A triboelectric-piezoresistive hybrid sensor for precisely distinguishing transient processes in mechanical stimuli

As a pivotal component in human-machine interface and autonomous robot, tactile sensors are imperative to own extra capability of perceiving transient mechanical stimuli, rather than remaining in the static sensing regime. In this work, a hybrid tactile sensor is proposed, which integrates a porous polydimethylsiloxane (PDMS) based triboelectric active sensing unit and a conductive carbon black (CB)/thermoplastic polyurethane (TPU) composite based piezoresistive sensing unit. This hybrid sensor responds well to both static and transient mechanical excitations, such that the entire process of “approach-contact-press-release-separation” in a tactile stimulus can be precisely distinguished. In addition, this sensor can detect the approaching and separating speed up to 100 mm s−1, with a good linearity between the contact or separation speed and the triboelectric voltage output. The two signals from the hybrid sensor can be combined to generate comprehensive and insightful information about a mechanical stimulus and differentiate nuances among similar stimuli. We demonstrate the application of the hybrid sensor in a smart boxing-training glove, which is capable of identifying different boxing punches and revealing detailed information about the impact of each punch.