In situ microstructural and electrical characterizations of liquid metal stretchable conductors

A versatile stretching setup has been developed for in-situ microstructural testing of flexible conductors in combination with X-ray scattering studies at the synchrotron beamlines. The application of the in-situ stretching setup is demonstrated on a prototype of Ag flakes and liquid metals on stretchable elastomers. The new setup allows material structural changes to be monitored by X-ray scattering in direct combination with electrical response, allowing their direct correlation. The versatile setup could be operated with any type of flexible conductor with controlled stretching steps and rates, and up to a maximum stretching of 200 %. Microstructural changes are determined by grazing X-ray scattering technique during the whole stretching cycle: before, during and after the application of strain. The stretchable conductor (Ag flakes/EGaInPs) is shown to be stable up to a threshold strain of 15 %, followed by a phase transition and an increase in resistance at higher strains. Due to the compact and versatile design of the stretching setup, the experiment for direct microstructural and electrical correlation under applied strain could be easily adapted to different synchrotron beamlines. • Developed a compact in situ stretching setup enabling simultaneous structural and electrical measurements up to 200 % strain • Demonstrated stable microstructure and low electrical resistance in Ag-flake/EGaInPs elastomer composites up to a threshold strain of 15 % • Revealed strain-induced Ag 2 Ga intermetallic phase formation beyond 15 % strain, directly correlating with a sharp increase in resistance • Provided critical insights into real-time structure–property relationships under mechanical deformation for optimization of stretchable conductors