Knitted Inductive Flex Sensors for Wearable Applications

We introduce a knitted inductive flex sensor which seamlessly integrates a coil and a capacitor into a soft and flexible tubular knit. By knitting enameled copper wires, we form a self-supporting coil, whose inductance changes with stretching and bending. Knitting both a coil and a parallel-wire capacitor, we create a textile resonant LC circuit, while preserving the softness, elasticity, and breathability of knitted textiles. In this paper, we present the fabrication process using an industrial knitting machine, evaluate sensor sensitivity and hysteresis over 100 bending cycles, and demonstrate the sensors versatility across joints of different radii. Our results show that knitted inductive sensors combine the wearability of soft textiles with the stability of inductive sensing, opening new sensing opportunities in healthcare, rehabilitation, and interactive electronic garments.