[en] Highlights: • Rotational Pulsed-TENGs have rarely been developed because of the difficulty in designing rational STMSs. • Rotating freestanding Pulsed-TENGs (RF-Pulsed-TENGs) are realized through integrating STMSs on electrode layer. • Both alternating current and unidirectional current RF-Pulsed-TENGs are realized. • The on–off states of the STMSs can match well with the rotation frequency of the RF-Pulsed-TENGs. • A self-powered system consisting of gearbox, efficient passive PMC, and an RF-Pulsed-TENG has been demonstrated. With the merits of zero internal equivalent resistance and maximized output energy, the pulsed mode triboelectric nanogenerators (TENGs) can achieve impedance matching with the power management circuits (PMCs), showing wide application prospects in self-powered systems. The key for developing Pulsed-TENGs lies in designing synchronously triggered mechanical switches (STMSs). However, rotational TENGs, as a promising configuration for harvesting mechanical energy, have rarely been designed as pulsed mode because of the difficulty in fabricating rational STMSs. Herein, rotating freestanding triboelectric-layer Pulsed-TENGs (RF-Pulsed-TENGs) are realized through integrating STMSs on triboelectric layers in one step by printed circuit board process. Since the on-off states of the STMSs can match well with the rotation frequency, the output voltage and energy of the RF-Pulsed-TENGs are maximized regardless of the rotation frequency or load resistance. Both alternating current and unidirectional current output RF-Pulsed-TENGs have been realized, and the energy storage efficiency of their corresponding passive PMCs can reach 51.6% and 52.0%, respectively. The system consisting of a gearbox, a passive PMC, and a RF-Pulsed-TENG has been demonstrated to power a range of electronic devices, such as calculators, electronic watches, and temperature/humidity meters, offering significant advantages and promising applications in efficient mechanical energy harvesting and self-powered sensing.

[en] Highlights: • Charge transfer between TENG and the inner capacitor of voltmeters makes the measured voltage lower than its actual value. • A general charge compensation strategy is proposed for calibrating the measured voltage of a TENG. • The FCD method and VCF method are developed to calibrate the open-circuit voltage of TENGs. • The output voltage of a TENG is calibrated through the equivalent impedance including the inner capacitance of voltmeter. The voltage is a key parameter of a triboelectric nanogenerator (TENG). However, when the voltage is measured by the voltmeters with a capacitive measurement circuit, there is a charge transfer between the TENG and the inner capacitor, making the measured voltage lower than its actual value. In this paper, a general charge compensation strategy is proposed for calibrating the measured voltage of a TENG based on the analysis of the capacitive measurement circuit. Two methods, the fixed capacitance derivation (FCD) and the variable capacitance fitting (VCF), are developed to calibrate the open-circuit voltage (V_oc) of TENGs, and the calibration formulas of V_oc are given, respectively. Firstly, a sliding freestanding triboelectric-layer mode TENG is taken as an example and the two methods are used to calibrate actual V_oc. The results are consistent with that measured by the ammeter with non-capacitive measurement circuit, verifying the validity of the charge compensation strategy. For the other three basic working modes TENGs, the measured V_oc are calibrated by the FCD method, which illustrate the universality of the charge compensation strategy. Finally, the relationship between the output voltage of a TENG and the load impedance is calibrated through the equivalent impedance including the inner capacitance of the voltmeter. The proposed charge compensation strategy for calibrating the voltage of a TENG measured by a capacitive circuit is of great theoretical and application significance for the establishment of a comprehensive evaluation system for TENG’s output performance.

[en] Highlights: • A self-powered photodetection system based on Pulsed-TENG is developed. • The output voltage of Pulsed-TENG and the photodetection results are not affected by the frequency of mechanical stimuli. • Based on the output characteristic of Pulsed-TENG, both current and voltage modes are developed. • Based on the voltage mode, a self-powered photodetection system with visual display function is developed. The self-powered sensing systems based on impedance matching effect have been proposed by using a triboelectric nanogenerator (TENG) as power source, which have attracted widespread attention in the field of Internet of Things. However, the output voltage and current of the conventional TENG are affected by not only the load impedance but also the working frequency of TENG, leading to inaccurate sensing results in actual working environments with random mechanical stimuli. For solving this problem, a self-powered sensing system using a Pulsed-TENG with a synchronous trigger switch has been proposed here, in which the output voltage and current of Pulsed-TENG are independent on its working frequency. The measured performances of a self-powered photodetector have verified that same detection results could be obtained for various rotation frequencies of a rotating Pulsed-TENG. Two self-powered detection modes, current mode and voltage mode, have been developed. In the current detection mode, the output current increased linearly with light intensity, and the detectable range of light intensity is 0–1 W/m². In the voltage detection mode, the output voltage is inversely proportional to the light intensity, and the detectable range of light intensity is 9–403 W/m². Finally, a self-powered photodetection system with visual display function has been developed, in which the light intensity can be displayed intuitively by the number of lighted LEDs. Since the output voltage and current of Pulsed-TENG are independent on its working frequency, the self-powered sensing system based on Pulsed-TENG proposed here has provided a promising strategy suitable for the actual working environments with random mechanical stimuli.