Experimental Realization of a Reconfigurable Electroacoustic Topological Insulator

TL;DR

This paper demonstrates a reconfigurable electroacoustic topological insulator that uses programmable switches and piezoelectric patches to control wave propagation, overcoming scattering issues in elastic wave guiding.

Contribution

It introduces the first reconfigurable electroacoustic topological insulator with dynamic control of waveguides using programmable switches and external circuits.

Findings

Experimental validation of topologically protected interface waves.

Reconfigurable control of wave trajectories over broad frequency range.

Breaks inversion symmetry to create nontrivial bandgaps.

Abstract

A substantial challenge in guiding elastic waves is the presence of reflection and scattering at sharp edges, defects, and disorders. Recently, mechanical topological insulators have sought to overcome this challenge by supporting back-scattering resistant wave transmission. In this Letter, we propose and experimentally demonstrate the first \emph{reconfigurable electroacoustic} topological insulator exhibiting an analog to the quantum valley Hall effect (QVHE). Using programmable switches, this phononic structure allows for rapid reconfiguration of domain walls and thus the ability to control back-scattering resistant wave propagation along dynamic interfaces for phonons lying in static and finite-frequency regimes. Accordingly, a graphene-like Polyactic Acid (PLA) layer serves as the host medium, equipped with periodically arranged and bonded piezoelectric patches, resulting in two Dirac cones at the $K-$points. The PZT patches are then connected to negative capacitance external circuits to break inversion symmetry and create nontrivial topologically-protected bandgaps. As such, topologically protected interface waves are demonstrated numerically and validated experimentally for different predefined trajectories over a broad frequency range.