A narrow resonance bandwidth of an energy harvesters limits its response to the wide frequency spectrum in ambient environments. This work proposes an addition of a nonlinear restoring force applied to a triboelectric nanogenerator (TENG) to tune and broaden the resonance bandwidth. This restoring force is applied by permanent magnets at both sides of the slider and two external magnets. The noncontact strategy is adopted between the slider and the grating electrodes to avoid the wear of electrodes and energy loss caused by friction. The results show that compared with the linear system, the nonlinear noncontact TENG (NN-TENG) can increase the peak current from 6.3 μA to 7.89 μA, with an increment of about 25%, increase the peak power from 650 μW to 977 μW, increasing by about 50%, and increase the bandwidth from 0.5 Hz to 7.75 Hz, increasing by about1400%. This work may enable a new strategy to boost the bandwidth and output power of TENG through nonlinear oscillators.

Triboelectric nanogenerators (TENGs) represent a promising next-generation renewable energy technology. TENGs have become increasingly popular for harvesting vibration energy in the environment due to their advantages of lightweight, broad range of material choices, low cost, and no pollution. However, issues such as input force irregularity, working bandwidth, efficiency calculation, and dynamic modeling hinder the use of TENGs in industrial or practical applications. In this paper, the modeling process of the dynamical system of a TENG is reviewed from the perspective of energy flow. In addition, this paper reviews the main contributions made in recent years to achieve optimized output based on springs, magnetic forces, and pendulums, and introduces different ways to increase the bandwidth of TENGs. Finally, the main problems of TENGs in the process of harvesting vibration energy are discussed. This review may serve as a practical reference for methods to convert irregular mechanical input sources into optimized output performance toward the commercialization of TENGs.

Conventional titanium (e.g., bulk or thin films) is well-known for its relatively high mechanical strength, excellent corrosion resistance, and superior biocompatibility, which are suitable for biomedical engineering and wearable devices. However, the strength of conventional titanium often trades off its ductility, and their use in wearable devices has not been explored yet. In this work, we fabricated a series of large-sized 2D titanium nanomaterials with the method of polymer surface buckling enabled exfoliation (PSBEE), which possess a unique heterogeneous nanostructure containing nanosized titanium, titanium oxide, and MXene-like phases. As a result, these 2D titaniums exhibit both superb mechanical strength (6–13 GPa) and remarkable ductility (25–35%) at room temperature, outperforming all other titanium-based materials reported so far. More interestingly, we demonstrate that the 2D titanium nanomaterials also showed good performance in triboelectric sensing and can be used to fabricate self-powered, on-skin conformal triboelectric sensors with good mechanical reliability.