Differential Microphone

This technology provides an acoustic sensing device or directional microphone having greater sensitivity and reduced noise. The directional microphone or acoustic sensor comprises a rigid, one micron thick polysilicon membrane having dimensions of approximately 1 mm×2 mm. The membrane is supported upon its central axis by beams having torsional and transverse stiffness. The total damped area of the microphone is between approximately 1.5 and 2.5×10−6 m2. The distance between centers of the two sides of the device is approximately 10−3 m. The resonant fre-quency in the rotational mode is in a range of between approximately 700 to 1,000 Hz, and the resonant frequency of the translational mode is in the range of between approximately 40,000 and 45,000 Hz. The differential microphone is useful in hearing aids, telecommunica-tions equipment, information technology and military applications.



  • The microphone diaphragm is differential, meaning that it uses changes in air pressure to differentiate as to where a sound is coming from. Thus, the dia-phragm is directional, and can detect changes in sound direction. The microphone detects the loudest noise in its proximity and filters out extraneous noises.
  • The diaphragm is more flexible and sensitive than conventional designs due both to physical design and the use of silicon in fabrication.
  • The microphone diaphragm offers manufacturing improvements, regarding time and cost, since it is made of silicon.


Intellectual Property


U.S. 6,788,796




Binghamton University RB127

Patent Information: