Conventional and pulsed hybrid triboelectric nanogenerator with tunable output time and wider impedance matching range

Sliding grating-structured triboelectric nanogenerators (SG-TENGs) can multiply transferred charge, reduce open-circuit voltage, and increase short-circuit current, which have wide application prospects in self-powered systems. However, conventional SG-TENGs have an ultrahigh internal equivalent impedance, which reduces the output voltage and energy under low load resistances (<10 MΩ). The Pulsed SG-TENGs can reduce the equivalent impedance to near zero by introducing a synchronously triggered mechanical switch (STMS), but its limited output time causes the incomplete charge transfer under high load resistances (>1 GΩ). In this paper, a conventional and pulsed hybrid SG-TENG (CPH-SG-TENG) is developed through rational designing STMS with tunable width and output time. The matching relationship among grid electrode width, contactor width of STMS, sliding speed, and load resistance has been studied, which provides a feasible solution for simultaneous realization of high output energy under small load resistances and high output voltage under high load resistances. The impedance matching range is extended from zero to at least 10 GΩ. The output performance of CPH-SG-TENG under low and high load resistances are demonstrated by passive power management circuit and arc discharge, respectively. The general strategy using tunable STMS combines the advantages of conventional and pulsed TENGs, which has broad application prospects in the fields of TENGs and self-powered systems.

On the Possibility of Developing Magnetostrictive Fe-Co/Ni Clad Plate with Both Vibration Energy Harvesting and Mass Sensing Elements

The severe acute respiratory syndrome coronavirus (SARS-CoV-2) has spread rapidly around the world. In order to prevent the spread of infection, city blockades and immigration restrictions have been introduced in each country, but these measures have a severe serious impact on the economy. This paper examines the possibility of both harvesting vibration energy and detecting mass by using a magnetostrictive alloy. Few efforts have been made to develop new magnetostrictive biosensor materials. Therefore, we propose magnetostrictive Fe-Co/Ni clad steel vibration energy harvesters with mass detection, and we numerically and experimentally discuss the effect of the proof mass weight on the frequency shift and output voltage induced by bending vibration. The results reveal that the frequency and output voltage decrease significantly as the mass increases, indicating that the energy harvesting device is capable of mass detection. In the future, device miniaturization and the possibility of virus detection will be considered.

New Type of Thermoelectric CdSSe Nanowire Chip

Facing the increasingly serious problem of environmental pollution and energy waste, the thermoelectric generator has been attracting more and more attention owing to its advantages including low cost, no pollution, and good stability. The family of thermoelectric material is constantly extended with enhanced performance. Note that nanostructuring can enhance thermoelectric performance. However, the most recent excellent material with effective thermoelectric transformation reported from bulk materials has definite benefits to the practical application compared to nanomaterials. In this work, a nanostructure integrated macroscale thermoelectric chip, that is an alloyed band gap gradient macroscale chip (1.0 cm × 2.0 cm) composed of CdSSe nanowires, has been proven as an excellent thermoelectric generator for the first time. A high Seebeck coefficient of -152.4 μV/K and the average output voltage of 10.8 mV are obtained after optimizing the electrode patterns and distance between electrodes. More interestingly, upon illumination by white light from a xenon lamp, a photo-thermoelectric output voltage is greatly elevated to 45 mV due to the high concentration of photogenerated carriers. The CdSSe thermoelectric chip also shows good repeatability and high stability with a relative error of <6%. No study on the thermoelectric performance of such an alloyed band gap gradient macroscale chip is mentioned before. The results illustrate a bright avenue to realize a type of light-modulated macroscale thermoelectric chips by nanostructure, allowing such kinds of CdSSe chips to be used to generate electric energy in the near future.

Comparative Study of Triboelectric Nanogenerators with Differently Woven Cotton Textiles for Wearable Electronics

A comparative study of the electrical performance of triboelectric nanogenerators (TENGs) with plain- and 2/1 twill-woven cotton textiles was conducted. Furthermore, the microstructures of the cotton fiber surfaces were examined to understand the fundamental mechanical interaction among the cotton fibers in the TENGs. The TENG with 2/1 twill-woven cotton textiles exhibited higher output voltages compared to that with plain-woven cotton textiles. The difference in the output voltage between the two types of TENGs resulted from the difference in triboelectric charge generation between the constituent cotton textiles. The higher output voltage of the TENG with 2/1 twill-woven cotton textiles was attributed to the higher density in triboelectric interactions among the cotton fiber molecules.

Significantly Enhanced Energy-Harvesting Performance and Superior Fatigue-Resistant Behavior in [001]c-Textured BaTiO3-Based Lead-Free Piezoceramics

Energy-harvesting utilizing piezoelectric materials has recently attracted extensive attention due to the strong demand of self-powered electronics. Unfortunately, low power density and poor long-term stability seriously hinder the implementation of lead-free piezoelectrics as high-efficiency energy harvesters. For the first time, we demonstrate that tailoring grain orientations of lead-free ceramics via templated grain growth can effectively produce ultrahigh power generation performance and excellent endurance against electrical/mechanical fatigues. Significantly improved fatigue resistance was observed in (Ba_0.94Ca_0.06)(Ti_0.95Zr_0.05)O₃ grain-oriented piezoceramics (with ∼99% [001]_c texture) up to 10⁶ bipolar cycles, attributed to the enhanced domain mobility, less defect accumulation, and thus suppressed crack generation/propagation. Interestingly, the novel energy harvesters, which were developed based on the textured ceramics with high electromechanical properties, possessed ∼9.8 times enhancement in output power density compared to the nontextured counterpart while maintaining stable output features up to 10⁶ vibration cycles. The power densities, which increased from 6.4 to 93.6 μW/mm³ with increasing acceleration excitation from 10 to 50 m/s², are much higher than those reported previously on lead-free energy harvesters. This work represents a significant advancement in piezoelectric energy-harvesting field and can provide guidelines for future efforts in this direction.