Wearable Flexible Touch Interface Using Smart Threads

We present an innovative concept for a touch interface made from strain sensing smart threads. The Flexible Touch Interface (FlexTI) is based on assembling strain sensing threads in a 2D matrix assembled directly on skin or as a wearable device. A touch or pressure stimuli anywhere on this matrix results in a deformation (strain) of threads. Measurement of resistance change due to strain in these threads creates an accurate 2D map of touch that can be used for human machine interface. The innovative smart threads are made through dip coating of Carbon Resistive Ink and EcoFlex on cotton threads. We present preliminary results on FlexTI made from a 4x4 array of smart strain sensing threads assembled on a square PMMA scaffold. Thread-to-thread variability was addressed using a nearest neighbor averaging approach. A simple machine learning classifier was used to accurately map the strain information to one of the 16 intersection points. Experimental results validate the performance of FlexTI.