Large scale changes in overtone resonances and resonant peak burning of HBAR with mass loading and its potential for applications

Abstract: 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.