Self-Healing Flexible Conductive Film by Repairing Defects via Flowable Liquid Metal Droplets.

Ruiwen Niu,Guofu Zhou,Mingliang Jin,Hao Wu,Jinwei Gao,Zhibin Yan,Lingling Shui,Jieping Cao

doi:10.3390/mi10020113

Abstract

Self-healing flexible conductive films have been fabricated, evaluated, and applied. The film is composed of a fragile indium tin oxide (ITO) layer covered with sprayed liquid metal (LM) droplets. Self-healing of electrical conductivity is achieved via spontaneous capillary wicking of LM droplets into cracks/defects of the ITO film. The liquid metal adhering onto the ITO layer can also connect the ITO fragments during bending to keep the overall conductivity of the composite LM/ITO film stable. Stable and reversible electrowetting performance has been achieved with the composite LM/ITO as the conductive film, in either flat or curved states.

Highlights

Flexible and stretchable electronic devices have attracted enormous attention among emerging areas, including flexible displays [1], solar cells [2], radio-frequency identification (RFID) tags [3], flexible organic light-emitting diodes (OLED) [4], and portable and wearable electrical devices, including clothing or biomedical devices [5]
When subjected to tensile or fatigue loading, indium tin oxide (ITO)-poly(ethylene terephthalate) (PET) lamination would be susceptible to tensile micro-cracks, which in turn leads to the increase of sheet resistance of ITO film and the degradation of optical transmission [8,9,10]
FIlnexoibrdilietrytaoncdoSmelpf-ahreatlinvgeloyf ethveaFluilamtes the film flexibility, we examined and compared the fatigue perfoIrnmoarndceerotfoscinogmlep-aITraOti,vseilnygelev-aLlMua,taentdhecofimlmpoflseitxeibLiMlity/,ITwOe fielxmams oinnePdEaTndsucbosmtraptaerse,dretshpeefcatitvigeulye, Rabpases0enrddafdneoeimmdrnmgRooanncanyssrcctterrleeaatosttheeffeddrsosiinhimnngeeFl0Fetii-tggroIueTus2rOrie0ess,0t4as04in.naacFngneilgddeou-fFSLraie2Mg.fi4uF,alrmaiepgnulSdbor2etecs.fooStFmrh3ieeagpa–uroncersldesiathteSaiovf3LtwaeeM–rscch/ctIeahsTrnheOtgoasewihfnsielsomcetyfthscereloleeesnsscihtsPorteifEaecnbTtrecersenesudisvsbiitasnsatrtgnayr,nacineatcenge(s∆d,wvRra∆ei/rtsRhyRpi=0ebn,cegRwtni−wvdheiReinltry0heg), versus bending cycles for single-ITO, single-liquid metal (LM), and composite LM/ITO films. ∆R/R0 was over 1300 for ITO and below 1.0 for single-LM and LM/ITO during the 2000 cycles of fatigue tests

Summary

Introduction

Flexible and stretchable electronic devices have attracted enormous attention among emerging areas, including flexible displays [1], solar cells [2], radio-frequency identification (RFID) tags [3], flexible organic light-emitting diodes (OLED) [4], and portable and wearable electrical devices, including clothing or biomedical devices [5] In these devices, flexible conductive film is one of the key components. One of the critical technical matters is the mechanical mismatch between common rigid conductive materials and soft supporting substrates, which leads to the formation of cracks or even delamination at interfaces of different materials upon an increased number of mechanical deformations. This has become one of the critical concerns for practical and long-term applications. An electrowetting on dielectric (EWOD) device, with a liquid-infused-membrane (LIM) as the flexible hydrophobic insulating layer, and a composite LM/ITO film, as the flexible conductive layer, have been fabricated and evaluated, showing excellent reversibility and low hysteresis of electrowetting performance

Materials and Methods

Electrowetting Performance on the Flexible Conductive Films

Conclusions