A Bio-Inspired Miniature Comb to Sense the Differential Microphone Diaphragm Deflection

A highly innovative miniature silicon comb to sense differential microphone diaphragm has been developed that is highly stable when subjected to various bias voltages [1]. The bio-inspired microphone diaphragm consists of a 1 mm by 2 mm stiffener-reinforced plate fabricated out of phosphorous-doped polysilicon that is supported on a central hinge [2,3,4]. Interdigitated comb fingers are formed around the perimeter at the ends of the diaphragm by reactive ion etching the polysilicon to create the gaps between the two sets of comb fingers. A fabricated prototype device has demonstrated that this design avoids many key limitations of capacitive microphones through use of a unique comb-sensing design and approach. It provides the means for design and construction of highly innovative capacitive microphones with enhanced sensitivity that can be readily and cost-effectively produced via silicon microfabrication techniques [5].