All-in-One Piezo-Triboelectric Energy Harvester Module Based on Piezoceramic Nanofibers for Wearable Devices

Abstract

An all-in-one energy harvester module comprising a top piezoelectric layer, a bottom piezoelectric layer, and a middle triboelectric layer was fabricated based on flexible piezoceramic nanofibers to serve as a power source for wearable devices. The top and bottom piezoelectric layers were manufactured by modularizing electrospun piezoceramic nanofibers with an interdigitated electrode, and the energy harvesting characteristics were maximized by laminating the single modules in z-axis array arrangements. The triboelectric layer was manufactured by attaching polydimethylsiloxane on both sides of an electrode layer, and the energy harvesting characteristics were controlled according to the surface roughness of the triboelectric modules. The output voltages of the individual energy harvester modules of the all-in-one module were individually or integrally measured by hand pressing the lower and upper parts of the module. The all-in-one energy harvester module generated a maximum voltage (power) of 253 V (3.8 mW), and the time required to charge a 0.1 μF capacitor to 25 V was 40 s. The results of a simulated energy harvesting experiment conducted on the all-in-one energy harvester module showed that 42 LED bulbs arranged in the shape of the “KICET” logo could be turned on in real time without charging, and a mini fan consuming a power of 3.5 W was operated after charging a 10 μF capacitor for 250 s. This work shows the potential of the all-in-one module as an ecofriendly flexible energy harvester for operating wearable devices.

Impact-Driven Energy Harvesting: Piezoelectric Versus Triboelectric Energy Harvesters

“…TEH may be a better alternative for the future because the costs of triboelectric materials were much lower than the costs of piezoelectric materials. Future work can be on investigating and designing multiple triboelectric material strips in a generator to boost output power or an investigation of a hybrid design [ 59 , 60 ] to take full advantage of the strengths of both types of electricity-generating materials.…”

Energy Harvesting and Storage with Soft and Stretchable Materials

“…Besides, when these devices are used individually, a portion of ambient energy goes unharvested. [349] For example, when a solar energy harvester is used, body heat, [351,352] biofuel, [353] biomechanical energies [354][355][356] go unutilized. [349,357,358] Thus, integrating them into hybrid devices can maximize the ambient energy utilization providing a robust and reliable way to harvest energy.…”

Flexible Electronics: Status, Challenges and Opportunities

“…Some of the strategies that have been employed rely on exploiting the forces on the ambient like thermal gradients, for development of thermoelectric harvesters (Peng et al, 2019;Zhao et al, 2019); kinetic energy in the form of vibrations or mechanical strain, for piezoelectric harvesters (Hwang et al, 2015;; and finally, charging processes during friction, for triboelectric harvesters (Fan et al, 2012;Wen et al, 2018). Even though some barriers regarding the overall efficiency of these devices, like the poor output voltages and current densities of a single harvester; have been surpassed by designing hybrid systems composed of combinations of two of the three systems listed above (Kumar et al, 2019;Ji et al, 2020); some of the challenges persist, for instance: complexity of structure design, poor durability over long term exposure to repeated mechanical operation, relatively expensive fabrication process that limits large-scale production, and selection of the adequate materials in terms of mechanical and electrical properties (Qian and Kang, 2018). In addition to that, the harvesters are desired to be highly flexible so that they can easily be mounted on curved, soft surfaces in order to avoid discomfort for the user (Kim et al, 2018).…”