Hyperelastically stretchable strain gauges based on liquid metals and platinum-catalyzed silicone elastomers

This paper reports hyperelastically stretchable strain gauges based on a liquid metal (eutectic gallium-indium; EGaIn) and a platinum-catalyzed silicone elastomer (EcoFlex™). A custom liquid metal printing setup was operated in a pressure controlled mode to offer improved printing quality over the previously used flow-rate controlled mode [1]. Printed liquid metal strain gauges were tested under cyclic uniaxial stretching and twisting. By engineering the orientation of solid wires placed over two terminals of the printed liquid metal resistor, we achieved the stretchability of ~800 % which is the highest value reported so far, to the best of our knowledge.