Materials tactile logic via innervated soft thermochromic elastomers

Yang Jin,Yiliang Lin,Mingqiao Ge,Michael D Dickey,Abolfazl Kiani,Ishan D Joshipura

doi:10.1038/s41467-019-12161-1

Yang Jin, Yiliang Lin + Show 4 more

Open Access

https://doi.org/10.1038/s41467-019-12161-1

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Abstract

Conventional machines rely on rigid, centralized electronic components to make decisions, which limits complexity and scaling. Here, we show that decision making can be realized on the material-level without relying on semiconductor-based logic. Inspired by the distributed decision making that exists in the arms of an octopus, we present a completely soft, stretchable silicone composite doped with thermochromic pigments and innervated with liquid metal. The ability to deform the liquid metal couples geometric changes to Joule heating, thus enabling tunable thermo-mechanochromic sensing of touch and strain. In more complex circuits, deformation of the metal can redistribute electrical energy to distal portions of the network in a way that converts analog tactile ‘inputs’ into digital colorimetric ‘outputs’. Using the material itself as the active player in the decision making process offers possibilities for creating entirely soft devices that respond locally to environmental interactions or act as embedded sensors for feedback loops.

Highlights

Sample0.2 A White background0.5 A Purple background Apply current OffTo understand the power required to achieve these changes in color, we reasoned that Joule heating generates power (P) based on the applied current (I) and the resistance of liquid metal (R) according to P = I2R
This paper demonstrates that silicones innervated with liquid metal circuits—which are completely soft and stretchable—are capable of a variety of interesting functions based on the ability to direct electrical energy through these dynamic circuits
Humans rely on color change in high-tech electronics as a primary means of human–computer interfaces[17,18]

Summary

Introduction

For a given current, decreasing the width of the liquid metal increased the temperature change due to increased Joule heating Increasing the current density—either through increased current or reduced width of the liquid metal—caused the color-changing regions to widen. The width of these regions agrees with thermal modeling done using COMSOL finite element simulations 6 and 7; more information about modeling see Supplementary Note 1) Taken in sum, these results underscore the relation between geometry and Joule heating for a given current

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