Design and Evaluation of Auxetic E-textile Stretch Sensors for Wearable Technology Applications

Electronic textiles (e-textiles) provide a great platform for creating stretch sensors in wearable applications as they are inherently flexible and stretchable allowing them to conform to the shape and movements of the human body. This study explores the integration of laser cut and 3D printed auxetic patterns into textile-based stretch sensors, investigating their design, fabrication, and sensing capabilities to develop a novel approach for creating flexible and highly sensitive e-textile stretch sensors for wearable applications. We employed two different biostable auxetic patterns to realize the stretch sensor structures and tested impedance change of the samples under repeated movements of stretching and relaxing. 3D printing of conductive filaments directly on fabric in an auxetic pattern resulted in reliable and repeatable stretch sensing capability. The study demonstrated that the stable and repeatable performance of e-textile stretch sensors depends on a combination of factors such as the fabrication method, conductive material, optimized auxetic geometry, base fabric recovery characteristics and the application of pre-stretching during fabrication.