Anodically Bonded Photoacoustic Transducer: An Approach towards Wafer-Level Optical Gas Sensors.

We present a concept for a wafer-level manufactured photoacoustic transducer, suitable to be used in consumer-grade gas sensors. The transducer consists of an anodically bonded two-layer stack of a blank silicon wafer and an 11 µm membrane, which was wet-etched from a borosilicate wafer. The membrane separates two cavities; one of which was hermetically sealed and filled with CO during the anodic bonding and acts as an infrared absorber.