Non-resonant and low-frequency triboelectric-electromagnetic hybridized nanogenerator for vibration energy

As the age of the internet of everything begins, the demand for various sensors to communicate with each other is soaring. As the lifeblood of the sensing system, reliable energy supply is the key consideration. Environmental mechanical energy harvesting has been a key technology for self-powering sensing system, which can convert mechanical energy into electric energy. Here, we present a non-resonant triboelectric-electromagnetic hybridized nanogenerator, which can scavenge low-frequency vibration energy from environmental vibration. In the device a rotating gyro is used as a core component. An embedded magnet and four coils arranged evenly around at the bottom of the shell form an electromagnetic generator (EMG), and a piece of triboelectric film pasted on the outer surface of the gyro together with a bottom electrode constitutes a triboelectric nanogenerator, (TENG). With the design of rotating gyro, a high sensitive energy capture can be realized under low frequency and irregular vibration. Under the rotation and revolution of the gyro, the triboelectric and electromagnetic energy will be generated. Through theoretical analysis and software simulation, the working principle of the device is expounded. Based on a linear motor platform, the influences of oscillation frequency and amplitude are systematically studied, and the maximum power of 0.084 mW under a loading resistance of 20 MΩ and 4.61 mW under 800 Ω are obtained at a driving frequency of 2 Hz by the TENG and EMG, respectively. The energy conversion efficiency of the system is 0.45%. Moreover, by placing the devices on the legs and arms of the human body respectively, the ability of the hybridized nanogenerator to capture the simple movement energy of the human body is further verified. After that, a self-powering pedometer module is successfully integrated with the energy storage unit. Under the excitation provided by running a body, the hybridized nanogenerator can provide a 20-s pedometer normal operation after charging a capacitance of 100 μF to 3.2 V. This research not only provides a new idea for the efficient acquisition of vibration energy, but also has potential applications in the energy supply of self-powered sensors.