A Non-planar CMUT Array for Automotive Blind Spot Detection

A discretized hyperbolic paraboloid geometry capacitive micromachined ultrasonic transducer (CMUT) array has been designed and fabricated for automotive blind spot monitoring application. The array is designed for a frequency range of 113-167 kHz, beamwidth of 20▒50 with a maximum sidelobe intensity of -6dB. An SOI based fabrication technology has been used for the 5x5 array with 5 sensing surfaces along each x and yaxis and 7 elevation levels. An assembly and packaging technique has been developed to realize the non-planar geometry in a PGA-68 package. Two new analytical models has been developed to more accurately calculate the deflection profile of a thin square membrane and capacitance change due to both external mechanical pressure and the electrostatic pressure due to the bias voltage. The developed models incorporate the effects of bias voltage, external pressure, fringing field capacitance and large deflections. Both the models exhibit excellent accuracy when compared with IntelliSuite FEA results.

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