A novel vacuum pressure sensor using a thermoelectric device

Abstract

We present the proof-of-concept of a new vacuum pressure sensor based on a new operating principle. The new sensor is formed by the simple combination of a thermoelectric (TE) module that is contacted at both sides by a bent copper plate. The vacuum pressure is related to the change in the thermal contact resistance that exists between the outer ceramic surfaces of the TE module and the copper plate, since heat transfer through the ceramic/copper interface is found to be influenced by the amount of air present in the interface gaps (vacuum pressure). The variations of the thermal contact resistance produce a change of the TE module voltage when a fixed current is applied to it. By monitoring this voltage simultaneously to the response of a commercial pressure sensor at different vacuum pressures inside a vacuum chamber, a calibration equation was identified, which enables obtaining the vacuum pressure from the voltage signal. Random errors lower than 10% were found in the 0.1 to 250 mbar range, which is the pressure range that the sensor can properly sense. This new device is inexpensive, simple to fabricate and integrate, and benefits from the high stability of TE modules.