Unidirectional-current triboelectric nanogenerator based on periodical lateral-cantilevers

Abstract In view of sustainable energy sources to power the Internet of Things, recently an emerging mechanism of environmental energy harvesting has been developed and named triboelectric nanogenerator (TENG), which has been proven to be clean and robust. However, the intrinsic feature of alternating-current (AC) output of TENG greatly limits its further real-life applications, since an extra rectifier circuit must be employed to convert it to be unidirectional-current output, which increases the complexity and cost of self-powered microsystem integration. Herein, we proposed a new unidirectional-current triboelectric nanogenerator (UC-TENG) based on an innovative design of periodical lateral-cantilevers. With the help of the combination of specially-patterned conductive networks (i.e., inner and outer connections) and lateral-cantilevers placed on the comb bars of their comb-shaped structures, the motion of charges is controlled in a sole direction to form a unidirectional-current flow. The operation mechanism of the proposed UC-TENG was systematically investigated by FEA (finite-element analysis) simulation and electrical measurements, and the uniformly stably unidirectional feature of electric waveforms was proven. The maximum open-circuit voltage, short-circuit current and power density achieved 300 V, 1.4 μA and 15.68 mW/m2, respectively. Moreover, the fabricated UC-TENG was successfully demonstrated to power capacitors and low-power-consumption electronic devices (i.e., thermometer and calculator) directly and continuously. This novel UC-TENG based on lateral-cantilevers simplifies the power management circuit of traditional TENG by avoiding the rectifier circuit, which significantly broadens the attractive potentials of TENG by improving the integration of self-powered microsystems.