Miniaturized thermal acoustic gas sensor based on a CMOS microhotplate and MEMS microphone.

We present a miniaturised thermal acoustic gas sensor, fabricated using a CMOS microhotplate and MEMS microphone. The sensing mechanism is based on the detection of changes in the thermal acoustic conversion efficiency which is dependent on the physical properties of the gas. An active sensing element, consisting of a MEMS microphone, is used to detect the target gas while a reference element is used for acoustic noise compensation. Compared to current photoacoustic gas sensors, our sensor requires neither the use of gas-encapsulated microphones, nor that of optical filters. In addition, it has all the benefits of CMOS technology, including production scalability, low cost and miniaturization. Here we demonstrate its application for CO[Formula: see text] gas detection. The sensor could be used for gas leak detection, for example, in an industrial plant.We acknowledge funding from EPSRC grants EP/S031847/1, EP/R022534/1, Alan Turing Institute Award TU/B/ 000096 under EPSRC Grant EP/N510129/1, and Royal Society Equipment Grant RG170136