Fully Textile Insole Seam-Line for Multimodal Sensor Mapping

Abstract

Here we demonstrate a fully-textile insole sensor capable of providing simultaneous pressure and wetness sensing. By utilizing a three-layer textile structure consisting of knit/non-woven materials and conductive yarns, we produced a pressure sensitive sensing array. An additional layer of embedded conductive yarns enabled mapping of wetness in the insole environment. The pressure sensing array was capable of detecting pressures up to 600 kPa, with enhanced sensitivity in the lower pressure regime (0-150 kPa) and was found to be stable to static/dynamic loading conditions following calibration. The system was demonstrated as an insole sensor for mapping plantar pressures during normal gait walking. As a wetness sensor, the system was capable of characterizing location and extent of wetness as well as distinguishing between ionic/non-ionic wetting fluids. We demonstrated detection of as little as $50~\mu \text{L}$ of saline solution at a single wetness sensing point. This fully-textile design provides conformal, breathable sensing for mapping pressures and wetness across curvilinear surfaces. This design enables spatial/temporal resolution of these parameters and could provide a method for long-term monitoring of dynamic skin interface environments to provide improved customized orthotic/orthopedic solutions.