Omnidirectional Bending and Pressure Sensor Based on Stretchable CNT-PU Sponge

TLDR

Bending and pressure sensors are essential for monitoring human motion, but most are separate devices. They construct a stretchable sensor from two orthogonal carbon‑nanotube–polyurethane sponge strips whose resistance varies with bending direction and pressure, enabling simultaneous determination of bending distance, direction, and pressure through a calibration function and triboelectric discrimination. The sensor achieves bending distance and angle errors below 4%.

Abstract

Bending and pressure sensors are very essential for evaluating external stimuli in human motions; however, most of them are separate devices. Here, two orthogonal carbon nanotube–polyurethane sponge strips (CPSSs) are used, each of which has different resistances when bent or pressed, to fabricate a multi-functional stretchable sensor capable of detecting omnidirectional bending and pressure independently. Due to the shape of the strip, the resistance of CPSS changes differently when bent along different directions. Based on this feature, two perpendicular CPSSs can reflect information of both bending distance and bending direction. After basic measurement data are obtained, a function set can be formulated to calculate bending distance and bending direction simultaneously. The errors of bending distance and bending angle can be controlled to less than 4%. With the help of the triboelectric effect, which only happens when the device is pressed, the sensor can differentiate bending and pressure effectively, ensuring the device works in complex situations.