Sensitive and Selective Photo Acoustic Gas Sensor Suitable for High Volume Manufacturing

Sensitive and selective gas measurements are crucial for a large variety of applications. This paper describes the manufacturing and characterisation of a photo acoustic gas sensor system. The system is based on a pressure sensor element with a sensitivity of 10 muV/V/Pa. 12 prototypes for measuring CO₂ have been characterised. Detection limits ranging from 92 ppm to below 6 ppm CO₂ were obtained, depending on the measurement time and photo acoustic cell design. No cross-sensitivity towards CO, CH₄, or humidity could be observed in any of the sensors. The temperature drift of the uncompensated raw signal of two sensor designs was below 117 ppm CO₂ in the range from 25degC to 50degC.