Overlock-stitched stretch sensors: Characterization and effect of fabric property

The comfort of wearable sensors is often limited by the materials and construction methods of sensors. Here, we present a textile-based stretch sensor that is formed using a common industrial sewing machine, in an overlock formation. Swapping a single thread in the stitch for a conductive thread renders the stitch responsive to stretch through opening and closing short circuits in the looped structure of the exposed conductor. However, the sensor response is influenced by the mechanical properties of the textile to which it is stitched. We explore the influence of fiber content (with an emphasis on elastomeric fiber content) on the baseline drift, response range, and hysteresis of the stitched sensor. Results show that the sensor provides a reliable and repeatable response, with a linear region that spans from the relaxed position to between 18 and 29% elongation. Average drift of about 0.5 Ohm and hysteresis of about 1 Ohm were measured. Effects of fiber content were observed, but do not show clear relationships to percentage of elastomer content.