Vibration-Resistant Microphone Based on ALTP

In most microphones, the pressure fluctuations constituting sound are picked up by a membrane, causing it to vibrate mechanically. These vibrations are then converted to an electric signal by one out of several possible mechanisms. This in turn means that acceleration or non-acoustic vibrations of the membrane, caused e.g. by wind or a moving frame of reference, will degrade the recorded signal. If the eigenfrequency of the membrane is excited, any useful signal may even be drowned out entirely.

In the present invention, the substrate of an atomic layer thermopile (ALTP) sensor element is kept at a temperature somewhat above that of the surrounding medium. When an acoustic wave strikes the sensor, the temperature on the exposed side changes slightly, affecting the heat flow through the sensor element, thereby creating a voltage fluctuation due to the transverse Seebeck effect. This unique operating principle renders the ALTP sensor resistant to acceleration, making it immune to structure-borne vibrations or frequency excitations that adversely affect the membrane of a classical microphone.