Search

Recently, there is a growing emphasis on the utilization of wearable devices for monitoring various aspects of human body movement. However, a persistent obstacle in the way of their widespread adoption is the requirement for an external power to keep them operational. Triboelectric nanogenerator (TENG), an emerging power technology, can convert low-frequency mechanical energy into real-time electrical signals and obtain corresponding mechanical motion characteristics, enabling self-powered human body signal monitoring with advantages of compact size, easy preparation, and low cost. It offers a promising avenue for advancing the field of human motion monitoring without an external power. In this review, we systematically review the latest progress of TENG-based human body signals sensors (HBSSs) in terms of working mechanism, design principles, function integrations and monitoring accuracy, as well as the corresponding TENG based wearable device advantages in sensitivity, stability and wearing comfort. According to the monitoring field, TENG-based HBSSs can be divided into two kinds of researching directions, which contain the basic physiological signals monitoring and motion signals monitoring. Some representative applications in these two aspects are summarized to highlight the superiorities of TENG-based HBSSs. Further, the current challenges and promising solutions for future TENG-based HBSS are outlined, including sensitivity, stability, and wearing comfort, which will better steer new researchers toward a deeper understanding and exploration of TENG for the self-powered sensing technology.

Triboelectric nanogenerator (TENG) based on Maxwell’s displacement current as the driving force has broad applications in energy harvesting and self-powered sensors. However, the effect of doped ferromagnetic materials with bearing an external magnetic field on TENG’s displacement current has not been clearly revealed. Herein, a ferromagnetic-assisted Maxwell’s displacement current is proposed for improving TENG output based on polymer/iron composite film (PICF). Based on Maxwell’s equations, the magnetizing current of the ferromagnetic medium coupled with the displacement current is investigated theoretically for boosting TENG output and verified simulationally and experimentally. Comparing TENG output with the magnetization method of PICF, the initial magnetization significantly determines the coupling mechanism between magnetizing current and displacement current. Moreover, the strength and direction of an external magnetic field further reveal the mechanism impacting the initial magnetization on TENG’s displacement current. A short-circuit current density of 27mA/m2and instantaneous power density of 2W/m2are achieved by the champion TENG, which are 800% and 8200% higher than those of pristine polymer. Finally, a distributed TENG array is developed for efficiently harvesting distributed energy to demonstrate the application potential of the improved TENG in self-powered systems. This work elaborates the coupling mechanism of the magnetizing current with TENG’s displacement current, which provides general guidance for investigating efficient energy harvester toward self-powered sensors, wearable electronics and flexible electromagnetic shielding devices.