University of Macau / Faculty of Science and Technology / Department of Electromechanical Engineering

Kwok, Yiu-fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 87-89). / Abstracts in English and Chinese. / ABSTRACT --- p.I / ACKNOWLEDGMENTS --- p.II / TABLE OF CONTENT --- p.III / LIST OF FIGURES --- p.V / Chapter 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Motivation of this project --- p.1 / Chapter 1.3 --- Organization --- p.2 / Chapter 2 --- LITERATURE SURVEY --- p.3 / Chapter 2.1 --- Ionic Conducting Polymer Film (ICPF) --- p.3 / Chapter 2.2 --- Electroactive Polymer (EAP) --- p.4 / Chapter 2.3 --- Micro Active Guide Wire Catheter System --- p.5 / Chapter 2.4 --- Space Application - Dust Wiper --- p.6 / Chapter 2.5 --- Micro gripper --- p.8 / Chapter 2.6 --- Summary of literature survey --- p.14 / Chapter 3 --- METAL-POLYMER COMPOSITIONS --- p.15 / Chapter 3.1 --- Introduction --- p.15 / Chapter 3.2 --- Perfluorosulfonic acid polymer (Nafion) --- p.15 / Chapter 3.3 --- Working principle of ICPF --- p.19 / Chapter 3.4 --- Different types of composition --- p.21 / Chapter 3.4.1 --- Chromium-Gold-polymer composite --- p.23 / Chapter 3.4.2 --- Platinum-Gold-polymer composite --- p.25 / Chapter 3.4.3 --- Silver-polymer composite --- p.27 / Chapter 3.4.4 --- Silver/Copper-gold polymer composite --- p.27 / Chapter 3.4.5 --- Gold-polymer composite --- p.28 / Chapter 4 --- ICPF FABRICATION --- p.30 / Chapter 4.1 --- Introduction --- p.30 / Chapter 4.2 --- ICPF fabrication process --- p.31 / Chapter 4.3 --- Surface pre-treatment --- p.33 / Chapter 4.4 --- Gold thin film deposition (Evaporation) --- p.34 / Chapter 4.4.1. --- Filament evaporation --- p.35 / Chapter 4.4.2 --- Electronic-beam evaporation --- p.39 / Chapter 4.4.3 --- Structural analysis of evaporation --- p.40 / Chapter 4.5 --- Chemical electroplating --- p.42 / Chapter 4.5.1. --- Deposition rate calibration --- p.44 / Chapter 5 --- DESIGN AND PACKAGE --- p.46 / Chapter 6 --- LASER MICROMACHINING --- p.49 / Chapter 6.1 --- Introduction to Laser micromachining --- p.49 / Chapter 6.2 --- C02 laser --- p.50 / Chapter 6.3 --- Nd:YAG Laser --- p.51 / Chapter 6.4 --- Laser micromachining of ICPF actuator --- p.52 / Chapter 7 --- EXPERIMENTAL RESULTS AND ANALYSIS --- p.61 / Chapter 7.1 --- Introduction --- p.61 / Chapter 7.2 --- Measurement setup --- p.62 / Chapter 7.3 --- Width test --- p.68 / Chapter 7.4 --- Length test --- p.73 / Chapter 7.5 --- Voltage test --- p.76 / Chapter 8 --- MICRO GRIPPER ACTUATION --- p.79 / Chapter 8.1 --- Development of micro gripper --- p.79 / Chapter 8.2 --- Micro gripper --- p.80 / Chapter 9 --- CONCLUSION --- p.82 / Chapter 10 --- APPENDIX --- p.83 / Chapter 10.1 --- Procedures in using E-beam evaporator --- p.83 / Chapter 10.2 --- Procedures in using Thermo couple evaporator --- p.85 / Chapter 11 --- REFERENCE --- p.87

Micro-Electro-Mechanical Systems (MEMS) have played an important role in modern microelectronics, thermal, mechanical and hybrid systems. MEMS technology is a very promising means that might have a great impact on almost every corner of the society. Although many design methodology of MEMS already exists, not as much attention was given to the synthesis and optimization of MEMS devices. This thesis focuses on the optimization of MEMS actuators and MEMS tunable comb drive capacitors. The optimization is based on changing device geometry to achieve desired output parameter profile. For example in the design of MEMS tunable comb drive capacitors, the output parameter is the capacitance tuning range. Numerical experiments were performed to show the successful implementation of the optimization method.

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2005. / Includes bibliographical references (p. 175-184).

No description available.

Electromagnetic microactuators with permanent magnets have many potential applications such as micro-energy scavengers, microswitches, micromirrors and microfluidics. However, many electromagnetic microactuator designs utilize either external permanent magnet or external coil, which do not allow tight integration to other MEMS components and further miniaturization. Furthermore, all of the available permanent magnet microfabrication technologies have some drawbacks and improvements are required. Thus the integrated monolithic electromagnetic microactuator is investigated in this project. The three main components of the electromagnetic actuator have been investigated separately. A novel microfabrication technology called ???Template printing???for the fabrication of polymer bonded permanent magnet has been investigated and developed. It is based on ???Screen printing??? which has its drawbacks on alignment accuracy and poor line definition. This is eliminated in ???Template printing??? by photolithography of the photoresist template. The shape and location of the permanent magnet is defined by the template. A new approach based on the filling of dry magnetic powder and vacuum impregnation has been developed to form the polymer bonded permanent magnet. This allows the use of short pot-life matrix material and the elimination of homogenous mixing. A monolithic electromagnetic microactuator has been fabricated successfully. It consists of a 2-layer planar copper microcoil, surface micromachined polyimide beam and Strontium ferrite/EPOFIX permanent magnet (diameter of 460 ??m and 30 ??m thickness). Large deflection in excess of 100 ??m at 35 mA driving current and magnetic force of 0.39 ??N/mA have been achieved. It compares favourably with other much larger electromagnetic actuators that have been reported. ???Template printing??? has the potential of being a low temperature batch process for the microfabrication of thick polymer bonded permanent magnets with high magnetic properties and low residual stress. The fabrication consistency and the quality of template printed magnet can be improved in future studies.

Electromagnetic microactuators with permanent magnets have many potential applications such as micro-energy scavengers, microswitches, micromirrors and microfluidics. However, many electromagnetic microactuator designs utilize either external permanent magnet or external coil, which do not allow tight integration to other MEMS components and further miniaturization. Furthermore, all of the available permanent magnet microfabrication technologies have some drawbacks and improvements are required. Thus the integrated monolithic electromagnetic microactuator is investigated in this project. The three main components of the electromagnetic actuator have been investigated separately. A novel microfabrication technology called ???Template printing???for the fabrication of polymer bonded permanent magnet has been investigated and developed. It is based on ???Screen printing??? which has its drawbacks on alignment accuracy and poor line definition. This is eliminated in ???Template printing??? by photolithography of the photoresist template. The shape and location of the permanent magnet is defined by the template. A new approach based on the filling of dry magnetic powder and vacuum impregnation has been developed to form the polymer bonded permanent magnet. This allows the use of short pot-life matrix material and the elimination of homogenous mixing. A monolithic electromagnetic microactuator has been fabricated successfully. It consists of a 2-layer planar copper microcoil, surface micromachined polyimide beam and Strontium ferrite/EPOFIX permanent magnet (diameter of 460 ??m and 30 ??m thickness). Large deflection in excess of 100 ??m at 35 mA driving current and magnetic force of 0.39 ??N/mA have been achieved. It compares favourably with other much larger electromagnetic actuators that have been reported. ???Template printing??? has the potential of being a low temperature batch process for the microfabrication of thick polymer bonded permanent magnets with high magnetic properties and low residual stress. The fabrication consistency and the quality of template printed magnet can be improved in future studies.

Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Allen, Mark; Committee Member: Allen, Sue; Committee Member: Glezer, Ari; Committee Member: Koros, Williams; Committee Member: Prausnitz, Mark. Part of the SMARTech Electronic Thesis and Dissertation Collection.

This dissertation presents the development of electrically-powered, lamination-based microactuators for the realization of large arrays of high impulse and short duration micro-jets with potential applications in the field of micro-electro-mechanical systems (MEMS). Microactuators offer unique control opportunities by converting the input electrical or chemical energy stored in a propellant into useful mechanical energy. This small and precise control obtained can potentially be applied towards aerodynamic control and transdermal drug delivery applications. This thesis discusses the development of both chemical and physical microactuators and characterizes their performance with focus towards the feasibility of using them for a specific application. The development of electrically powered microactuators starts by fabricating an array of radially firing microactuators using lamination-based micro fabrication techniques that potentially enable batch fabrication at low cost. The microactuators developed in this thesis consist of three main parts: a micro chamber in which the propellant is stored; two electrode structures through which electrical energy is supplied to the propellant; and a micro nozzle through which the propellant or released gases from the propellant are expanded as a jet. The fabricated actuators are then integrated with MEMS-process-compatible propellants and optimized to produce rapid ignition of the propellant and generate a fluidic jet. This rapid ignition is achieved either by making the propellant itself conductive, thus, passing an electric current directly through the propellant; or by discharging an arc across the propellant by placing it between two closely spaced electrodes. The first concept is demonstrated with chemical microactuators for the application of projectile maneuvering and the second concept is demonstrated with physical microactuators for transdermal drug delivery application. For both the actuators, the propellant integrated microactuators are characterized for performance in terms of impulse delivered, thrust generated and duration of the jet. The experimentally achieved results are validated by comparing with results from theoretical modeling. Finally, the feasibility of using chemical microactuators for maneuvering the path of a 25 mm projectile spinning at 500 Hz is discussed and the feasibility of applying the physical microactuators for increasing skin's permeability to drug analog molecules is studied.

Single molecule force spectroscopy is an important technique to determine the interaction forces between biomolecules. Atomic force microscopy (AFM) is one of the tools used for this purpose. So far, AFMs usually use cantilevers as the force sensors and piezoelectrics as the actuators which may have some drawbacks in terms of speed and noise. In this research, a micromachined membrane actuator was used in two important types of experiments, namely the single molecule pulling and force-clamp based force spectroscopy. These two methods permit a more direct way of probing the forces of biomolecules, giving a detailed insight into binding potentials, and allowing the detection of discrete unbinding forces. To improve the quality of the experiments there is a need for high force resolution, high time resolution and increase in the throughput. This research focuses on using the combination of AFM and membrane based probe structures that have electrostatic actuation capability. The membrane actuators are characterized for range, dynamics, and noise to illustrate their adequacy for these experiments and to show that the complexity they introduce does not affect the noise level in the system. The control system described in this thesis utilizes the novel membrane actuator structures and integrates it into the current AFM setup. This is a very useful tool which can be implemented on any AFM without changing its mechanical architecture. To perform an experiment, all that is needed is to place the membrane actuator on the AFM stage, under the imagining head, and run the control system, which was implemented using LabVIEW. The system allows the user to maintain a precise and continuous control of the force. This was demonstrated by performing a life time experiment using biomolecules. Moreover, by slightly modifying the control scheme, the system allows us to linearize the membrane motion, which is inherently non-linear. The feasibility of using this control system for a variety of loading rate experiments are also demonstrated.