Lai, Wai Chiu King. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 87-89). / Abstracts in English and Chinese. / LIST OF TABLES --- p.vi / LIST OF FIGURES --- p.vii / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Organization of the thesis --- p.3 / Chapter 2. --- Literature Survey --- p.5 / Chapter 2.1 --- Micro Hinges --- p.5 / Chapter 2.2 --- Assembly --- p.5 / Chapter 2.2.1 --- Manual Lift Up Process --- p.5 / Chapter 2.2.2 --- Assembly by On-substrate Actuators --- p.6 / Chapter 2.2.3 --- Assembly by Surface Tension Force --- p.8 / Chapter 2.2.4 --- Assembly by Thermal Shrinkage --- p.8 / Chapter 2.2.5 --- Assembly by Ultrasonic Triboelectricity --- p.9 / Chapter 2.3 --- Summary of Literature Survey --- p.9 / Chapter 3. --- Design & Analysis --- p.11 / Chapter 3.1 --- Micro-Assembly by Centrifugal Force --- p.11 / Chapter 3.2 --- Micro Mass Platform --- p.12 / Chapter 3.2.1 --- Micro Mirror --- p.12 / Chapter 3.2.2 --- Rotation Sensor --- p.15 / Chapter 3.3 --- Fabrication of Micro Structures --- p.16 / Chapter 3.4 --- Force Analysis --- p.18 / Chapter 3.4.1 --- Centrifugal Force --- p.18 / Chapter 3.4.2 --- Van der Waals Forces --- p.20 / Chapter 3.4.3 --- Capillary Force - (1st model) --- p.22 / Chapter 3.4.4 --- Capillary Force - (2nd model) --- p.23 / Chapter 3.4.5 --- Casimir Force --- p.26 / Chapter 3.4.6 --- Spring force of the beam --- p.27 / Chapter 3.4.7 --- Comparison of Forces --- p.28 / Chapter 3.4.8 --- Stress on Polysilicon --- p.30 / Chapter 4. --- Surface Force Measurement --- p.32 / Chapter 4.1 --- Experimental Setup --- p.33 / Chapter 4.2 --- Experimental Result --- p.34 / Chapter 4.2.1 --- Control Experiment of Rotation Sensor --- p.34 / Chapter 4.2.2 --- Freed-state and Snap-down-state --- p.35 / Chapter 4.2.3 --- Summary of the Experimental Data --- p.36 / Chapter 4.3 --- Comparison between Modelled Results and Experimental Data --- p.42 / Chapter 5. --- Assembly Experiment --- p.45 / Chapter 5.1 --- Experimental Setup --- p.45 / Chapter 5.2 --- Experimental Results --- p.46 / Chapter 5.3 --- Comparison among different chips --- p.52 / Chapter 6. --- Assembly Experiment (Double Chips) --- p.57 / Chapter 6.1 --- Experimental Setup --- p.57 / Chapter 6.2 --- Experimental Results --- p.58 / Chapter 6.2.1 --- Surface Profile measurement --- p.58 / Chapter 6.2.2 --- Summary of the surface profile measurement --- p.68 / Chapter 6.2.3 --- Assembly Results --- p.69 / Chapter 7. --- Assembly Experiment (Monitoring System in MUMPs46) --- p.72 / Chapter 7.1 --- Experimental Setup --- p.72 / Chapter 7.2 --- Experimental Results --- p.74 / Chapter 8. --- Other tested micro structures --- p.80 / Chapter 9. --- Conclusion --- p.82 / Chapter 10. --- Future Work --- p.83 / Chapter A. --- Appendix --- p.84 / Bibliography --- p.87

No description available.

by Lam Hiu-fung. / "Augustr 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 178-182). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Xiao, Peng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 76-78). / Abstracts in English and Chinese. / ABSTRACT --- p.i / 摘要 --- p.iii / ACKNOWLEDGEMENTS --- p.iv / TABLE OF CONTENTS --- p.vi / LIST OF FIGURES --- p.viii / LIST OF TABLES --- p.xi / Chapter CHAPTER ONE --- INTRODUCTION --- p.1 / Chapter 1.1 --- The Thermal Characteristic of the CNT Heater --- p.1 / Chapter 1.2 --- CNT-Based Micro Bubble Generation in a Static Droplet of Water --- p.2 / Chapter 1.3 --- CNT-Based Micro Bubble Transportation in a Micro Channel --- p.4 / Chapter 1.4 --- CNT-Based Micro Bubble Stimulation by Pulsed Current --- p.4 / Chapter CHAPTER TWO --- THE THERMAL CHARACTERISTICS OF CARBON NANOTUBES --- p.6 / Chapter 2.1 --- Temperature Coefficient of Resistance (TCR) of Our Typical CNT Heater --- p.7 / Chapter 2.2 --- The Humidity Coefficient of the Resistance (HCR) for Our Typical CNT Heater --- p.13 / Chapter 2.3 --- The Conclusion of the CNT Heater's Thermal and Humidity Characteristics --- p.18 / Chapter CHAPTER THREE --- MICRO BUBBLE GENERATION WITH MICRO WATT POWER USING CARBON NANOTUBE HEATING ELEMENTS --- p.19 / Chapter 3.1 --- Micro Electrode Fabrication --- p.19 / Chapter 3.1.1 --- Methods for Metal Electrode Fabrication --- p.20 / Chapter 3.1.2 --- Advantages and Disadvantages of Two Micro Fabrication Methods --- p.22 / Chapter 3.1.3 --- The Fabrication of Micro Electrodes for Our CNT Heater --- p.24 / Chapter 3.1.4 --- The Mask Design for Metal Electrode Fabrication --- p.26 / Chapter 3.2 --- The Micro Bubble Generation Experimental Procedure --- p.28 / Chapter 3.2.1 --- Initial Analysis of the Experimental Device --- p.28 / Chapter 3.3 --- Theoretical Analysis of Bubble Generation Temperature on the CNT Heater --- p.31 / Chapter 3.3 --- The Analysis of the Micro Bubble Generation Experimental Results --- p.35 / Chapter 3.4 --- The Conclusion of Bubble Generation in a Static Droplet of Water --- p.44 / Chapter CHAPTER FOUR --- CARBON NANOTUBE-BASED MICRO BUBBLE GENERATION IN A MICRO CHANNEL WITH DYNAMIC FLUID --- p.45 / Chapter 4.1 --- Micro Channel Fabrication --- p.46 / Chapter 4.1.1 --- Rapid Prototyping --- p.46 / Chapter 4.1.2 --- PDMS Moulding --- p.47 / Chapter 4.1.3 --- Irreversible Sealing --- p.49 / Chapter 4.1.4 --- Mask Design --- p.50 / Chapter 4.2 --- Experimental Setup --- p.51 / Chapter 4.3 --- Experimental Procedure --- p.53 / Chapter 4.4 --- Experimental Results --- p.55 / Chapter 4.5 --- Conclusion for Bubble Generation in the Micro Channel with Dynamic Fluid --- p.59 / Chapter CHAPTER FIVE --- CNT-BASED MICRO BUBBLE STIMULATION BY PULSED CURRENT --- p.60 / Chapter 5.1 --- Attempt to Control the Micro Bubble Diameter --- p.61 / Chapter 5.2 --- The Pulsed Current for Micro Bubble Departure in the Micro Channel --- p.63 / Chapter 5.2.1 --- Manual Pulsed Current Stimulation for Micro Bubble Departure in the Micro Channel --- p.64 / Chapter 5.2.2 --- The Pulsed Current Circuit for Micro Bubble Departure in the Micro Channel --- p.67 / Chapter CHAPTER SIX --- FUTURE WORK AND SUMMARY --- p.70 / Chapter 6.1 --- Future Work for Micro Bubble Generation Projects --- p.70 / Chapter 6.1.1 --- The CNT-Based Micro Bubble Generation with Various Values of Input Current --- p.70 / Chapter 6.1.2 --- The CNT Heater in the Zig-Zag Micro Channel --- p.71 / Chapter 6.1.3 --- Summary --- p.72 / APPENDIX A --- p.73 / Fabrication Process --- p.73 / Chapter I. --- Micro Electrode Fabrication --- p.73 / Chapter II. --- Micro Channel Fabrication --- p.75 / BIBLIOGRAPHY --- p.76

Micromanufacturing consists of processes for producing structures, devices or systems with feature sizes measured in micrometers. Micromanufacturing began in the mid-1960's with microelectronics fabrication technology. In the 1980's, Micro-Electro-Mechanical Systems (MEMS) began to be developed, in which electrical and mechanical subsystems were integrated at small scales. More recently, Microtechnology-based Energy and Chemical Systems (MECS) have been developed that have led to improved heat and mass transfer in energy and chemical systems. At Oregon State University, new methods to fabricate MECS have been developed. One of the new methods involves microlamination--bonding thin strips of different materials together. This method has generated a high volume and low-cost approach to the production of high-aspect-ratio (height-to-width) structures. Past efforts to make microfloat valves using microlamination methods resulted in an 11:1 diodicity ratio. It was hypothesized that the valve had a ridge of redeposited material around the valve seat caused by the condensation and deposition of ablation ejecta during laser machining. The contribution of this thesis is the creation of a microfloat valve using an Electrochemical Micromachining (EMM) method. EMM methods are known to produce smooth surfaces, free of burrs or any other types of aspirates. Therefore, it was hypothesized that float valves made with EMM methods would improve valve performance. Four steps were involved in the creation of the microfloat valve: lamina formation, laminae registration, laminae bonding and component dissociation. A total of 9 laminae-some of which were made with 304 stainless steel 76.2 ��m thick, others of which were made with 50.8 ��m thick polyimide-made up the microfloat valve. Photolithography and EMM were used to form the lamina. Even though the laminae created by EMM were smaller in size than desired, the machined areas did not have redeposited material, and some areas had straight walls. In laminae registration, a two edge registration method was used. In the laminae bonding step, laminae were bonded by the adhesive method at 248��C under 135 kPa pressure for 13.5 minutes. In the component dissociation step, a capacitor dissociation method that was designed at OSU was used. Upon performance testing, the average diodicity ratio for the EMM valve was 12.45 over the range 0 kPa-450 kPa, indicating improved performance when compared to the Laser Ablation valve-which had an average 11.17 over the range 0 kPa-100 kPa. Microscope examination of valves revealed that statistically significant improvement in valve performance would require refinement of component dissociation methods. / Graduation date: 2000

Since the dawn of the computer age, there has been a push to create miniature devices. These devices were initially integrated circuit (IC) devices to perform calculations for computers. As the technology progressed, the scope of the devices diverged to included microelectromechanical (MEMS) devices, meaning that the devices perform mechanical movements via electrical actuation. More recently, a new generation of devices has evolved called microtechnology-based energy and chemical systems (MECS). MECS may employ MEMS technology, however the systems are not designed to produce only mechanical movement. MECS deal with heat and mass transfer, the basic processes used in energy, chemical and biological systems, in the mesoscale realm. Mesoscale devices range from the size of a sugar cube to the size of a human fist. The possibilities of MECS have not been realized. Heating and cooling systems, chemical mixing/distribution, and locking systems are all potential applications. The devices require: 1) revolutionary design, accounting for the scaling effects on device performance; 2) new fabrication technologies for the creation of these designs; and 3) good material properties for mechanical and chemical interactions. Fabrication requirements for MECS are different than for MEMS in that MECS generally require non-silicon metals. Metal microlamination (MML) has been introduced as a general practice for meeting the fabrication requirements for MECS. Prior MML fabrication methods have emphasized the use of diffusion bonding, soldering, or brazing techniques. This thesis will introduce: 1) a novel microflapper valve design fabricated in mild steel using a novel microprojection welding technique; 2) a novel microfloat valve design fabricated in mild steel using a novel capacitive dissociation process for creating free floating geometries. The devices are characterized by comparing actual flow rates to theoretical flow rates of equivalent orifice sizes. Preliminary results show that the microfloat valve achieved an average diodicity (free flow versus leakage rate) ratio of 11.19, while the microflapper valve achieved an average diodicity ratio of 4.08. The theoretical orifice sizes of the microfloat and microflapper valves are 0.629 mm and 0.611 mm respectively. These results suggest that the float valve is the superior design. / Graduation date: 1999

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references. Also available in electronic version.

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2005. / Includes bibliographical references (p. 47-50).

Microelectromechanical systems (MEMS) devices have been increasing in popularity for radio frequency (RF) and microwave communication systems due to the ability of MEMS devices to improve the performance of these circuits and systems. This interdisciplinary field combines the aspects of lithographic fabrication, mechanics, materials science, and RF/microwave circuit technology to produce moving structures with feature dimensions on the micron scale (micro structures). MEMS technology has been used to improve switches, varactors, and inductors to name a few specific examples. Most MEMS devices have been fabricated using planar micro fabrication techniques that are similar to current IC fabrication techniques. These techniques limit the thickness of individual layers to a few microns, and restrict the structures to have planar and not vertical features. <p> One micro fabrication technology that has not seen much application to microwave MEMS devices is LIGA, a German acronym for X-ray lithography, electroforming, and moulding. LIGA uses X-ray lithography to produce very tall structures (hundreds of microns) with excellent structural quality, and with lateral feature sizes smaller than a micron. These unique properties have led to an increased interest in LIGA for the development of high performance microwave devices, particularily as operating frequencies increase and physical device size decreases. Existing work using LIGA for microwave devices has concentrated on statically operating structures such as transmission lines, filters, and couplers. This research uses these unique fabrication capabilities to develop dynamically operating microwave devices with high frequency performance. <p>This thesis documents the design, simulation, fabrication, and testing of MEMS variable capacitors (varactors), that are suitable for fabrication using the LIGA process. Variable capacitors can be found in systems such as voltage-controlled oscillators, filters, impedance matching networks and phase shifters. Important figures-of-merit for these devices include quality factor (Q), tuning range, and self-resonant frequency. The simulation results suggest that LIGA-MEMS variable capacitors are capable of high Q performance at upper microwave frequencies. Q-factors as large as 356 with a nickel device layer and 635 with a copper device layer, at operational frequency, have been simulated. The results indicate that self-resonant frequencies as large as 45 GHz are possible, with the ability to select the tuning range depending on the requirements of the application. Selected capacitors were fabricated with a shorter metal height for an initial fabrication attempt. Test results show a Q-factor of 175 and a nominal capacitance of 0.94 pF at 1 GHz. The devices could not be actuated as some seed layer metal remained beneath the cantilevers and further etching is required. As such, LIGA fabrication is shown to be a very promising technology for various dynamically operating microwave MEMS devices.

Multilayer microwave circuit processing technology is essential in developing more compact radio frequency (RF) electronically scanned arrays (ESAs) for next generation radar systems. ESAs are typically realized using the hybrid connection of four discrete components: RF manifold, phase shifters or Butler matrices, antennas and T/R modules. The hybrid connection of these components increases the system size, packaging cost and introduces parasitic effects that lead to higher losses. In order to eliminate these drawbacks, there is a need to integrate these components on the same substrate, forming a monolithic phased array. RF MEMS technology enables the monolithic integration of the ESA components into one highly integrated multifunctional module, thereby enhancing ESA designs by significantly reducing size, fabrication cost and interconnection losses. A novel capacitive dual-warped beam shunt MEMS switch is presented that utilizes warped beams to enhance its RF performance. This switch exhibits an off-to-on capacitive ratio of almost 170, isolation better than 40dB, switching speeds as low as 6μs without the need for thin dielectrics or high dielectric constant materials. These MEMS switches are implemented into single pole three throw (SP3T) and single pole four throw (SP4T) configurations. A novel 3-bit finite ground coplanar waveguide switched delay line MEMS phase shifter is developed with four cascaded SP3T dual-warped beam capacitive switches to achieve low-loss performance and simplify ESA design. The fabricated prototype unit exhibits an insertion loss of 2.5∓0.2dB with a phase error of ∓6°. Moreover, a compact 4 x 4 Butler matrix switchable with the use of a MEMS SP4T switch is investigated as an alternative passive beamforming method. The overall beam-switching network is monolithically integrated within a real-estate area of 0.49cm2. This technique provides a unique approach to fabricate the entire beamforming network monolithically. An 8-mask fabrication process is developed that monolithically integrates the MEMS phase shifter and RF combining network on one substrate. The wafer-scale integrated ESA prototype unit has an area of 2.2cm2. It serves as the basic building block to construct larger scanning array modules and introduces a new level of functionality previously achieved only by the use of larger, heavier and expensive systems