Highly Stretchable Textile Knitted Interdigital Sensor for Wearable Technology Applications

Wearable technology applications have experienced remarkable development and advancements, with soft and stretchable strain sensors playing a significant role in this progress. Despite the promising potential of combed-shaped interdigital capacitive strain sensors in wearable electronics, several challenges exist, including limited stretchability, universal mass fabrication, and seamless integration into diverse clothing parts. This study presents a textile knitted interdigital capacitive sensor that incorporates stretchable conductive yarn, produced using textile twisting technology, to achieve stretchability and adaptability, allowing seamless conformation to human body movements and textile materials. The fabrication process involves embedding the interdigital electrodes and interconnections directly into the fabric through textile knitting technology, ensuring robust integration. Furthermore, this work presents opportunities for commercializing the stretchable interdigital strain sensor through a low-cost and mass production strategy. Electromechanical characterization demonstrates exceptional performance with high stretchability (≈230%), excellent linearity (R² = 0.997), a gauge factor (GF) of −0.68 representing relative capacitance change, and a rapid response time of 66 ms. To validate the usability of sensors in wearable technology, a knee brace application is employed to investigate capacitance changes during walking and cycling exercises. This approach will accelerate the accessibility of wearable stretchable interdigital sensors for all.