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The triboelectric nanogenerator (TENG) is a newly arisen technology for mechanical energy harvesting from the environment, such as raindrops, wind, tides, and so on. It has attracted widespread attention in flexible electronics to serve as self-powered sensors and energy-harvesting devices because of its flexibility, durability, adaptability, and multi-functionalities. In this work, we fabricated a tubular flexible triboelectric nanogenerator (TF-TENG) with energy harvesting and human motion monitoring capabilities by employing polydimethylsiloxane (PDMS) as construction material, and fluorinated ethylene propylene (FEP) films coated with Cu as the triboelectric layer and electrode, serving in a free-standing mode. The tube structure has excellent stretchability that can be stretched up to 400%. Modifying the FEP films to obtain a superhydrophobic surface, the output performance of TF-TENG was increased by at least 100% compared to an untreated one. Finally, as the output of TF-TENG is sensitive to swing angle and frequency, demonstration of real-time monitoring of human motion state was realized when a TF-TENG was worn on the wrist. [ABSTRACT FROM AUTHOR]

We introduce an innovative designof a disk triboelectric nanogenerator(TENG) with segmental structures for harvesting rotational mechanicalenergy. Based on a cyclic in-plane charge separation between the segmentsthat have distinct triboelectric polarities, the disk TENG generateselectricity with unique characteristics, which have been studied byconjunction of experimental results with finite element calculations.The role played by the segmentation number is studied for maximizingoutput. A distinct relationship between the rotation speed and theelectrical output has been thoroughly investigated, which not onlyshows power enhancement at high speed but also illuminates its potentialapplication as a self-powered angular speed sensor. Owing to the nonintermittentand ultrafast rotation-induced charge transfer, the disk TENG hasbeen demonstrated as an efficient power source for instantaneouslyor even continuously driving electronic devices and/or charging anenergy storage unit. This work presents a novel working mode of TENGsand opens up many potential applications of nanogenerators for harvestingeven large-scale energy. [ABSTRACT FROM AUTHOR]

Harvesting thermoelectric energy mainly relies on theSeebeck effectthat utilizes a temperature difference between two ends of the devicefor driving the diffusion of charge carriers. However, in an environmentthat the temperature is spatially uniform without a gradient, thepyroelectric effect has to be the choice, which is based on the spontaneouspolarization in certain anisotropic solids due to a time-dependenttemperature variation. Using this effect, we experimentally demonstratethe first application of pyroelectric ZnO nanowire arrays for convertingheat energy into electricity. The coupling of the pyroelectric andsemiconducting properties in ZnO creates a polarization electric fieldand charge separation along the ZnO nanowire as a result of the time-dependentchange in temperature. The fabricated nanogenerator has a good stability,and the characteristic coefficient of heat flow conversion into electricityis estimated to be ∼0.05–0.08 Vm2/W. Ourstudy has the potential of using pyroelectric nanowires to convertwasted energy into electricity for powering nanodevices. [ABSTRACT FROM AUTHOR]