Elastic wave manipulation implemented using a locally resonant metasurface with digitally tunable piezoelectric shunts

Abstract

A tunable metasurface consisting of an array of piezoelectric unit cells is demonstrated to anomalously refract incident elastic wavefronts along a target direction. Each surface bonded transducer (PZT) is shunted with an individually calibrated synthetic inductor to form a local resonator, which is then tuned to modify the local dispersive characteristics of each unit cell and implement discrete phase shifts. The analog synthetic inductances are integrated with digital potentiometers to realize online tunability, allowing the metasurface to be recalibrated to accommodate different incident wave frequencies or target angles of refraction without requiring any physical alteration of the host structure. A microcontroller unit (MCU) then reads the stored empirical data and designates the appropriate settings for each digital potentiometer in order to realize the targeted waveguiding behavior for a specified incident wave frequency.