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Overspeed information monitoring and collecting becomes increasingly important with the rapid development of intelligent transportation, but current overspeed monitoring technologies are constrained by traditional power-supply for large-scale use. Herein, we proposed a self-powered overspeed wake-up alarm system (SOWAS) based on triboelectric nanogenerators. The SOWAS consists of an energy harvesting triboelectric nanogenerator (E-TENG), an energy management module (EMM), an overspeed sensing triboelectric nanogenerator (S-TENG), a power-switch module (PSM) and a wireless transceiver module (WTM). The E-TENG and EMM are used for mechanical energy harvesting, management, and powering for the SOWAS, while the S-TENG, PSM and WTM are employed for active overspeed monitoring and alarm signals transmitting. When the vehicle speed exceeds the setting threshold, the PSM will be activated, and the WTM will send alarm signals with the harvested energy. The response characteristics dependence of the SOWAS on various working parameters were investigated in detail. The developed SOWAS could work sustainably in unattended traffic environment without external power supply for autonomous overspeed monitoring and alarming. Meanwhile, intelligent monitoring of overspeed and improved energy utilization were achieved. This work has enormous potentials and promising prospects for TENG in intelligent transportation, Internet of Vehicles and autonomous driving. [Display omitted] • A self-powered overspeed wake-up alarm system (SOWAS) based on TENGs is developed. • The SOWAS enables sustainable self-powered overspeed monitoring and alarm by harvesting the mechanical energy from traffic system. • Intelligent overspeed monitoring is achieved by the designed wake-up circuit and the efficient use of energy. [ABSTRACT FROM AUTHOR]

Obtaining a wear-resistant, high-output, flexible direct current (DC) friction energy harvester is quite important for implementing self-powered portable electronic devices and Internet of Things (IoT). In this work, a direct current flexible textile organic tribovoltaic nanogenerator (FT-OTG) is reported, which is consisted of blended film of 11.11% poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT: PSS) and 88.89% polyvinyl alcohol (PVA), a hydrophilic conductive ink, a hydrophobic conductive textile and Al slider. The working mechanism of OTG is that after absorbing friction energy, abound electron-hole pairs are excited at the metal-semiconductor interface. These carriers move directionally under the joint drive of electrostatic field and the built-in electric field to form a current. After PVA doping, the output performance of DC-OTG, including open-circuit voltage and short-circuit current, is improved 5.6 times and 4.2 times, respectively. Furthermore, the mechanical properties of blended film, such as wear resistance, elongation and tensile strength, are improved, among which elongation at break is increased by 8 times and tensile strength increased by 3.2 times. By simplify series connecting, 3 FT-OTGs can constantly power portable electronics, like electronic watch, thermometer and calculator, respectively. This work provides an effective way for simultaneously enhanced output performance and mechanical properties of FT-OTG, which is expected to be a robust way for harvesting friction energy for self-powered electronics device and IoT sensors. [Display omitted] • A direct current FT-OTG is reported. By simplify series connecting, 3 FT-OTGs can constantly power portable electronics. • The enhancement mechanism is the E CE and E built-in field jointly promote the directional motion of charge carriers. • After PVA doping, output performance and mechanical performance have been significantly improved. [ABSTRACT FROM AUTHOR]

Power management is an efficacious route to promote the development of triboelectric nanogenerators (TENGs), in which the buck switch for efficient energy extraction has always been a challenge. Here, we propose a three-port cantilever buck switch which can autonomously release energy from the TENG in maximum by the generated electrostatic field of the TENG. The influence of closing voltage of the buck switch on different structure parameters has been thoroughly investigated. The U-Q curve indicates that the optimal energy extraction can reach 90.86%, and the matched impedance of the TENG is reduced from 60 MΩ to 470 kΩ. Compared to the output power at matched impedance, the average power managed by this three-port cantilever buck switch is increased by 1.554 times, which can power the Bluetooth device, electronic watch, calculator and thermo-meter. This work has realized ultra-efficient power management of TENG by leveraging an autonomous cantilever buck switch, which can contribute to the efficient utilization of micromechanical energy. • A three-port cantilever buck switch controlled by the electrostatic field of the TENG for its power management is pioneered. • A detailed analysis of the force-electricity conversion process has been conducted. • U-Q curve and P-R curve has been linked to characterize the output efficiency for the first time. [ABSTRACT FROM AUTHOR]