SUMMARY

Microphones are widely used in many applications like cellular phones, hearing aids and acoustic measurement devices. As the size of the microphone diaphragms reduces with the use of microelectromechanical systems (MEMS) technology, traditional capacitive sensing methods used in miniature microphones imposes key limitations on microphone performance. The use of diffraction-based optical detection method alleviates these limitations by providing high displacement detection sensitivity nearly independent of the size and the capacitance of the microphone. This enables novel backplate and diaphragm designs to obtain low noise performance with broad bandwidth. In this study, optical detection method is used with micromachined biomimetic gradient and omnidirectional microphone structures. In these micromachined microphones, the integrated electrostatic port of the sensor is uncoupled from the integrated optical sensing making it available for sensitivity tuning, self characterization, and active control to adjust the device dynamics. The proposed research explores the feasibility of low noise, high bandwidth and high fidelity optical microphones with force feedback, and intensity probes based on these microphones. Initial implementation of force feedback method shows that it is possible to alter the dynamics of the microphones in a desirable manner while achieving directionality and extremely low noise levels. Small size, broad band intensity probes using biomimetic gradient microphones and omnidirectional microphones phase matched with force feedback are investigated in this study. These devices would enable identification and characterization of complex acoustic fields generated by small sources.