Semiconduct or-based Sensors for Sound and Elect ret Pressure

In this paper the theory and experimental results of integrated electret-based silicon sensors for the detection of sound and pressure are presented. A silicon electret microphone for use in hearing-aid microphones is described, with an experimentally determined sensitivity of 19 mV/Pa in the frequency range of 50 Ha to 10 kHz. Also the realization of a pressure sensor, developed for application in catheter-tip blood-pressure measurements, is discussed. This type of electret sensor appeared to have a pressure sensitivity of 1.6 pV/Pa in the required frequency range of 0 to 100 Hz.