundry process. Completely design, simulation and testing of the chopper has been undertaken. The attenuation range of chopper has been measured to be from - 1.4 dB to - 29 dB. The response time of the chopper has been measured to be 90 µs.
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Unamuno, Anartz. "Hybrid micro-opto-electro-mechanical systems (MOEMS) based on electrothermal microactuation." Thesis, University of Strathclyde, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501835.
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Xue, Linfeng. "Theoretical Characterization of Internal Resonance in Micro-Electro-Mechanical Systems (MEMS)." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1593296130150349.
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Ospanov, Asset. "DELAY DIFFERENTIAL EQUATIONS AND THEIR APPLICATION TO MICRO ELECTRO MECHANICAL SYSTEMS." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5674.
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Delay differential equations have a wide range of applications in engineering. This work is devoted to the analysis of delay Duffing equation, which plays a crucial role in modeling performance on demand Micro Electro Mechanical Systems (MEMS). We start with the stability analysis of a linear delay model. We also show that in certain cases the delay model can be efficiently approximated with a much simpler model without delay. We proceed with the analysis of a non-linear Duffing equation. This model is a significantly more complex mathematical model. For instance, the existence of a periodic solution for this equation is a highly nontrivial question, which was established by Struwe. The main result of this work is to establish the existence of a periodic solution to delay Duffing equation. The paper claimed to establish the existence of such solutions, however their argument is wrong. In this work we establish the existence of a periodic solution under the assumption that the delay is sufficiently small.
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Hong, Young Ki. "Surface tension self-assembly for three dimensional micro-opto-electro-mechanical systems." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429321.
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Nath, Pulak. "MEMS (Micro-Electro-Mechanical-Systems) Based Microfluidic Platforms for Magnetic Cell Separation." Cleveland State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=csu1210043552.
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Sun, Mingrui. "Detection and Manipulation of Bioparticles with Micro-Electro-Mechanical Systems and Microfluidics." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1511959678485578.
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Mopidevi, Hema Swaroop. "Micro Electro Mechanical Systems Integrated Frequency Reconfigurable Antennas for Public Safety Applications." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/744.
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This thesis work builds on the concept of reconfiguring the antenna properties (frequency, polarization, radiation pattern) using Radio Frequency (RF) Micro Electro Mechanical Systems (MEMS). This is a part of the overall research performed at the RF Micro/Nano Electro Mechanical Systems (uNeMS) Laboratory at Utah State University, which includes design, microfabrication, test, and characterization of uNeMS integrated cognitive wireless communication systems (Appendix A).
In the first step, a compact and broadband Planar Inverted F Antenna (PIFA) is designed with a goal to accommodate reconfigurability at a later stage. Then, a Frequency Reconfigurable Antenna (FRA) is designed using MEMS switches to switch between the Public Safety (PS) bands, 152-162 MHz and 406-512 MHz, while maintaining the integrity of radiation pattern for each band. Finally, robust mechanical designs of the RF MEMS switches accompanied by different analyses have been performed. These analyses are instrumental in obtaining high yield, reliable, robust microfabrication processes including thin film metal deposition and patterning.
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Bowman, Amy Catherine. "A selective encapsulation solution for packaging an optical micro electro mechanical system." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0108102-140953.
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Thesis (M.S.)--Worcester Polytechnic Institute.Keywords: packaging; micro electro mechanical systems; MEMS; electronics; die warpage; die bow; encapsulant; encapsulate; electrochemical migration; corrosion; wirebonds. Includes bibliographical references (p. 94-99).
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Barron, Lance W. "High-reflectance, sputter-deposited aluminum alloy thin films for micro-electro-mechanical systems /." Online version of thesis, 2005. http://hdl.handle.net/1850/5195.
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Wang, Xin 1972 Jan 8. "FastStokes : a fast 3-D fluid simulation program for micro-electro-mechanical systems." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/29229.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 150-153).
We have developed boundary integral equation formulas and a corresponding fast 3-D Stokes flow simulation program named FastStokes to accurately simulate viscous drag forces on geometrically complicated MEMS (micro- electro- mechanical systems) devices. Unlike the 3-D finite element or finite difference solvers which often take days to run to completion or fail when geometry gets complicated, the FastStokes 3.0 simulation program is capable of simulating complicated devices such as resonators, accelerometers, and micro-mirrors on PC computers in minutes. The FastStokes 3.0 simulation program is a fast 3-D boundary-element simulation program that uses only surface discretizations. The implementation of the Precorrected-FFT algorithm in combination with the GMRES algorithm substantially improves the speed of this simulation program. An efficient two-step approach that successfully handles the null space of the singular incompressible Stokes BEM operators is developed to avoid numerical errors and solution discontinuities. An analytical flat-panel kernel integration algorithm is implemented in FastStokes and an accurate curved-panel integration algorithm is also developed. Both an incompressible FastStokes solver and a compressible FastStokes solver have been developed and tested. They are not only fast, but also accurate. The incompressible FastStokes solver solves the steady incompressible Stokes equation; the effectiveness of this fast solver has been repeatedly proved by the close matches between numerical simulation results and experiments, within engineering accuracy (5-10% error).
(cont.) The numerical simulation results of a comb drive resonator, the ADXL 76 accelerometer, and a micro-mirror are given. The compressible FastStokes solver solves a linearized compressible Stokes equation that is also capable of capturing the weak air compression effect in MEMS devices. Therefore, the compressible FastStokes solver is a more general simulation program, and it is especially useful when the strength of the fluid compression effect is uncertain. The solutions of the compressible FastStokes are compared with the analytical solutions of the linearized compressible Reynolds equation. Numerical simulations of some common structures that may exhibit compression effect when packaged in gases are also given.
by Xin Wang.
Ph.D.
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Latif, Rhonira. "Microelectromechanical systems for biomimetical application." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7955.
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The application of adaptive micro-electro-mechanical systems (MEMS) device in biologically-inspired cochlear model (cochlear biomodel) has been seen as a preferable approach to mimic closely the human cochlear response. The thesis focuses on the design and fabrication of resonant gate transistor (RGT) device applied towards the development of RGT cochlear biomodel. An array of RGT devices can mimic the cochlea by filtering the sound input signals into multiple electrical outputs. The RGT device consists of two main components; a) the MEMS bridge gate structure that transduces the sound input into mechanical vibrations and b) the channel with source/drain regions underneath the bridge gate structure that transduce the mechanical vibrations into electrical signals. The created mathematical model for RGT calculates the electrical outputs that are suited for neural spike coding. The neuromorphic auditory system is proposed by integrating the RGT devices with the spike event interface circuits. The novelty of the system lies in the adaptive characteristics of the RGT devices that can self-tune the frequency and sensitivity using the feedback control signals from the neuromorphic circuits. The bridge gates have been designed to cover the audible frequency range signals of 20 Hz - 20 kHz. Aluminium and tantalum have been studied as the material for the bridge gate structure. The fabrication of a bridge gate requires a gentle etch release technique to release the structure from a sacrificial layer. The downstream etch release technique employing oxygen/nitrogen plasma has been introduced and characterised. In the first iteration, aluminium bridge gates have been fabricated. The presence of tensile stress within aluminium had caused the aluminium bridge gates of length >1mm to collapse. In order to address this issue, tantalum bridge gates have been fabricated in the second iteration. Straight tantalum bridge gates in tensile stress and buckled tantalum bridge gates in compressive stress have been characterised. The frequency range of 550 Hz - 29.4 kHz has been achieved from the fabricated tantalum bridge gates of length 0.57mm - 5.8mm. The channel and source/drain regions have been fabricated and integrated with the aluminium or tantalum bridge gate structures to create the RGTs. In this study, the n-channel and p-channel resonant gate transistor (n-RGT and p-RGT) have been considered. In n-RGT, phosphorus ions are implanted to form the source/drain regions. High subthreshold currents have been measured from the n-RGTs. Thus, p- RGTs have been employed with considerably small subthreshold current. In p-RGT, boron ions are implanted to form the source/drain regions. The threshold voltage, transconductance and subthreshold current for both n-channel and p-channel resonant gate transistor devices have been characterised. In this work, the channel conductance of the n-RGT and p-RGT devices has been modulated successfully and the sensitivity tuning within the audible frequency range has been achieved from the tantalum bridge gates of the p-RGT devices. The characterisation and optimisation of the resonant gate transistor provide the first step towards the development of the adaptive RGT cochlear biomodel for the neuromorphic auditory system application.
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Dinh, Toan Khac. "Thermoresistive Effect for Advanced Thermal-Based Sensors." Thesis, Griffith University, 2017. http://hdl.handle.net/10072/365574.
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Thermoresistive effects in semiconductors (e.g. silicon) and metals (e.g. platinum) have been widely utilized to develop MEMS (Micro Electro-Mechanical Systems) thermal-based sensors. Thanks to their simplicity in design and implementation using conventional MEMS technologies, these sensors have been found in a wide range of applications, including temperature sensing, flow monitoring and acceleration measurement. However, their material cost, inflexibility, inadequate sensitivity and, especially, their lack
of ability to work in harsh environments impede these devices in many applications, particularly where the temperature is high. Therefore, there is a strong demand for investigating the alternative materials with high thermosensitivity for niche thermal-based sensors. This research aims to theoretically and experimentally investigate thermoresistive effect in a group of semiconductors (e.g. silicon, silicon carbide and graphite) for niche and advanced thermal-based sensors such as high-temperature sensors, low-cost
and highly sensitive thermoresistive sensors, and flexible/wearable sensors for healthcare applications.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
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Martinez, Jose Antonio. "A Micro-Opto-Electro-Mechanical System (MOEMS) for Microstructure Manipulation." FIU Digital Commons, 2008. http://digitalcommons.fiu.edu/etd/206.
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Microstructure manipulation is a fundamental process to the study of biology and medicine, as well as to advance micro- and nano-system applications. Manipulation of microstructures has been achieved through various microgripper devices developed recently, which lead to advances in micromachine assembly, and single cell manipulation, among others. Only two kinds of integrated feedback have been demonstrated so far, force sensing and optical binary feedback. As a result, the physical, mechanical, optical, and chemical information about the microstructure under study must be extracted from macroscopic instrumentation, such as confocal fluorescence microscopy and Raman spectroscopy. In this research work, novel Micro-Opto-Electro-Mechanical-System (MOEMS) microgrippers are presented. These devices utilize flexible optical waveguides as gripping arms, which provide the physical means for grasping a microobject, while simultaneously enabling light to be delivered and collected. This unique capability allows extensive optical characterization of the structure being held such as transmission, reflection, or fluorescence. The microgrippers require external actuation which was accomplished by two methods: initially with a micrometer screw, and later with a piezoelectric actuator. Thanks to a novel actuation mechanism, the “fishbone”, the gripping facets remain parallel within 1 degree. The design, simulation, fabrication, and characterization are systematically presented. The devices mechanical operation was verified by means of 3D finite element analysis simulations. Also, the optical performance and losses were simulated by the 3D-to-2D effective index (finite difference time domain FDTD) method as well as 3D Beam Propagation Method (3D-BPM). The microgrippers were designed to manipulate structures from submicron dimensions up to approximately 100 µm. The devices were implemented in SU-8 due to its suitable optical and mechanical properties. This work demonstrates two practical applications: the manipulation of single SKOV-3 human ovarian carcinoma cells, and the detection and identification of microparts tagged with a fluorescent “barcode” implemented with quantum dots. The novel devices presented open up new possibilities in the field of micromanipulation at the microscale, scalable to the nano-domain.
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Cozzani, Enrico <1977>. "Modeling, design and experimental characterization of Micro-Electro-Mechanical-Systems for gas chromatographic applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3669/1/cozzani_enrico_tesi.pdf.
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Design parameters, process flows, electro-thermal-fluidic simulations and experimental characterizations of Micro-Electro-Mechanical-Systems (MEMS) suited for gas-chromatographic (GC) applications are presented and thoroughly described in this thesis, whose topic belongs to the research activities the Institute for Microelectronics and Microsystems (IMM)-Bologna is involved since several years, i.e. the development of micro-systems for chemical analysis, based on silicon micro-machining techniques and able to perform analysis of complex gaseous mixtures, especially in the field of environmental monitoring.
In this regard, attention has been focused on the development of micro-fabricated devices to be employed in a portable mini-GC system for the analysis of aromatic Volatile Organic Compounds (VOC) like Benzene, Toluene, Ethyl-benzene and Xylene (BTEX), i.e. chemical compounds which can significantly affect environment and human health because of their demonstrated carcinogenicity (benzene) or toxicity (toluene, xylene) even at parts per billion (ppb) concentrations.
The most significant results achieved through the laboratory functional characterization of the mini-GC system have been reported, together with in-field analysis results carried out in a station of the Bologna air monitoring network and compared with those provided by a commercial GC system.
The development of more advanced prototypes of micro-fabricated devices specifically suited for FAST-GC have been also presented (silicon capillary columns, Ultra-Low-Power (ULP) Metal OXide (MOX) sensor, Thermal Conductivity Detector (TCD)), together with the technological processes for their fabrication.
The experimentally demonstrated very high sensitivity of ULP-MOX sensors to VOCs, coupled with the extremely low power consumption, makes the developed ULP-MOX sensor the most performing metal oxide sensor reported up to now in literature, while preliminary test results proved that the developed silicon capillary columns are capable of performances comparable to those of the best fused silica capillary columns.
Finally, the development and the validation of a coupled electro-thermal Finite Element Model suited for both steady-state and transient analysis of the micro-devices has been described, and subsequently implemented with a fluidic part to investigate devices behaviour in presence of a gas flowing with certain volumetric flow rates.
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Cozzani, Enrico <1977>. "Modeling, design and experimental characterization of Micro-Electro-Mechanical-Systems for gas chromatographic applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3669/.
Full textAbstract:
Design parameters, process flows, electro-thermal-fluidic simulations and experimental characterizations of Micro-Electro-Mechanical-Systems (MEMS) suited for gas-chromatographic (GC) applications are presented and thoroughly described in this thesis, whose topic belongs to the research activities the Institute for Microelectronics and Microsystems (IMM)-Bologna is involved since several years, i.e. the development of micro-systems for chemical analysis, based on silicon micro-machining techniques and able to perform analysis of complex gaseous mixtures, especially in the field of environmental monitoring.
In this regard, attention has been focused on the development of micro-fabricated devices to be employed in a portable mini-GC system for the analysis of aromatic Volatile Organic Compounds (VOC) like Benzene, Toluene, Ethyl-benzene and Xylene (BTEX), i.e. chemical compounds which can significantly affect environment and human health because of their demonstrated carcinogenicity (benzene) or toxicity (toluene, xylene) even at parts per billion (ppb) concentrations.
The most significant results achieved through the laboratory functional characterization of the mini-GC system have been reported, together with in-field analysis results carried out in a station of the Bologna air monitoring network and compared with those provided by a commercial GC system.
The development of more advanced prototypes of micro-fabricated devices specifically suited for FAST-GC have been also presented (silicon capillary columns, Ultra-Low-Power (ULP) Metal OXide (MOX) sensor, Thermal Conductivity Detector (TCD)), together with the technological processes for their fabrication.
The experimentally demonstrated very high sensitivity of ULP-MOX sensors to VOCs, coupled with the extremely low power consumption, makes the developed ULP-MOX sensor the most performing metal oxide sensor reported up to now in literature, while preliminary test results proved that the developed silicon capillary columns are capable of performances comparable to those of the best fused silica capillary columns.
Finally, the development and the validation of a coupled electro-thermal Finite Element Model suited for both steady-state and transient analysis of the micro-devices has been described, and subsequently implemented with a fluidic part to investigate devices behaviour in presence of a gas flowing with certain volumetric flow rates.
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Li, Zhaoyi, and n/a. "Analysis and Design of Virtual Reality Visualization for a Micro Electro Mechanical Systems (MEMS) CAD Tool." Griffith University. School of Information and Communication Technology, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20060731.121340.
Full textAbstract:
Since the proliferation of CAD tools, visualizations have gained importance.. They provide invaluable visual feedback at the time of design, regardless whether it is fbi civil engineering or electronic circuit design-layout. Typically dynamic visualizations are produced in a two phase process: the calculation of positions and rendering of the image and its presentation as an animated video clip. This is a slow process that is unsuitable fbr interactive CAD visualizations, because the former two require finite element analysis Faster hardware eases the problem, but does not overcome it, because the algorithms are still too slow. Our MEMS CAD project works towards methods and techniques that are suitable for interactive design, with faster methods. The purpose of this PhD thesis is to contribute to the design of an interactive virtual prototyping of Micro Electro Mechanical Systems (MEMS) This research comprises the analysis of the visualization techniques that are appropriate for these tasks and identifying the difficulties that need to be overcome to be able to offer a MEMS design engineer a meaningful and interactive CAD design environment Such a VR-CAD system is being built in our research group with many participants in the team. Two particular problems are being addressed by presenting algorithms for truthful VR visualization methods: one is for displaying objects that are different in size on the computer screen. The other is modelling unsynchronized motion dynamics, that is different objects moving simultaneously at very high and vety low speed, by proposing stroboscopic simulation to present their dynamics on the screen They require specific size scaling and time scaling and filtering. It is these issues and challenges which make the design of a MEMS CAD tool different from other CAD tools. In the thesis I present algorithms for displaying animated virtual reality for MEMS virtual prototyping in a physically truthful way by using the simulated stroboscopic illumination to filter animated images to make it possible to show unsynchronized motion.. A scaling method was used to show or hide objects which cannot be shown simultaneously on the computer screen because of their large difference in size. The visualization of objects being designed and their animations is done with much consideration of visual perception and computer capability, which is rising attention, but not too often mentioned in the visualization domain.
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Li, Zhaoyi. "Analysis and Design of Virtual Reality Visualization for a Micro Electro Mechanical Systems (MEMS) CAD Tool." Thesis, Griffith University, 2005. http://hdl.handle.net/10072/366361.
Full textAbstract:
Since the proliferation of CAD tools, visualizations have gained importance.. They provide invaluable visual feedback at the time of design, regardless whether it is fbi civil engineering or electronic circuit design-layout. Typically dynamic visualizations are produced in a two phase process: the calculation of positions and rendering of the image and its presentation as an animated video clip. This is a slow process that is unsuitable fbr interactive CAD visualizations, because the former two require finite element analysis Faster hardware eases the problem, but does not overcome it, because the algorithms are still too slow. Our MEMS CAD project works towards methods and techniques that are suitable for interactive design, with faster methods. The purpose of this PhD thesis is to contribute to the design of an interactive virtual prototyping of Micro Electro Mechanical Systems (MEMS) This research comprises the analysis of the visualization techniques that are appropriate for these tasks and identifying the difficulties that need to be overcome to be able to offer a MEMS design engineer a meaningful and interactive CAD design environment Such a VR-CAD system is being built in our research group with many participants in the team. Two particular problems are being addressed by presenting algorithms for truthful VR visualization methods: one is for displaying objects that are different in size on the computer screen. The other is modelling unsynchronized motion dynamics, that is different objects moving simultaneously at very high and vety low speed, by proposing stroboscopic simulation to present their dynamics on the screen They require specific size scaling and time scaling and filtering. It is these issues and challenges which make the design of a MEMS CAD tool different from other CAD tools. In the thesis I present algorithms for displaying animated virtual reality for MEMS virtual prototyping in a physically truthful way by using the simulated stroboscopic illumination to filter animated images to make it possible to show unsynchronized motion.. A scaling method was used to show or hide objects which cannot be shown simultaneously on the computer screen because of their large difference in size. The visualization of objects being designed and their animations is done with much consideration of visual perception and computer capability, which is rising attention, but not too often mentioned in the visualization domain.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Information and Communication Technology
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Zhang, Bo. "Design, modelling and simulation of a novel micro-electro-mechanical gyroscope with optical readouts." Thesis, Cape Peninsula University of Technology, 2007. http://hdl.handle.net/20.500.11838/1101.
Full textAbstract:
Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2007Micro Electro-Machnical Systems (MEMS) applications are fastest development technology present. MEMS processes leverage mainstream IC technologies to achieve on chip sensor interface and signal processing circuitry, multi-vendor accessibility, short design cycles, more on-chip functions and low cost. MEMS fabrications are based on thin-film surface microstructures, bulk micromaching, and LIGA processes. This thesis centered on developing optical micromaching inertial sensors based on MEMS fabrication technology which incorporates bulk Si into microstructures. Micromachined inertial sensors, consisting of the accelerometers and gyroscopes, are one of the most important types of silicon-based sensors. Microaccelerometers alone have the second largest sales volume after pressure sensors, and it is believed that gyroscopes will soon be mass produced at the similar volumes occupied by traditional gyroscopes. A traditional gyroscope is a device for measuring or maintaining orientation, based on the principle of conservation of angular momentum. The essence of the gyroscope machine is a spinning wheel on an axle. The device, once spinning, tends to resist changes to its orientation due to the angular momentum of the wheel. In physics this phenomenon is also known as gyroscopic inertia or rigidity in space. The applications are limited by the huge volume. MEMS Gyroscopes, which are using the MEMS fabrication technology to minimize the size of gyroscope systems, are of great importance in commercial, medical, automotive and military fields. They can be used in cars for ASS systems, for anti-roll devices and for navigation in tall buildings areas where the GPS system might fail. They can also be used for the navigation of robots in tunnels or pipings, for leading capsules containing medicines or diagnostic equipment in the human body, or as 3-D computer mice. The MEMS gyroscope chips are limited by high precision measurement because of the unprecision electrical readout system. The market is in need for highly accurate, high-G-sustainable inertial measuring units (IMU's). The approach optical sensors have been around for a while now and because of the performance, the mall volume, the simplicity has been popular. However the production cost of optical applications is not satisfaction with consumer. Therefore, the MEMS fabrication technology makes the possibility for the low cost and micro optical devices like light sources, the waveguide, the high thin fiber optical, the micro photodetector, and vary demodulation measurement methods. Optic sensors may be defined as a means through which a measurand interacts with light guided in an optical fiber (an intrinsic sensor) or guided to (and returned from) an interaction region (an extrinsic sensor) by an optical fiber to produce an optical signal related to the parameter of interest. During its over 30 years of history, fiber optic sensor technology has been successfully applied by laboratories and industries worldwide in the detection of a large number of mechanical, thermal, electromagnetic, radiation, chemical, motion, flow and turbulence of fluids, and biomedical parameters. The fiber optic sensors provided advantages over conventional electronic sensors, of survivability in harsh environments, immunity to Electro Magnetic Interference (EMI), light weight, small size, compatibility with optical fiber communication systems, high sensitivity for many measurands, and good potential of multiplexing. In general, the transducers used in these fiber optic sensor systems are either an intensity-modulator or a phase-modulator. The optical interferometers, such as Mach-Zehnder, Michelson, Sagnac and Fabry-Perot interferometers, have become widely accepted as a phase modulator in optical sensors for the ultimate sensitivity to a range of weak signals. According to the light source being used, the interferometric sensors can be simply classified as either a coherence interferometric sensor if a the interferometer is interrogated by a coherent light source, such as a laser or a monochromatic light, or a lowcoherence interferometric sensor when a broadband source a light emitting diode (LED) or a superluminescent diode (SLD), is used. This thesis proposed a novel micro electro-mechanical gyroscope system with optical interferometer readout system and fabricated by MEMS technology, which is an original contribution in design and research on micro opto-electro-mechanical gyroscope systems (MOEMS) to provide the better performances than the current MEMS gyroscope. Fiber optical interferometric sensors have been proved more sensitive, precision than other electrical counterparts at the measurement micro distance. The MOMES gyroscope system design is based on the existing successful MEMS vibratory gyroscope and micro fiber optical interferometer distances sensor, which avoid large size, heavy weight and complex fabrication processes comparing with fiber optical gyroscope using Sagnac effect. The research starts from the fiber optical gyroscope based on Sagnac effect and existing MEMS gyroscopes, then moving to the novel design about MOEMS gyroscope system to discuss the operation principles and the structures. In this thesis, the operation principles, mathematics models and performances simulation of the MOEMS gyroscope are introduced, and the suitable MEMS fabrication processes will be discussed and presented. The first prototype model will be sent and fabricated by the manufacture for the further real time performance testing. There are a lot of inventions, further research and optimize around this novel MOEMS gyroscope chip. In future studying, the research will be putted on integration three axis Gyroscopes in one micro structure by optical sensor multiplexing principles, and the new optical devices like more powerful light source, photosensitive materials etc., and new demodulation processes, which can improve the performance and the interface to co-operate with other inertial sensors and navigation system.
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Conradie, Ewan Hendrik. "Functional photoresist and silicon-on-insulator for micro-electro-mechanical system (MEMS)." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620405.
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Reza, Syed Azer. "Micro-electro-mechanical systems (MEMS) and agile lensing-based modules for communications, sensing and signal processing." Orlando, Fla. : University of Central Florida, 2010. http://purl.fcla.edu/fcla/etd/CFE0003143.
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Reza, Syed. "MICRO-ELECTRO-MECHANICAL SYSTEMS (MEMS) AND AGILE LENSING-BASED MODULES FOR COMMUNICATIONS, SENSING AND SIGNAL PROCESSING." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3463.
Full textAbstract:
This dissertation proposes the use of the emerging Micro-Electro-Mechanical Systems (MEMS) and agile lensing optical device technologies to design novel and powerful signal conditioning and sensing modules for advanced applications in optical communications, physical parameter sensing and RF/optical signal processing. For example, these new module designs have experimentally demonstrated exceptional features such as stable loss broadband operations and high > 60 dB optical dynamic range signal filtering capabilities. The first part of the dissertation describes the design and demonstration of digital MEMS-based signal processing modules for communication systems and sensor networks using the TI DLP (Digital Light Processing) technology. Examples of such modules include optical power splitters, narrowband and broadband variable fiber optical attenuators, spectral shapers and filters. Compared to prior works, these all-digital designs have advantages of repeatability, accuracy, and reliability that are essential for advanced communications and sensor applications. The next part of the dissertation proposes, analyzes and demonstrates the use of analog opto-fluidic agile lensing technology for sensor networks and test and measurement systems. Novel optical module designs for distance sensing, liquid level sensing, three-dimensional object shape sensing and variable photonic delay lines are presented and experimentally demonstrated. Compared to prior art module designs, the proposed analog-mode modules have exceptional performances, particularly for extreme environments (e.g., caustic liquids) where the free-space agile beam-based sensor provide remote non-contact access for physical sensing operations. The dissertation also presents novel modules involving hybrid analog-digital photonic designs that make use of the different optical device technologies to deliver the best features of both analog and digital optical device operations and controls. Digital controls are achieved through the use of the digital MEMS technology and analog controls are realized by employing opto-fluidic agile lensing technology and acousto-optic technology. For example, variable fiber-optic attenuators and spectral filters are proposed using the hybrid design. Compared to prior art module designs, these hybrid designs provide a higher module dynamic range and increased resolution that are critical in various advanced system applications. In summary, the dissertation shows the added power of hybrid optical designs using both the digital and analog photonic signal processing versus just all-digital or all-analog module designs.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
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Maiorca, Felice. "Innovative Electromechanical Transduction Mechanisms for Piezoelectric Energy harvesting from Vibration: Toward Micro and Nano Electro-Mechanical Systems." Doctoral thesis, Università di Catania, 2015. http://hdl.handle.net/10761/3949.
Full textAbstract:
Vibration energy harvesting is one the hottest topics addressed by a big part of the scientific community. A lot of transduction mechanisms have been investigated and designed, based mechanical systems and transduction principles in order to recover energy coming from environmental vibrations. In this work, innovative transduction mechanisms will be described, suitable to harvesting energy from weak random vibrations, to rectifying and multiplying voltages avoiding the use of classic solutions based on diodes. Innovative devices will be introduced, based on nonlinear mechanical systems and piezoelectric transducers; analytical models will be provided and simulation results will be shown. Laboratory prototypes and experiments will be also described. Comparisons between simulations and experiments results will be provided in order to demonstrate the goodness of the proposed approaches. Finally, MEMS technologies suitable with piezoelectric energy harvesting, together with a very simple micro scale prototype, will be introduced as encouraging elements for future miniaturization of the devices.
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Saha, Tanmoy. "Design, fabrication, and complementary metal-oxide- semiconductor (CMOS) integration of micro-electro- mechanical systems (MEMS) humidity sensors." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114228.
Full textAbstract:
The design, microfabrication, and CMOS integration of micro-electro-mechanical systems (MEMS) capacitive humidity sensors are presented in this work. Theoretical analysis and simulations were done to understand how sensor performance can be optimized. While CoventorWare was used for steady-state simulations, a MATLAB simulation model, based on the mathematics of moisture adsorption and diffusion, was developed for dynamic simulations. The sensors were fabricated using a process flow that has a low thermal budget (≤ 300 ○C), as well as material and chemical compatibility with IC fabrication, allowing it to support monolithic integration with CMOS circuitry for system-on-chip (SoC) designs. The fabricated sensors were tested using both deliquescent calibration salts and a humidity / temperature chamber, providing results that were used to compare the performance of various sensor designs. These experimental results, along with the simulation results, were used to devise and justify a design methodology for MEMS capacitive relative humidity sensors. The sensors showed high sensitivity over a large dynamic range, response times as fast as 1.5 seconds, and excellent long term drift as low as 0.1 %RH/year. The humidity sensors were fabricated on top of CMOS dies (TIA - transimpedance amplifier) obtained from Texas Instruments to demonstrate the capability of full monolithic integration of the MEMS sensors and IC. A very convenient and versatile methodology was reported and used for integrating the MEMS sensors above IC dies of any size. Test results show that the performance of the TIA is unaffected by the integration, while the MEMS sensors grown on top of the TIA are fully functional, thereby validating the integration procedure used and the IC-compatibility of the MEMS humidity sensor process flow.La conception, le microfabrication, et l'intégration de CMOS des sondes capacitives micro-électro-mécaniques d'humidité des systèmes (MEMS) sont présentés dans ce travail. L'analyse et les simulations théoriques ont été faites pour comprendre comment l'exécution de sonde peut être optimisée. Tandis que CoventorWare était employé pour des simulations équilibrées, un modèle de simulation de MATLAB, basé sur les mathématiques de l'adsorption et de la diffusion d'humidité, a été développé pour des simulations dynamiques. Les sondes ont été fabriquées en utilisant un écoulement de processus qui a un bas budget thermique (○C de ≤ 300), comme la compatibilité de matériel et de produit chimique avec la fabrication d'IC, lui permettant de soutenir l'intégration monolithique avec des circuits de CMOS pour des conceptions du système-sur-puce (SoC). Les sondes fabriquées ont été examinées en utilisant les deux sels déliquescents de calibrage et une chambre d'humidité/température, fournissant les résultats qui ont été employés pour comparer l'exécution de la diverse sonde conçoit. Ces résultats expérimentaux, avec les résultats de simulation, ont été employés pour concevoir et justifier une méthodologie de conception pour les sondes capacitives d'humidité relative de MEMS. Les sondes montrées la sensibilité élevée au-dessus d'une gamme dynamique étendue, des temps de réponse plus rapidement que 1.5 seconde, et d'une excellente dérive à long terme aussi basse que 0.1 % RH/year. Les sondes d'humidité ont été fabriquées sur les matrices de CMOS (TIA - amplificateur de transimpedance) obtenues à partir de Texas Instruments pour démontrer les possibilités de la pleine intégration monolithique des sondes et de l'IC de MEMS. Une méthodologie très commode et souple a été rapportée et employée pour intégrer les sondes de MEMS au-dessus des matrices d'IC de n'importe quelle taille. Les résultats d'essai prouvent que l'exécution du TIA est inchangée par l'intégration, alors que les sondes de MEMS développées sur le TIA sont entièrement fonctionnelles, validant de ce fait le procédé d'intégration utilisé et l'IC-compatibilité de l'écoulement de processus de sonde d'humidité de MEMS.
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Villa, Victor Fidel. "EVALUATION OF DESIGN TOOLS FOR THE MICRO-RAM AIR TURBINE." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1446.
Full textAbstract:
The development and evaluation of the design of a Micro-Ram Air Turbine (µRAT), a device being developed to provide power for an autonomous boundary layer measurement system, has been undertaken. The design tools consist of a rotor model and a generator model. The primary focus was on developing and evaluating the generator model for the prediction of generator brake power and output electrical power with and without rectification as a function of shaft speed and electrical load, with only basic manufacturer specifications given as inputs. A series of motored generator evaluation test were conducted at speeds ranging from 9,000 to 25,000 rpm for loads varying between 1 and 3.02 Ohms with output power of up to 80 Watts. Results demonstrated that predicted generated power was at or below 3% error when compared to measured results with about 1% uncertainty. A rotor model was also developed using basic blade element theory. This model neglected induced flow effects and was therefore expected to over predict rotor torque and power. A second rotor model that includes induced flow effects, the open source program X-Rotor, was also used to predict rotor power and for comparison to the blade element rotor model results. Both rotor models were evaluated through wind tunnel validation tests conducted on a turbine generator with two different 3.25 in diameter rotors, rotor-1 (untwisted blades) and rotor-2 (twisted blades). Wind tunnel validation test airspeeds varied between 71-110 mph with electrical loads ranging from 1-20 ohms. Results indicated power predictions to be 50-75% higher for the blade element model and 20-30% for X-Rotor results. The blade element rotor model was modified by applying the Prandtl tip-loss factor to approximately account for the induced flow effects; this addition brought predictions much closer to X-Rotor results. Based on the motor-driven generator test results, it is believed that most of the discrepancy in baseline rotor/generator validation test between predicted and observed power generated is due to inaccuracy in the rotor performance modelling with likely contributors to error being induced flow effects, crude section lift/drag modelling, and aero-elastic deformation. It is concluded that the proposed generator model is sufficient although direct torque measurements may be desired and further development of the µRAT design tools should focus on an improved rotor performance model.
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Kifle, Fiseha Teweldebrhan. "Modeling, fabrication and characterization of RF mems–based inductors and thin–film bulk acoustic resonators." Thesis, IIT Delhi, 2016. http://localhost:8080/iit/handle/2074/7006.
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Melli, Mauro. "Mechanical resonating devices and their applications in biomolecular studies." Doctoral thesis, SISSA, 2010. http://hdl.handle.net/20.500.11767/4646.
Full textAbstract:
To introduce the reader in the subjects of the thesis, Chapter 1 provides an overview on the
different aspects of the mechanical sensors. After a brief introduction to NEMS/MEMS, the
different approaches of mechanical sensing are provided and the main actuation and detection
schemes are described. The chapter ends with an introduction to microfabrication.
Chapter 2 deals with experimental details. In first paragraph the advantages of using a pillar
instead of common horizontal cantilever are illustrated. Then, the fabrication procedures and the
experimental setup for resonance frequencies measurement are described. The concluding
paragraph illustrates the technique, known as dip and dry, I used for coupling mechanical
detection with biological problems.
In Chapter 3, DNA kinetics of adsorption and hybridization efficiency, measured by means of pillar
approach, are reported.
Chapter 4 gives an overview of the preliminary results of two novel applications of pillar approach.
They are the development of a protein chip technology based on pillars and the second is the
combination of pillars and nanografting, an AFM based nanolithography.
Chapter 5 starts with an introduction about the twin cantilever approach and of the mechanically
induced functionalization. Fabrication procedure is described in the second paragraph. Then the
chemical functionalizations are described and proved. Cleaved surface analyses and the
spectroscopic studies of the mechanically induced functionalization are reported.
In Appendix A there is an overview of the physical models that are used in this thesis.
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Yildirim, Ender. "Development Of Test Structures And Methods For Characterization Of Mems Materials." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606509/index.pdf.
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This study concerns with the testing methods for mechanical characterization at
micron scale. The need for the study arises from the fact that the mechanical
properties of materials at micron scale differ compared to their bulk counterparts,
depending on the microfabrication method involved. Various test structures are
designed according to the criteria specified in this thesis, and tested for this
purpose in micron scale. Static and fatigue properties of the materials are aimed to
be extracted through the tests. Static test structures are analyzed using finite
elements method in order to verify the results.
Test structures were fabricated by deep reactive ion etching of 100 µm thick (111) silicon and electroplating 18 µ
m nickel layer. Performance of the test structures are evaluated based on the results of tests conducted on the devices made of (111) v silicon. According to the results of the tests conducted on (111) silicon structures, elastic modulus is found to be 141 GPa on average. The elastic modulus of electroplated nickel is found to be 155 GPa on average, using the same test structures. It is observed that while the averages of the test results are acceptable, the deviations are very high. This case is related to fabrication faults in general. In addition to the tests, a novel computer script utilizing image processing is also developed and used for determination of the deflections in the test structures.
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Yazicioglu, Refet Firat. "Surface Micromachined Capacitive Accelerometers Using Mems Technology." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1093475/index.pdf.
Full textAbstract:
Micromachined accelerometers have found large attention in recent years due
to their low-cost and small size. There are extensive studies with different
approaches to implement accelerometers with increased performance for a number of
military and industrial applications, such as guidance control of missiles, active
suspension control in automobiles, and various consumer electronics devices. This
thesis reports the development of various capacitive micromachined accelerometers
and various integrated CMOS readout circuits that can be hybrid-connected to
accelerometers to implement low-cost accelerometer systems.
Various micromachined accelerometer prototypes are designed and optimized
with the finite element (FEM) simulation program, COVENTORWARE, considering
a simple 3-mask surface micromachining process, where electroplated nickel is used
as the structural layer. There are 8 different accelerometer prototypes with a total of
65 different structures that are fabricated and tested. These accelerometer structures occupy areas ranging from 0.2 mm2 to 0.9 mm2 and provide sensitivities in the range
of 1-69 fF/g.
Various capacitive readout circuits for micromachined accelerometers are
designed and fabricated using the AMS 0.8 µm n-well CMOS process, including a single-ended and a fully-differential switched-capacitor readout circuits that can operate in both open-loop and close-loop. Using the same process, a buffer circuit with 2.26fF input capacitance is also implemented to be used with micromachined gyroscopes. A single-ended readout circuit is hybrid connected to a fabricated accelerometer to implement an open-loop accelerometer system, which occupies an area less than 1 cm2 and weighs less than 5 gr. The system operation is verified with various tests, which show that the system has a voltage sensitivity of 15.7 mV/g, a nonlinearity of 0.29 %, a noise floor of 487 Hz µ
g , and a bias instability of 13.9 mg, while dissipating less than 20 mW power from a 5 V supply. The system presented in this research is the first accelerometer system developed in Turkey, and this research is a part of the study to implement a national inertial measurement unit composed of low-cost micromachined accelerometers and gyroscopes.
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Torabi, Soroosh. "TORQUE RESPONSE OF THIN-FILM FERROMAGNETIC PRISMS IN UNIFORM MAGNETIC FIELDS AT MACRO AND MICRO SCALES." UKnowledge, 2017. http://uknowledge.uky.edu/me_etds/95.
Full textAbstract:
The non-contact nature of magnetic actuation makes it useful in a variety of microscale applications, from microfluidics and lab-on-a-chip devices to classical MEMS or even microrobotics. Ferromagnetic materials like nickel are particularly attractive, because they can be easily deposited and patterned using traditional lithography-based microscale fabrication methods. However, the response of ferromagnetic materials in a magnetic field can be difficult to predict. When placed in a magnetic field, high magnetization is induced in these ferromagnetic materials, which in turn generates force and/or torque on the ferromagnetic bodies. The magnitude and direction of these forces are highly dependent on the type of material used, the volume and aspect ratio of the ferromagnetic material, as well as the spatial distribution and magnitude of the magnetic field. It is important to understand these complex interactions in order to optimize force and torque generated, particularly given common limitations found in microfabrication, where it is often challenging to deposit large volumes of ferromagnetic material using conventional microdeposition methods, and power availability is also often limited, which in turn limits the ability to generate strong electromagnetic fields for actuation.
This work represents a theoretical analysis and experimental validation in macro scale to determine best practices when designing ferromagnetic actuators for microscale applications. Specifically, the use of nickel thin film prisms actuated in spatially uniform electromagnetic fields. These constraints were chosen because uniform magnetic fields can be readily generated with a simple and inexpensive Helmholtz coil design, and the uniformity makes actuation force independent of location, minimizing the need for spatial precision in devices. Nickel can also be easily deposited using evaporation or sputtering, generally in forms of thin-films.
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Alvarez, Brian Joel. "Design, Fabrication, and Characterization of a Thin-Film Nickel-Titanium Shape Memory Alloy Diaphragm for Use in Micro-Electro-Mechanical Systems." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/609.
Full textAbstract:
Previous work done at Cal Poly has shown that thin-film nickel-titanium (NiTi) can be easily sputtered onto silicon wafers and annealed to create a crystallized shape memory alloy (SMA) film. Initial work on creating devices yielded cantilevers that were highly warped due to thin-film stress created during the sputtering process. The objective of this work was to create a thin-film NiTi SMA device that could be better characterized. A membrane was selected due to the simplicity of fabrication and testing which would also oppose the thin-film stress due to the increase in attachment points to the substrate.
Silicon wafers were etched through the majority of the thickness (~75%) creating square etch pits of varying sizes varying from 1294 µm to 4394 µm. The wafers were then sputtered with an approximate NiTi film of 5 µm followed by a thin chromium film. The chromium film would act as a diffusion barrier and prevent oxygen from diffusing into the NiTi and reacting with the titanium and forming titanium dioxide. These wafers were then annealed in a custom built vacuum annealing chamber at 550 °C for 1 hour with a pressure around 77 kPa. The chromium was then etched away followed by the remaining silicon. This left a thin membrane of shape memory NiTi which was packaged in order for characterization. The devices were glued to an aluminum substrate using polydimethylsiloxane (PDMS) and sealed with a small Tygon tube leading to the sealed chamber.
This packaged device was then able to be pressurized using a nitrogen tank and the resulting NiTi membrane deflection was measured using a profilometer. Due to the differences in elastic moduli of the room temperature phase (martensite) and the high temperature phase (austenite) a difference of deflection was expected. The austenite finish (Af) temperature of bulk NiTi films was found to be around 60 °C so the devices were tested at both room temperature and at 60 °C. After testing seven separate devices of varying sizes, a regression model was used to analyze the final data.
It was found that pressure, membrane size and theoretical versus actual deflection all affected the maximum deflection, but temperature did not. Higher pressures and larger membranes led to higher deflections as membrane deflection models from fundamental principles indicated. Some devices showed inferior performance when compared to the model due to incomplete silicon etching which caused lower deflection due to the much higher modulus of the remaining silicon. Thickness could also limit the amount of deflection measured with a thicker film leading to less deflection, but this is likely not the case due to the high uniformity of the sputtering system. Other devices showed superior performance over the model most likely due to either local delamination or lateral silicon etching. Both these would create a membrane that was larger than expected leading to a higher deflection. Unforutnaly, differential scanning calorimetry (DSC) analysis showed no shape memory behavior on a test wafer which was anneald at 550 ˚C for 1 hour. A design of experiments was conducted in order to find a heat treatment that would anneal the NiTi film and ensure that shape memory behavior could be obtained. An annealing at 650 °C for 1 hour showed a sharper and clearer Af phase transformation at around the target temperature of 60 °C. Annealing a full wafer at this temperature and time also showed that no delamination would occur which has also been linked to nonideal behavior of the NiTi membranes which has also been linked to meaningful behavior of the NiTi membranes.
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xu, weixing. "POLYMER-DERIVED CERAMICS: ELECTRONIC PROPERTIES AND APPLICATION." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4202.
Full textAbstract:
In this work, we studied the electronic behavior of polymer-derived ceramics (PDCs) and applied them for the synthesis of carbon nanotube reinforced ceramic nanocomposites and ceramic MEMS (Micro-Electro-Mechanical Systems) structures. Polymer-derived SiCN ceramics were synthesized by pyrolysis of a liquid polyureasilazane with dicumyl peroxide as thermal initiator. The structural evolution during pyrolysis and post-annealing was studied using FTIR, solid state NMR and Raman. The results revealed that the resultant ceramics consisted of SiCxNx-4 as major building units. These units were connected with each other through C-C/C=C bonds or by shearing N/C. The amount of sp2 free carbon strongly depends on composition and processing condition. Electron paramagnetic resonance (EPR) was used to investigate electronic structure of PDCs; the results revealed that the materials contain unpaired electron centers associated with carbons. Electronic behavior of the SiCN ceramics was studied by measuring their I-V curves, temperature dependence of d.c.-conductivities and impendence. The results revealed that the SiCN ceramics exhibited typical amorphous semiconductor behavior, and their conductivity varied in a large range. The results also revealed that the materials contain more than one phase, which have the different electronic behavior. We explored possibility of using polymer-derived ceramics to make ceramic MEMS for harsh environmental applications with a lithography technique. The cure depth of the polymer precursor was measured as a function of UV intensity and exposure time. The experimental data was compared with the available theoretical model. A few typical SiCN parts were fabricated by lithography technique. We also prepared carbon nanotube reinforced ceramic nanocomposites by using PDC processing. The microstructures of the composites were characterized using SEM and TEM; the mechanical properties were studied characterized using nanoindentation. The significant improvement in mechanical properties was observed for the nanocomposites.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science and Engineering
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Jensen, Brian D. "Identification of Macro- and Micro-Compliant Mechanism Configurations Resulting in Bistable Behavior." BYU ScholarsArchive, 2003. https://scholarsarchive.byu.edu/etd/83.
Full textAbstract:
The purpose of this research is to identify the configurations of several mechanism classes which result in bistable behavior. Bistable mechanisms have use in many applications, such as switches, clasps, closures, hinges, and so on. A powerful method for the design of such mechanisms would allow the realization of working designs much more easily than has been possible in the past. A method for the design of bistable mechanisms is especially needed for micro-electro-mechanical systems (MEMS) because fabrication and material constraints often prevent the use of simple, well-known bistable mechanism configurations. In addition, this knowledge allows designers to take advantage of the many benefits of compliant echanisms, especially their ability to store and release energy in their moving segments. Therefore, an analysis of a variety of mechanism classes has been performed to determine the configurations of compliant segments or rigid-body springs in a mechanism which result in bistable behavior. The analysis revealed a relationship between the placement of compliant segments and the stability characteristics of the mechanism which allows either analysis or synthesis of bistable mechanisms to be performed very easily. Using this knowledge, a method of type synthesis for bistable mechanisms has been developed which allows bistable mechanisms to be easily synthesized. Several design examples have been presented which demonstrate the method. The theory has also been applied to the design of several bistable micromechanisms. In the process of searching for usable designs for micro-bistable mechanisms, a mechanism class was defined, known as "Young" mechanisms, which represent a feasible and useful way of achieving micro-mechanism motion similar to that of any four-bar mechanism. Based on this class, several bistable micro-mechanisms were designed and fabricated. Testing demonstrated the ability of the mechanisms to snap between the two stable states. In addition, the mechanisms showed a high degree of repeatability in their stable positions.
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Akcakoca, Ugur [Verfasser]. "Electromagnetic Modeling of Nanooptical 2-D Photonic Crystal Structures in Resonant Micro-Opto-Electro-Mechanical Systems: Polarization Selectivity and Tunability / Ugur Akcakoca." Kassel : Universitätsbibliothek Kassel, 2018. http://d-nb.info/1167718712/34.
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Kranz, Michael S. "Micro-mechanical sensor for the spectral decomposition of acoustic signals." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39496.
Full textAbstract:
An array of electret-biased frequency-selective resonant microelectromechanical system (MEMS) acoustic sensors was proposed to perform analysis of stress pulses created during an impact between two materials. This analysis allowed classification of the stiffness of the materials involved in the impact without applying post-impact signal processing. Arrays of resonant MEMS sensors provided filtering of the incident stress pulse and subsequent binning of time-domain waveforms into frequency-based spectra. Results indicated that different impact conditions and materials yielded different spectral characteristics. These characteristics, as well as the resulting sensor array responses, are discussed and applied to impact classification. Each individual sensor element in the array was biased by an in situ charged electret film. A microplasma discharge apparatus embedded within the microsensor allowed charging of the electret film after all device fabrication was complete. This enabled electret film integration using high-temperature surface micromachining processes that would typically lead to discharge of traditionally formed electret materials. This also eliminated the traditional wafer-bonding and post-fabrication assembly processes required in conventional electret integration approaches. The microplasma discharge process and resulting electret performance are discussed within the context of the MEMS acoustic sensor array.
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Sadi, Fazle. "Jump parameter estimation with low cost micro-electro-mechanical system sensors and global positioning system for action sports goggles." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/41971.
Full textAbstract:
Algorithms to detect athletic jumps and to determine in real-time performance parameters such as jump air time (AT), horizontal distance, height
and drop, are developed in this work. These algorithms are customized to be implemented onboard action sports goggles developed by Recon Instruments Ltd. These goggles are equipped with low cost micro-electro-mechanical inertial sensors and a single point GPS receiver which feed raw data to the algorithms. The micro-LCD display system in the goggles displays jump statistics to the user wearing the goggles. Two novel methods, namely WMCM (Windowed Mean Canceled Multiplication) and PFAD (Preceding and Following Acceleration Difference), are introduced for jump detection using accelerometer data. Four characteristic points in the resultant acceleration data are selected as the AT defining epochs for a jump. A novel threshold independent, probabilistic method using MADM (Multiple
Attribute Decision Making) and the Closest Peak method are proposed to detect these characteristic points and determine the corresponding AT of a jump. A GPS/INS integration algorithm is developed to determine jump horizontal distance, height and drop. A novel sensor error compensation scheme is developed using sensor fusion and Linear Kalman Filters (LKF). The LKF parameters are varied to address the fluctuating dynamics of the athlete during a jump. The Extended Kalman Filter (EKF) used for GPS/INS integration has an observation vector augmented with sensor error measurements derived from sensor fusion.
The performance of the proposed algorithms was evaluated through experimental field tests. The proposed jump detection algorithm successfully
detected 92% of the jumps performed by a snowboarder wearing the goggles whereas the current Recon algorithm only detects 60%. The AT determination algorithm exhibited an average error of 0.033 s (4.8%) which is well within the accuracy requirement of Recon, ±0.1 s, and betters the current Recon algorithm which has an average error of 0.111 s (8.4%). For determination
of jump horizontal distance, height and drop, the proposed algorithm has an error of 14.34 cm (5.55%), 1.56 cm (38.21%) and 6.71 cm (9.43%)
respectively. The accuracy achieved is deemed to fulfill expectations of both recreational and professional athletes.
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Kim, Tae Young [Verfasser], Thomas [Akademischer Betreuer] Eibert, Thomas [Gutachter] Eibert, and Georg [Gutachter] Fischer. "Radio Frequency Device and System Design Using Radio Frequency Switches Based on Micro Electro Mechanical Systems / Tae Young Kim ; Gutachter: Thomas Eibert, Georg Fischer ; Betreuer: Thomas Eibert." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1167402235/34.
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Kim, Tae Young Verfasser], Thomas [Akademischer Betreuer] [Eibert, Thomas [Gutachter] Eibert, and Georg [Gutachter] Fischer. "Radio Frequency Device and System Design Using Radio Frequency Switches Based on Micro Electro Mechanical Systems / Tae Young Kim ; Gutachter: Thomas Eibert, Georg Fischer ; Betreuer: Thomas Eibert." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1167402235/34.
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MORADI, KAMRAN. "Acoustic Manipulation and Alignment of Particles for Applications in Separation, Micro-Templating, and Device Fabrication." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/1753.
Full textAbstract:
This dissertation studies the manipulation of particles using acoustic stimulation for applications in microfluidics and templating of devices. The term particle is used here to denote any solid, liquid or gaseous material that has properties, which are distinct from the fluid in which it is suspended. Manipulation means to take over the movements of the particles and to position them in specified locations.
Using devices, microfabricated out of silicon, the behavior of particles under the acoustic stimulation was studied with the main purpose of aligning the particles at either low-pressure zones, known as the nodes or high-pressure zones, known as anti-nodes. By aligning particles at the nodes in a flow system, these particles can be focused at the center or walls of a microchannel in order to ultimately separate them. These separations are of high scientific importance, especially in the biomedical domain, since acoustopheresis provides a unique approach to separate based on density and compressibility, unparalleled by other techniques. The study of controlling and aligning the particles in various geometries and configurations was successfully achieved by controlling the acoustic waves.
Apart from their use in flow systems, a stationary suspended-particle device was developed to provide controllable light transmittance based on acoustic stimuli. Using a glass compartment and a carbon-particle suspension in an organic solvent, the device responded to acoustic stimulation by aligning the particles. The alignment of light-absorbing carbon particles afforded an increase in visible light transmittance as high as 84.5%, and it was controlled by adjusting the frequency and amplitude of the acoustic wave. The device also demonstrated alignment memory rendering it energy-efficient. A similar device for suspended-particles in a monomer enabled the development of electrically conductive films. These films were based on networks of conductive particles. Elastomers doped with conductive metal particles were rendered surface conductive at particle loadings as low as 1% by weight using acoustic focusing. The resulting films were flexible and had transparencies exceeding 80% in the visible spectrum (400-800 nm) These films had electrical bulk conductivities exceeding 50 S/cm.