Triboelectric nanogenerators (TENGs) have emerged as a promising power solution for autonomous sensors, as they can be constructed using low-cost, lightweight, and environmentally friendly materials. However, the design of the ensuing power management circuit (PMC), intended to maximize energy extraction from the TENG, remains a challenge for circuit designers at both board and integrated circuit (IC) levels, especially due to the unique properties of the TENG output signal. Among the different circuit topologies proposed in the literature, this article focuses on the full-wave rectifier (FWR) with a dual output (DO). It is proposed to incorporate a switch at the input of the FWR-DO to increase the energy extracted from the TENG. The switch is instantaneously closed in synchronization with the maximum and minimum separation between electrodes, thereby generating a short circuit across the TENG. As a result of this short-circuit, the voltage at the two outputs of the FWR-DO can be adjusted independently to optimize energy extraction in both half cycles, which is not possible in conventional FWR-DOs. The proposed circuit, including the synchronized input switch, is evaluated theoretically, by simulations, and experimentally using an in-house fabricated TENG with a contact-separation topology. Additionally, its performance is compared with that obtained using conventional FWR and FWR-DO topologies. According to the results reported herein, the incorporation of the synchronized input switch generates an improvement in the energy extraction that depends on the symmetry of the voltage-charge plot related to the TENG. For the TENG under test, the energy improvement factor (with respect to FWR-DO) is 18% when the switch is incorporated.

Triboelectric nanogenerators (TENGs) have emerged as a promising solution for powering Internet of Things (IoT) sensor nodes and wearable electronics, owing to their use of low-cost, lightweight, and environmentally friendly materials. However, the distinctive characteristics of their electrical output, such as high voltage and time-varying internal capacitance, pose significant challenges for the design of efficient power management circuits (PMCs). The high output voltage of TENGs, which often exceeds the safe operating limits of integrated-circuit (IC) technologies, renders conventional IC-based PMCs unsuitable for optimal energy extraction. As a result, board-level PMCs, free from these voltage constraints, are essential for effectively managing the output power of TENGs. This article presents a comprehensive classification and critical review of recent board-level PMC designs tailored for TENG applications. Using a generic block diagram as a framework, various implementation strategies for each functional block are analyzed, highlighting their respective benefits and limitations. Particular focus is given to switching-stage configurations around the rectifier, which enable advanced techniques, such as synchronous electric charge extraction and synchronous switched harvesting on inductor. A comparative analysis of representative PMCs is conducted based on key mechanical and electrical performance metrics. Finally, unresolved challenges and promising research directions are discussed, providing insights into future development of high-efficiency TENG-based energy harvesting systems.