Highly Stretchable Electromechanical Sensors with Ionotronic Knots Based on Hydrogel Fibers

Abstract Stretchable devices have gained increasing interest in recent years, particularly in the field of wearable electronics. Among them, fiber‐type devices with high mechanical conformability hold great potential to enable next‐generation wearable and interactive applications with their special structure and high compatibility with the well‐established textile industries. In this study, a hydrogel fiber providing large moisture retention and high mechanical compliance is fabricated, with which a new approach to enable highly stretchable electromechanical sensors based on knot structures is developed. Comparative analysis with common orthogonal textile structures reveal the superior performance of sensors based on ionotronic knots. Stress sensors with the double overhand knot exhibit ≈four times greater variation in capacitance than those with orthogonal structures, and sensors with the clove hitch knot exhibit a fast response time of 57 ms. Based on the characteristics of different knots, a sensor matrix based on clove hitch knots to map the pressure distribution, and a wearable mole code generator based on reef knots to recognize and encode wrist motions are developed. These applications demonstrate the excellent performance of knot‐architecture sensors and their great potential in the fields of smart fabrics and human–machine interactions.