This work investigates the effect of Bragg’s reflector configuration stages and its material on the performance of flexible FBAR sensor. Bragg’s reflector configuration has been formed with various high and low acoustic Impedance layers such as Mo/SiO₂, W/SiO_2, and W/Al. The detailed investigation of flexible FBAR sensor has been done using 2-D finite element method (FEM) simulations performed on COMSOL Multiphysics software. Acoustic impedance versus frequency and frequency versus quality factor plots were drawn for the detailed investigation of material and number of Bragg’s reflector configuration stages on the performance of the flexible FBAR sensor. The comparative results for various Bragg’s reflector configurations have been summarized and reported. It is reported that spurious modes were present while using even number of stages to form Bragg’s reflector configuration. Thus, to remove spurious harmonic modes odd number of Bragg’s reflector configuration stages are required. The present work also states that W/SiO₂-based Bragg’s reflector configurations are best suited to achieve enhanced performance in terms of enhanced coupling coefficient and figure of merit. This investigation offers new framework for the design of a flexible FBAR sensor with high performance.