Miniaturized Photoacoustic Carbon Dioxide Sensor with Integrated Temperature Compensation for Room Climate Monitoring

A miniaturized photoacoustic spectroscopic gas sensor for room climate monitoring is presented with the measurement range of 0 –5000 ppm. The sensor consists of an innovative photoacoustic detection unit with an integrated mobile phone microphone as pressure sensor. As IR-source a broadband thermal emitter is used. The emitter is modulated with 13 Hz at a maximum temperature of about 750 °C. An electronic unit with a microcontroller on a 3D-PCB design has been developed. The sensor reaches a resolution better than 50 ppm CO2. A detailed characterization of the setup has been carried out. An integrated temperature compensation is realized to improve the sensor performance under varying environmental conditions. The potential for further miniaturization and the realization as a low-cost mass market sensor is shown.