Abstract: A miniature chemical sensor using a thin film acoustic resonator coated with a chemically sensitive sorbent coating. The thin film acoustic resonator has electrodes separated by a thin piezoelectric layer and is supported by a multilayer resonant acoustic isolator. The resonant acoustic isolator has alternating layers of high and low acoustic impedance material, each layer being one quarter acoustic wavelength thick or an odd multiple thereof at the resonant frequency. The resonant acoustic isolator is solidly mounted on a substrate but provides acoustic isolation between the thin film acoustic resonator and the substrate at a resonant frequency.