Advanced Electrostatic Transducers : For Ultra Low-Power Sensing and High Work Density Actuation
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Over the last few decades, various micro-electromechanical (MEMS) transducers utilizing different actuation and sensing mechanisms have been demonstrated and many of them successfully implemented for wide variety of applications. Although conventional sensors and actuators developed based on MEMS technology address most of the applications, this dissertation focuses on exploring novel approaches to improving the performances of such devices. Among the MEMS sensors, MEMS accelerometers are one of the most successfully commercialized devices implemented for various consumers, industrial, military and biomedical applications. In most cases for the MEMS accelerometer, an analog front end is needed for reading, processing, and analog to digital conversion of the sensor output. Typically, the analog front end is responsible for most of the power consumption of the whole sensor. The proposed effort in this dissertation aims at development of a new class of digitally operating MEMS accelerometers allowing significant power reduction by eliminating the need for the analog front-end. Any electrically powered system with mechanical moving parts utilizes actuators converting electrical energy into mechanical motion. Examples of such includes robotic systems, unmanned vehicles, precision positioning systems, optical systems (e.g. cameras and LIDARs), and medical devices. Piezoelectric actuators are the preferred choice for high precision systems with displacements in the microns range. While piezoelectric actuators are highly power efficient and can output large amounts of force, reaching hundreds of microns of displacement, would require a large piezoelectric element, or non-monolithic integration of a levering mechanism trading excess force for much needed displacement. On the other hand, Electrostatic actuators provide similar or better power efficiency as piezoelectrics, while having much softer structures. Arrayed cellular electrostatic actuators enabled by state-of-the-art MEMS technology, offering displacements in the tens to hundreds of microns while being highly power efficient, compact, and lightweight.