Sensitive and Selective Photoacoustic 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 characterization of a photoacoustic gas sensor system. The system is based on a pressure sensor element with a sensitivity of 10 muV/V/Pa. To demonstrate and evaluate the concept, 12 prototypes for measuring CO₂ have been manufactured and characterized. Detection limits ranging from 92 ppm to below 6 ppm CO₂ were obtained with a path length of 10 cm, depending on the measurement time and photoacoustic cell design. Measurements showed no cross-sensitivity towards CO, CH₄, or humidity 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.