Modelling and On-Chip Detector Design for a MEMS Photoacoustic System

In this work, we theoretically investigate the design and functioning of a novel MEMS Photoacoustic sensing (PAS) system with an on-chip piezoelectric cantilever (using Aluminum nitride (AIN)) for non-resonant detection. The system performance and frequency behavior is explained using the fast, accurate, and predictive capabilities of a developed lumped element model and its adaptability to any target gas and system dimensions. For calculation purposes, NH3 is considered as the target gas due to its ubiquitous use in the food and agriculture industry. The toxic behavior makes its leakage detection for sub-ppm concentrations more important. We also present initial simulation results for the performance of a rectangular cantilever and briefly discuss different ways for its sensitivity enhancement. System noise analysis is also presented and the various sources of origin are discussed. The noise spectral densities are approximated using the lumped model and design optimization for noise reduction is also briefly discussed.