Conductive liquid metal elastomer thin films with multifunctional electro-mechanical properties

A B M Tahidul Haque,Angel Martinez,Michael D Bartlett,Qibing Pei,Junfeng Gao,M Ravi Shankar,Ravi Tutika,Mohsen Tabrizi,Meng Gao,Julie Mills,J Arul Clement

doi:10.1088/2399-7532/abbc66

Abstract

Wearable electronics, conformable sensors, and soft/micro-robotics require conductive yet stretchable thin films. However, traditional free standing metallic thin films are often brittle, inextensible, and must be processed in strict environments. This limits implementation into soft technologies where high electrical conductivity must be achieved while maintaining high compliance and conformability. Here we show a liquid metal elastomeric thin film (LET) composite with elastomer-like compliance (modulus < 500 kPa) and stretchability (>700%) with metallic conductivity (sheet resistance < 0.1 Ω/□). These 30–70 µm thin films are highly conformable, free standing, and display a unique Janus microstructure, where a fully conductive activated side is accompanied with an opposite insulated face. LETs display exceptional electro-mechanical characteristics, with a highly linear strain-resistance relationship beyond 700% deformation while maintaining a low resistance. We demonstrate the multifunctionality of LETs for soft technologies by leveraging the unique combination of high compliance and electrical conductivity with transfer capabilities for strain sensing on soft materials, as compliant electrodes in a dielectric elastomeric actuator, and as resistive heaters for a liquid crystal elastomer.

Highlights

We demonstrate the multifunctionality of liquid metal elastomeric thin film (LET) for soft technologies by leveraging the unique combination of high compliance and electrical conductivity with transfer capabilities for strain sensing on soft materials, as compliant electrodes in dielectric elastomeric actuator (DEA), and as resistive heaters for liquid crystal elastomer (LCE)
We demonstrate the multifunctionality of LETs for soft technologies by leveraging the unique combination of high compliance and electrical conductivity with transfer capabilities for strain sensing on soft materials, as compliant electrodes in dielectric elastomeric actuator ce pte (DEA), and as resistive heaters for liquid crystal elastomer (LCE)
Creation of liquid metal (LM) electroncis has been demonstrated by pressure induced sintering of LM droplets, [30,31,32] stretching enabled conductivity of pt polymerized LM networks, [33] and LM micro-channels inside elastomers. [34,35,36] Patterned traces can be developed by direct writing, [18] printing and stencil approaches, [37,38,39] and inkjet-printing [40] or laser writing [41,42] which are subsequently encapsulated by elastomers

Summary

Introduction

Introduction ptSoft electronics and machines simultaneously demand mechanical stretchability and us cri compliance with high electrical conductivity. [1,2,3,4,5] Key to these technologies are stretchable and conductive thin films which can deform into complex shapes to enable actuation, [6] sensing for electronic skins and smart clothing, [7,8,9,10] and energy storage. [11]traditional metallic conductors (Au, Ag, Cu), semiconductors (Si, Ge), and metal oxides (indium tin oxide (ITO)) thin films are not directly applicable in stretchable electronics due to their inherent stiffness and low elastic extensibility. [4,12] One approach to an overcome this limitation is to pattern curvy or buckled conductive traces on deformable substrates. [13,14,15] These materials can be bent and twisted, but their stretchability can be limited. [12] rigid yet conductive micro/nanoparticles of carbon nanotubes (CNTs), graphene, or metal nanoparticles can be incorporated in elastomers as composites to improve stretchability, but electrical conductivity is often compromised, especially under large deformations. [12] Notably, conductive particles spread by spray coating, [4] brush painting, [16] inkjet printing, [16] and drop casting [12] can be displaced during repetitive applications. We demonstrate the multifunctionality of LETs for soft technologies by leveraging the unique combination of high compliance and electrical conductivity with transfer capabilities for strain sensing on soft materials, as compliant electrodes in dielectric elastomeric actuator (DEA), and as resistive heaters for liquid crystal elastomer (LCE). We demonstrate the multifunctionality of LETs for soft technologies by leveraging the unique combination of high compliance and electrical conductivity with transfer capabilities for strain sensing on soft materials, as compliant electrodes in dielectric elastomeric actuator ce pte (DEA), and as resistive heaters for liquid crystal elastomer (LCE).

Results

Conclusion