High- $Q$ AlN-on-Silicon Resonators With Annexed Platforms for Portable Integrated VOC Sensing

Aluminum nitride (AlN) thin-film piezoelectric-onsilicon resonators optimized for gravimetric gas sensing are presented in this paper. Sensors with polyisobutylenefunctionalized annexed platforms exhibit a linear sensitivity of -0.09 Hz/ppm to toluene and -0.18 Hz/ppm to xylene. The annexed platform design enables the sensor to maintain a high Q of 3700 in air and low motional resistance of 1.1 kQ during operation, which ensures low-power oscillator interfacing and readout. AlN-on-Si resonators with annexed platforms are suitable for array implementation in environmental sensing microsystems that measure temperature, humidity, and various gases of importance to health and safety.