A flow-sensing velocity microphone

A microphone is described having a sensing element driven by viscous forces due to the fluctuating velocity of the air in a sound field. Unlike typical microphones having pressure-sensing diaphragm, thin microfabricated beams or thin porous plates are used to detect acoustic flow. The structures are designed to maximize the effects of viscosity on their motion. To transduce the motion into an electronic signal, a new capacitive sensing approach is utilized that imposes minimal electrostatic force, enabling the sensor to be highly compliant without being affected by the use of large bias voltages.