Parminder Riarh, LT, Canada

Bio-inspired microelectromechanical systems (MEMS) - based sensors are designed to operate at their resonant frequency for applications that find the direction of sound. In prior research, an open-back MEMS sensor encountered left-right ambiguity in sound direction. This ambiguity was resolved using two open-back sensors. This research investigates whether a single closed-back sensor can find the direction of sound without right-left ambiguity. The MEMS sensor configuration employed in this research provides two resonant modes: rocking and bending. The use of closed-back sensors to determine the direction requires coupling of the rocking and bending modes. First, to optimize the sensor design, the source of coupling was determined using COMSOL Multiphysics software. Tests revealed that decreasing the size of the comb finger gap increases the damping. However, wing size is the main source of damping. Based on the test results, optimized sensors were designed and fabricated. The back of the sensor was closed to prevent sound coupling from the back. Measurement of the directional response of the sensor showed that the two wings oscillated with different amplitudes when operated in rocking mode. It was found that the ratio of the sum over the difference of the amplitudes has a sine dependence as opposed to ambiguous cosine dependence. Thus, sine dependence resolved the left-right ambiguity.

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Dec 29, 2018

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