A High-Order Membrane Resonator Array For Gravimetric Ammonia Sensing with Sub-Ppm Limit of Detection

This paper reports on a high-order piezoelectric membrane resonator array with isolated backside functionalization reservoirs used as a gravimetric sensing platform for corrosive and non-corrosive gases. The design allows depositing functional material on the backside of membrane resonators without requiring micropatterning tools or exposing vulnerable frontside metal electrodes. To demonstrate the performance of the proposed platform, we showed ammonia (NH3) sensing in air with a sub-ppm limit of detection, in a large range of 1-400ppm. Carboxylic functionalized polyaniline (PANI) film was used as the sensing/functional material, and its reaction dynamics with ammonia were investigated. The sensor shows great agreement with the Freundlich adsorption isotherm in a wide range.