Dynamic Shaping of Multi-Touch Stimuli by Programmable Acoustic Metamaterial

TL;DR

This paper presents a new active acoustic metamaterial with dual-state cells that can be electronically reconfigured in real-time to shape vibration patterns, enabling advanced tactile displays and information encoding.

Contribution

Introduction of a self-tuning, dual-state active metamaterial capable of real-time waveguide reconfiguration and tactile pattern shaping using simple, off-the-shelf components.

Findings

Deep subwavelength band gaps can be automatically matched to carrier signals.

Real-time reconfiguration of vibration patterns is achieved through electronic switching.

The metamaterial can be constructed with common smartphone vibration motors.

Abstract

Acoustic metamaterials are artificial structures, often lattice of resonators, with unusual properties. They can be engineered to stop wave propagation in specific frequency bands. Once manufactured, their dispersive qualities remain invariant in time and space, limiting their practical use. Actively tuned arrangements have received growing interest to address this issue. Here, we introduce a new class of active metamaterial made from dual-state unit cells, either vibration sources when powered or passive resonators when left disconnected. They possess self-tuning capabilities, enabling deep subwavelength band gaps to automatically match the carrier signal of powered cells, typically around 200Hz. Swift electronic commutations between both states establish the basis for real-time reconfiguration of waveguides and shaping of vibration patterns. A series of experiments highlight how these tailored acceleration fields can spatially encode information relevant to human touch. This novel metamaterial can readily be made using off-the-shelf smartphone vibration motors, paving the way for a widespread adoption of multi-touch tactile displays.