A comparative feasibility analysis for sensing swelling with textile-based soft strain sensors

Sensing edema or swelling in the body is a parameter of interest for many clinical and cosmetic applications of wearable technology. Edema creates heightened sensitivity to pressure points, making soft textile-based sensors particularly attractive. However, swelling induces slow, gradual changes in body circumferences, which can be difficult to sense accurately, especially with soft e-textile sensors. Anthropometric variability, sensor placement, and body movements further confound accuracy. Here, we explore the feasibility of accurately sensing ankle swelling through a comparative assessment of a set of sensors representing 3 soft sensing mechanisms in a linear-strain bench test under three frequency conditions. These sensors are then applied in a simulated swelling experiment to assess their performance relative to circumferential changes similar to those experienced in swelling. We find that two sensors (stitched and capacitive) demonstrate reliable performance that approximates or exceeds expert human measurement for swelling. Resistive polymer cord and capacitive sensors exhibited accurate response under medium- and high-frequency extensions.