This paper represents the design and FEM modeling of solidly mounted film bulk acoustic resonator (SMFBAR) gas sensor, based on ZnO, for Tetrachloroethane (PCE) gas detection. The effect of sensitive polyisobutylene(PIB) layer coating on mass sensitivity has been analyzed along with optimization of the layer thickness. The proposed structure shows good quality factor of 758, at resonance condition, and a coupling coefficient of 7.36% for the piezoelectric layer with 2 μm thickness. SMFBAR sensor was tested for detection of various gases such as, Tetrachloroethane (PCE), Trichloroethylene (TCE), Trichloromethane (TCM) and chloromethane (CM), with PIB layer as the sensing element. A new SMFBAR based detector with enhanced sensitivity of 21 kHz/ppm for detection of Tetrachloroethane (PCE) gas has been reported. FEM Modeling has been done on COMSOL Multiphysics software and a resonant frequency of 1.38 GHz has been observed for ideal environment. The sensor was tested for various concentrations ranging from 100 to 1000 ppm of Tetrachloroethane gas. © 2018 IOP Publishing Ltd.