Switchless Oscillating Charge Pump-Based Triboelectric Nanogenerator and an Additional Electromagnetic Generator for Harvesting Vertical Vibration Energy.

According to energy crisis and increasing number of small electronics, energy harvesting is one of the most promising technologies for scavenging several types of wasted energy. Especially, with regard to vibrational energy harvesting, triboelectric nanogenerators and electromagnetic generators stand out due to their working mechanisms. Here, an oscillating charge pump-based hybrid generator with two triboelectric nanogenerators and an electromagnetic generator using a switching-free characteristic was fabricated with material optimization. To enhance the electrical output of the triboelectric nanogenerator, a concept of charge pumping with simply connecting an additional charge pump device and the nanostructure formation process on the contact metal layer were adopted. The electrical outputs were characterized as an output current of 9.17 μA with a current density of 83.2 mA m in the triboelectric nanogenerator. The power density of the triboelectric nanogenerator reached 4.45 W m with a 40 MΩ resistor. The electromagnetic generator showed an output current density of 0.91 A m. Moreover, with the cuboid structure, the device can sense the collision force with different angular displacements from 5 to 30°. The proposed hybrid generator with a simple structure can be applied to sensing applications with the one-point-fixed state.