A Motion Adaptive Self-Powered Wearable Sensor for Biomechanical Energy Transduction and Human Gait Sensing

Self-powered sensors have nowadays show a growing competitiveness and flexibility compared with traditional sensors that need additional power supply. For the design of self-powered wearable electronics sensing human gaits, it’s reasonable to gain energy directly from human activities, but how to effectively transduce biomechanical energy from variable low-frequency human motions and reflect information on human activities still remains an open issue. Here, we propose a motion adaptive self-powered wearable sensor for biomechanical energy transduction and human gait sensing mainly based on a well-designed magnetic rotor and wound coils. According to the kinetic analysis, the adopted rotational stroke of the rotor facilitates the multi-directional vibration adaptation. Both the instantaneous and statistic values of the output voltage are measured in experiments. A low optimal working frequency around the resonant frequency of 2.87 Hz is achieved to match the low frequency in human motions. And a broadband output performance under stronger excitations enables the sensor to operate effectively facing the irregularity of human activities. The treadmill test reveals that the sensor is capable of discriminating human gaits during different activities with varying intensities.