  This report presents the realization and characterization of a robust
composite resonator i.e. high overtone bulk acoustic wave resonator (HBAR) and
the changes happening to the resonance peaks once it undergoes mass loading
which has got the potential for application in material characterization,
communication system and sensing. Mass loading effect on a HBAR based on
BaxSr1-xTiO3 (BST) have been demonstrated by coating photoresist of various
thicknesses and characterization of resonance modes present in the frequency
spectrum of the resonator. Upon investigation, HBAR proves to be one of the
most promising and robust systems for gravimetric sensing. Burning effect in
the resonances occurs and it shifts significantly according to the amount of
mass loaded (increasing thickness of the photoresist coated) on the resonator
system. Some of the most important parameters like effective coupling
coefficient, spacing of parallel resonance frequency (SPRF) and quality factor
of the resonator and its numerous modes have been investigated meticulously.
