Abstract: A surface micromachined microphone with a 230 kHz bandwidth. The structure uses a 2.25 ?m thick, 305 ?m radius polysilicon diaphragm suspended above an 11 ?m gap to form a variable parallel-plate capacitance. The backcavity of the microphone consists of the 11 ?m thick air volume immediately behind the moving diaphragm, and also an extended larger cavity with a radius of 504 ?m. The dynamic frequency response of the sensor in response to electrostatic signals is presented using laser Doppler vibrometry, and indicates a system compliance of 0.4 nm/Pa in the flat-band of the response. The sensor is configured for acoustic signal detection using a charge amplifier configuration, and signal to noise ratio measurements and simulations are presented herein. A resolution of 0.80 mPa/?Hz (32 dB SPL in a 1 Hz bin) is achieved in the flat-band portion of the response extending from 10 kHz to 230 kHz.

Abstract: A method of designing and manufacturing an acoustic sensor having a high degree of directivity is disclosed. The sensor includes a rotatable plate that is attached to a substrate with mounts. In one aspect the mounts are freely rotatable and the torque on the plate is measured using detectors disposed on springs that provide a resistance to rotation of the plate. In another aspect the plate is mounted to the substrate with mounts that torsionally deform during rotation of the plate. These detectors measure the torque on the plate according to the torsional deformation of the mounts. Methods of improving the signal to noise ratio of acoustic sensors having multiple detectors are also disclosed.

Abstract: A method of designing and manufacturing an acoustic sensor having a high degree of directivity is disclosed. The sensor includes a rotatable plate that is attached to a substrate with mounts. In one aspect the mounts are freely rotatable and the torque on the plate is measured using detectors disposed on springs that provide a resistance to rotation of the plate. In another aspect the plate is mounted to the substrate with mounts that torsionally deform during rotation of the plate. These detectors measure the torque on the plate according to the torsional deformation of the mounts. Methods of improving the signal to noise ratio of acoustic sensors having multiple detectors are also disclosed.