High resolution micro-Pirani pressure sensor gauge with transient response processing

A micro-Pirani pressure sensor, which consists of a pressure dependent thermo-resistance gauge, is traditionally exploited using a steady state resistance measurement. Any signal variation occurs over a constant voltage bias due to the initial resistance of the device which affects the sensor´s sensitivity. Our work shows for the first time an experimental investigation of a micro-Pirani gauge based on its dynamic behavior when heated by a current step. Such processing magnifies the pressure dependence of the gauge´s signal by eliminating the initial resistance influences on the measurement. Furthermore, a first order low pass filter step response identification of the experimental transient signal strongly reduces the thermal noise influence on the measurement. The heating step, the recording of the time dependent signal and its post-processing can be easily achieved by a small-size controller. The proposed system provides a substantial enhancement of the micro-Pirani pressure sensor performance.