This thesis examines the development and testing of a novel 2 DOF (Degrees of Freedom) thermal actuator using Micro Electro Mechanical Systems (MEMS) technology. A out-of-plane displacement measurement technique based on optical focus adjustments is also implemented and tested. In-plane displacement measurement techniques are also compared. Existing MEMS actuator can either move in-plane or out-of-plane but no reported actuators were found to move in a user selectable combination of both domains. The novel actuator fabricated using the PolyMUMPs process is capable of displacements of 5 ?m out-of-plane and 1.5 ?m in-plane. A Finite Element Analysis (FEA) was performed as a proof of concept prior to physical construction. FEA was also used to characterize the actuator. Measuring out-of-plane displacements of MEMS devices is difficult to accomplish using only a standard microscope and camera setup. Methods have included tilting the chip so the vertical motion has a planar component. The most common commercial measurement technique uses interferomery but special expensive equipment is necessary. A method adapted from biological autofocus is proposed in which multiple images (100+) are taken at various focal planes. An algorithm is applied which extracts the most focused image. An out-of-plane displacement measurement can be extracted between two image sets. Results were compared to optical profiler measurements and the results had an average error of 0.47 ?m A comparison of planar displacement measurement methods, which included two variations of both edge detection and pattern matching along with measurements using the optical profiler, was accomplished. Consistent planar displacement results were collected for all techniques except for the simple edge detection.

This thesis describes a finite element analysis (FEA) model of an indirect heating thermal actuator. The heat transfer mechanisms are investigated and the conductive heat transfer is found to be the dominant heat transfer mode. A model simplification method is discussed and used in the analysis to reduce the degrees of freedom and avoid meshing failures. The device is fabricated with the MetalMUMPs process. Measurements of the displacement as a function of the driving voltage are made to verify the FEA model. The results show that the simulation result of the FEA model produced a reasonable agreement with the experimental data. The difference between the FEA result and test result is investigated. A novel thermal actuator with integrated capacitive position sensor is also investigated. This new thermal actuator with an integrated capacitive sensor uses the indirect heating thermal actuator discussed in the first part of the thesis to achieve a new integration method. The displacement of the actuator provided by the sensor enables a feedback control capability. The analytical model, FEA and test results for the capacitive sensor are presented to validate the design concept. The test results show a reasonable agreement with the analytical analysis and the FEA. Finally, a manual displacement tuning application and a PI feedback control application with the designed thermal actuator with integrated capacitive sensor are documented. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-07-03 16:17:02.633

Microgyroscopes find popular applications in modern life, such as, vehicle navigation, inertial positioning, human body motion monitoring, etc. In this study, three unique MEMS gyroscopic sensors were investigated using experimental methods and finite element analysis (FEA) modelling, particularly their modal behaviour. The analytical, simulated and experimental results were compared and the discrepancy between resonant frequencies of the significant mode shapes was discussed. Three microfabricated gyroscopes were investigated: a thermally-actuated in-plane gyroscope, an electrostatically-actuated in-plane gyroscope and an electrostatically-actuated out-of-plane gyroscope. Numerical finite element modal analysis for these three gyroscopes was conducted using COMSOL Multiphysics. The experimental testing was conducted using a microsystem analyzer (MSA-400 PolyTec) with an integrated laser vibrometer. The simulation models predicted that the frequencies for driving and sensing modes were 4.948kHz and 5.459kHz for a thermally-actuated gyroscope, which agreed well with experimentally determined results of 5.98kHz and 6.0kHz respectively. The power requirements of a thermally-actuated gyroscope were 363.39mW to elicit a maximum peak-to-peak displacement of 4.2μm during dynamic operation. Similarly, the simulated frequencies for the driving and sensing modes were 1.170kHz and 1.644kHz for an electrostatically-actuated in-plane gyroscope, which corresponded to experimentally determined resonant frequencies 1.6kHz and 1.9kHz. Simulation for the electrostatically-actuated out-of-plane gyroscope was conducted and the frequencies for the driving and sensing modes were found to be 2.159kHz and 3.298kHz. Due to some fabrication defects, the experimental testing for this microgyroscope was not successful. Some recommendations to improve the design were provided for the future work. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2010-06-02 22:00:52.994

An alternating current electroosmotic micro pumping device has been designed, experimentally tested and theoretically analyzed using an electrohydrodynamic theoretical model applied to a computer simulation model. The device SP-1 is a microelectrode array which uses the principal of AC electroosmosis (EO), ions driven along microelectrode surfaces by coulomb forces produced by tangential electric fields. These ions, when driven, induce a net fluid motion due to viscous drag forces. Three submerged microelectrode wires were deposited on a substrate using microfabrication techniques such that a square spiral geometry was formed. Device SP-1 received asymmetrically applied AC signals creating a travelling wave of potential and resulted in a net fluid flow across the microelectrode array. Microsphere tracer particles were suspended in ethanol to measure the fluid velocity to determine pumping performance and the experimental operating frequency at which maximum fluid velocity is achieved. The experimental results were reviewed and at an AC signal frequency of 125 Hz, device SP-1 was capable of pumping ethanol at a fluid velocity of approximately 270 μm/s. The experimental results were in good agreement with the theoretical predictions produced using the computer simulation model. In addition, the computer simulation model predicted a similar flow profile to those previously predicted and experimentally observed. Overall, novel micropumping device SP-1 was found to produce a net flow comparable to previously tested devices and a computer simulation framework capable of analyzing future micropump design concepts was developed. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2011-04-01 17:12:02.908

No description available.

A MEMS based electrostatic field sensor is presented which uses capacitive interrogation of an electrostatic force deflected microstructure. First the deflection of the sensor’s membrane which is caused by electrostatic force in the presence of electric field is calculated both by simulation and theoretical model and it has been shown that the results of the simulations have acceptable values compared to the theoretical ones. Simulation models have also been designed to improve the vibration of the membrane for measuring the ac electric fields. It has been shown that by adding perforations to the surface of the membrane, it is possible to reduce the air drag force effect on the membrane and still have similar electrostatic force on the membrane. Therefore, it is possible to reduce the damping due to air resistance in membrane movement when measuring ac fields. After successful modeling of the sensor structure, the fabrication process for the sensor has been designed. The electroplating process as the most important fabrication step has been studied in detail prior to starting the fabrication of sensor. The process parameters for electroplating process, such as current amplitudes, duty cycle and frequency have been optimized to get the lowest surface roughness to thickness ratio for the electroplated films. A lithography molding process was developed for the electroplating. Both dc and pulse plated films have been studied to show the role of pulse plating in improving the quality of the electroplated films. It was found during the release process that the electroplated copper interacted with sulfur during plasma etching of silicon. However, the result of the releasing process was very helpful to find the best recipe of releasing and they can be used in next projects.

Approved for public release; distribution unlimited. / Current solar cell technology suffers low efficiencies in the commercial sector and cost prohibitive technology at higher efficiencies. This thesis investigates the possibility of a novel, alternate, avenue for the creation of solar power, which has the potential to be both cost effective and highly efficient. The approach converts solar energy into electrical energy via a MEMS device that utilizes spectrum-insensitive thermal absorption combined with power generation via the piezoelectric effect. The thesis investigates the underlying physics, materials needed, design requirements, computer modeling, optimization, and microfabrication process in the creation of such a device.

This thesis provides analysis and modeling for one of the Micro-Eletro-Mechanical System (MEMS) electrostatic actuator that consists of a micro-plate at the end of a cantilever beam, and introduces different type of MEMS electrostatic actuator; a paddle structure, which is a micro-plate suspended by two cantilever beams on each side. An electrode plate is placed right under the micro-plate to apply an actuation voltage. A step-by-step analysis explains how to obtain each parameter used for the simulations. Static and dynamic models are presented with governing equations for the paddle-shaped MEMS electrostatic actuator. The key findings are that the proposed electrostatic MEMS demodulator architecture taking advantage of the resonance circuit principle not only theoretically work in analytical model, and numerical simulations, but also work in real life. For the Amplitude Modulations (AM) demodulations, simulations with various damping factors are provided, and experimental data are discussed. By measuring the displacement using the phase detector circuit and vibrometer, as a proof of versatility of the demodulation architecture based on the MEMS electrostatic actuator, the results from Frequency Modulations (FM), Amplitude Shift Keying (ASK), and Frequency Shift Keying (FSK) demodulation scheme experiments that are conducted with the physically identical dimensions and configuration are provided. The future plan for further analysis and experiment is discussed at the end.

The objective of this thesis was to develop a fast-response multifunctional MEMS (Micro Electro Mechanical Systems) sensor for the simultaneous measurement of in-cylinder pressure and temperature in an internal combustion (IC) engine. In a representative IC engine, the pressure and temperature can reach up to about 1.6 MPa and 580 °C, respectively, at the time of injection during the compression stroke. At the peak of the combustion process, the pressure and temperature near the cylinder wall can go beyond 6 MPa and 1000 °C, respectively. Failure of current membrane-based MEMS pressure sensors operating at high temperatures is mainly caused by cross-sensitivity to temperature, which affects the pressure readout. In addition, the slow thermal response of temperature sensors used for such a dynamic application makes real-time sensing within a combustion engine very challenging. While numerous approaches have been taken to address these issues, no MEMS sensor has yet been reported that can carry out real-time measurements of in-cylinder pressure and temperature. The operation of the sensor proposed in this Thesis is based on a new non-planar and flexible multifunctional membrane, which responds to both pressure and temperature variations at the same time. The new design draws from standard membrane-based pressure and thermostatic-based temperature MEMS sensing principles to output two capacitance values. A numerical processing scheme uses these values to create a characteristic sensing plot which then serves to decouple the effects of pressure and temperature variations. This sensing scheme eliminates the effect of cross-sensitivity at high temperatures, while providing a short thermal response time. Thermal, mechanical and electrical aspects of the sensor performance were modeled. First, a semi-analytical thermo-mechanical model, based on classic beam theory, was tailored to the shape of the multifunctional membrane to determine the sensor’s response to pressure and temperature loading. ANSYS® software was used to verify this semi-analytical model against finite element simulations. Then the model was then used to calculate the capacitive outputs of the multifunctional MEMS sensor subjected to in-cylinder pressure and temperature loading during a complete cycle of operation of a typical IC engine as well as to optimize the sensor specifications. Several prototypes of the new sensing mechanism fabricated using the PolyMUMPs® foundry process were tested to verify its thermal behavior up to 125 °C. The experiments were performed using a ceramic heater mounted on a probe station with the device connected to a precision LCR-meter for capacitive readouts. Experimental results show good agreement of the temperature response of the sensor with the ANSYS® finite element simulations. Further simulations of the pressure and temperature response of different configurations of the multifunctional MEMS sensor were carried out. The simulations were performed on an array of 4200 multifunctional devices, each featuring a 0.5 µm thick silicon carbide membrane with an area of 25×25 µm2, connected in parallel shows that the optimized sensor system can provide an average sensitivity to pressure of up to 1.55 fF/KPa (over a pressure range of 0.1-6 MPa) and an average sensitivity to temperature of about 4.62 fF/°C (over a temperature range of 160-1000 °C) with a chip area of approximately 4.5 mm2. Assuming that the accompanying electronics can meaningfully measure a minimum capacitance change of 1 fF, this optimized sensor configuration has the potential to sense a minimum pressure change of less than 1 KPa and a minimum temperature change of less than 0.35 °C over the entire working range of the representative IC engine indicated above. In summary, the new developed multifunctional MEMS sensor is capable of measuring temperature and pressure simultaneously. The unique design of the membrane of the sensor minimizes the effect of cross-sensitivity to temperature of current MEMS pressure sensors and promises a short thermal response time. When materials such as silicon carbide are used for its fabrication, the new sensor may be used for real-time measurement of in-cylinder pressure and temperature in IC engines. Furthermore, a systematic optimization process is utilized to arrive at an optimum sensor design based on both geometry and properties of the sensor fabrication materials. This optimization process can also be used to accommodate other sensor configurations depending on the pressure and temperature ranges being targeted.

Resonant microcantilevers are promising transducers for bacteria detection because of their high sensitivities. Surface stress and mass from adsorbates affect the resonant frequency. We developed a novel method for decoupling the frequency contributions of a change in mass and surface stress on a cantilever sensor validated in theoretical, finite element and experimental framework. Bacteria capture was achieved by several different chemical immobilization of T4 phages. The most successful bacteria capturing surface produced bacterial densities of about 11 bacteria/100^m2. The developed theory is then applied to determine captured bacterial mass on the cantilevers. This provides an estimate of the bacteria mass on the cantilever. Two different functionalizations resulted in predicted bacterial densities of 5 bacteria/100^m2 and 3 bacteria/100^m2. Poor densities relative to surface capture experiments is caused by the boundary effects of the cantilever in solution. / Microelectromechanical Systems and Nanosystems