A flexible tube-based triboelectric–electromagnetic sensor for knee rehabilitation assessment

•A new type of self-powered sensor with applications in angular motion sensing is presented.•Triboelectric and electromagnetic generators are hybridized in a singular package.•An optimized configuration is determined for the electromagnetic configuration of the self-powered sensor.•The potential of the device for joint and knee rehabilitation is discussed.•Design and modelling of both EMG and TENG parts are fully discussed.