How to Turn a MEMS Microphone Into a Photoacoustic Sensor: An Experimental Study

In the search of miniaturized, highly sensitive photoacoustic (PA) sensors, MEMS microphones soldered on customized printed circuit boards (PCB) are investigated for their use as gas sensing volume, acoustic resonator and sound transducer at the same time. In combination with an appropriate laser selected for the target gas absorption line, a very compact PA sensor suitable for trace gas sensing is obtained. Here, the resonant phenomena of these novel PA cells were studied. Methane was used to evaluate different microphone and PCB configurations in the audio and ultrasound regime. Different acoustic resonances have been experimentally characterized.