Micromolding-in-Capillary based Fabrication of Liquid Metal Patterned Structures for Soft Robotics

Liquid metals offer high intrinsic stretchability and electrical conductivity at room temperature which make them potential material candidates to develop stretchable high-performance electronics. The present paper reports a facile fabrication method to pattern liquid metals. A micromolding-in-capillary process is developed wherein liquid metals are casted into desired shapes on stretchable substrates such as Ecoflex^TM. First, 3D printing is employed to realize a master template of a desired shape and then the grooved stretchable substrates are formed to fill-out with the liquid metals. The efficacy of the developed technique is demonstrated by fabricating stable stretchable interconnects, and mechanical sensors. The obtained experimental data shows that liquid metal interconnects maintain high electrical conductivity under stringent linear strain up to 160 %with the maximum relative change in resistance of 2%, and under wide temperature range (–5 to 50°C) reaching maximum of –2.5% relative change at –5°C. As a mechanical sensor, the results show a linear increase in resistance change with a stepwise increase in the applied force from 3–7N.