A low-cost and highly integrated sensing insole for plantar pressure measurement

Plantar pressure measurement plays an important role in monitoring health and sports performance. Here, instead of embedding force sensitive resistors in the insole, we developed a simple and low-cost, highly integrated, textile-only sensing insole for the measurement of plantar pressures. These sensors were composed entirely of fabric, and utilized a capacitive mechanism, with silver cloth as electrodes and cotton cloth as the dielectric element. The similarity of elasticity and flexibility between sensor and insole enabled them to be closely integrated, and avoided negative impact on comfort. Additionally, the silver cloth electrodes contributed good antibacterial properties. The sensors exhibited fast response, negligible hysteresis, high sensitivity (0.947 MPa−1), and good stability. Based upon capacitive responses to plantar pressures from the instrumented insole, gait phases (events) in different patterns were detected, giving the potential to monitor the health of the foot.