Multi-Element Strain Gauge Modules for Soft Sensory Skins

In this paper, we describe the fabrication and testing of a sensory module composed of resistive strain gauges in an elastomer substrate. Each module contains three resistive gauges, providing sufficient information to reconstruct the geometry of the module. The modules are fabricated from two bonded sheets of silicone elastomer. The sensing element is a resistive strain gauge based on room-temperature liquid gallium-indium alloy contained within microchannels in the substrate. We demonstrate the functionality of the module by mechanically stretching it over a template and measuring the change in resistance of the embedded liquid metal strain gauges. Starting with known strains, we calibrate the device and fit a quadratic model. With the model and the measured error distribution, we can predict the uncertainty in the reconstructed position of the corners of the triangular modules, which we refer to as nodes.