Harnessing re-programmable phase transitions to control the propagation of sound waves

TL;DR

This paper demonstrates the design and experimental realization of re-programmable metamaterials with reversible phase transitions using tunable magnetic lattices, enabling dynamic control of sound wave propagation and low-frequency wave filtering.

Contribution

It introduces a novel approach to create re-programmable metamaterials with reversible phase transitions using magnetic boundaries, overcoming previous manufacturing and non-linearity challenges.

Findings

Reversible phase transitions achieved in magnetic lattice-based metamaterials.

Real-time, ultra-low frequency tunable sound wave filter demonstrated.

Experimental validation confirms controllable sound propagation.

Abstract

Metamaterials can enable peculiar static and dynamic behavior (such as negative effective mass density, dynamical stiffness, and Poisson's ratio) due to their geometry rather than their chemical composition. The geometry of these metamaterials can be thought of as the phase of the material, which is usually fixed once the material is fabricated. While there exist many theoretical and numerical studies of metamaterials that can change phase, or re-program, experimental realizations remain limited due to challenges in manufacturability, the destructive nature of the re-programming and inherent non-linearities. Through a combination of analytical, numerical and experimental analyses, we utilize tunable, self-assembled, nonlinear magnetic lattices to realize metamaterials with reversible phase transitions. Our metamaterials are composed of free-floating disks, with embedded permanent magnets, confined within magnetic boundaries. We exploit the non-destructive nature of the adjustable magnetic boundaries to create a set of re-programmable metamaterials to control the propagation of sound waves. Furthermore, we demonstrate a robust, real-time tunable wave filter at ultra-low frequencies. Our findings can expand the metamaterials horizon into functional and tunable devices.