A novel method of studying the micro-contact using surface acoustic wave sensor

Abstract

Purpose This paper aims to investigate the response behavior of the surface acoustic wave (SAW) sensor under the loading of micro-particles and to evaluate the feasibility of using the SAW sensor to study the micro-contact of the particle–plane interface. Design/methodology/approach An analytical perturbation theory of the coupled system of particle and SAW is presented. It shows that in the weak-coupling regime, the SAW sensor detects the coupling stiffness rather than the additional mass of the particle at the interface. The frequency perturbation formula expressed in parameters of the geometry and mechanical properties of the contact is further derived. The frequency shift of a 262-MHz Rayleigh-type SAW in the oscillation configuration under the loading of multiple starch particles of different sizes has been measured. Findings The experiment results of a linear relationship between the frequency increase and the sum of the radius of particles to the power of 2/3 verified the validity of the theory of linking the SAW response to the geometry and mechanical properties of the contact. Originality/value The SAW sensor could serve as a new candidate for studying the details of mechanical properties of the micro-contact of the interface.