Surgace Micromachined Dif-ferential Microphone

This invention consists of a microphone that can be fabricated with surface micromachining. In typical micromachined microphones, it is necessary to incorporate a significant volume of air behind the microphone diaphragm in order to prevent the back volume air from impeding the motion of the diaphragm. The air behind the diaphragm acts as a linear spring whose stiffness is inversely proportional to the nominal volume of the air. In order to make this air volume as large as possible, and hence reduce the effective stiffness, a through-hole is normally cut from the backside of the silicon chip. The requirement of this backside hole adds significant complexity and expense to these devices. This invention enables the creation of a microphone that does not require this backside hole. The motion of typical microphone diaphragms results in a fluctuation in the net volume of air in the region behind the diaphragm.



  • The use of a very small backing cavity is possible, thereby obviating the need for creating a backside hole.
  • Lower cost since no secondary machining operation for creating backside holes is necessary


Intellectual Propery:


U.S. 7,992,283; 8,214,999, 8,276,254. KR10-1360104. GE 112007000263




Binghamton University RB229

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