SGER: Noise Reduction in Micro-machined Acoustic Sensors Using Digital Feedback

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Prop: 0643055PI: Eva WuThe proposed research focuses on the control oriented modeling of a newly developed biomimetic directional microphone, on the design and analysis of performance of a digital feedback damping scheme, and on the implementation and experimental verification of the digitally controlled microphone. The damping scheme will be applied to the microphone that incorporates a highly innovative diaphragm design fabricated through bulk microfabrication techniques, and a novel optical sensing scheme to provide reading of the diaphragm motion. By also incorporating capacitive actuation, the system becomes an ideal platform for feedback control that has the potential to significantly and robustly enhance the performance of the microsensor.Objectives. The primary objective of this research is to develop an active feedback system to damp unwanted resonances in silicon microsensors for detecting sound and vibration. In addition to improving the response in both the frequency and time domains, this research aims to achieve significant benefits in device dynamic range, output signal-to-noise ratio, and tolerance to the device variability due to random factors during its microfabrication and due to varying operating conditions. The commercial applications of the device examined here include high-sensitivity, low-noise hearing aids, and sensing units in acoustic sensor networks, among others.Intellectual merit. This research will lead to significant improvement in microsensortechnology through a synergy of state-of-the-art advances in mechanical sensor design, silicon microfabrication, and digital control system design which incorporates advanced signal processing and digital hardware technology. The methodical robust feedback design that results from this research, provoked by our innovations in actuation and sensing, will be applicable to a class of microelectromechanical sensor systems where certain nonlinear characteristics of transducers have up till now precluded the effective use of feedback.Broader impacts. Along with the benefits the proposed effort will provide the improvements in hearing-aid technology resulting from this research will also lead to great improvement in the participation of the hearing impaired in all aspects of our society. In addition, this research naturally combines traditional mechanical engineering and electrical engineering disciplines, and therefore facilitates our effort to reform curricula that better prepare our students for entering the highly competitive global market.