Hierarchical Honeycomb-Structured Electret/Triboelectric Nanogenerator for Biomechanical and Morphing Wing Energy Harvesting

Flexible,compact,lightweight and sustainable power sources are indispensable for modern wearable and personal electronics and small-unmanned aerial vehicles(UAVs).Hierarchical honeycomb has the unique merits of compact mesostructures,excellent energy absorption properties and considerable weight to strength ratios.Herein,a honeycomb-inspired triboelectric nanogenerator(h-TENG)is proposed for biomechanical and UAV morphing wing energy harvesting based on contact triboelectrification wavy surface of cellular honeycomb structure.The wavy surface comprises a multilayered thin film structure(combining polyethylene terephthalate,silver nanowires and fluorinated ethylene propylene)fabricated through high-temperature thermoplastic molding and wafer-level bonding process.With superior synchronization of large amounts of energy generation units with honeycomb cells,the manufactured h-TENG prototype produces the maximum instantaneous open-circuit voltage,short-circuit current and output power of 1207 V,68.5μA and 12.4 mW,respectively,corresponding to a remarkable peak power density of 0.275 mW cm^(−3)(or 2.48 mW g^(−1))under hand pressing excitations.Attributed to the excellent elastic property of self-rebounding honeycomb structure,the flexible and transparent h-TENG can be easily pressed,bent and integrated into shoes for real-time insole plantar pressure mapping.The lightweight and compact h-TENG is further installed into a morphing wing of small UAVs for efficiently converting the flapping energy of ailerons into electricity for the first time.This research demonstrates this new conceptualizing single h-TENG device’s versatility and viability for broad-range real-world application scenarios.

Miura-origami-inspired electret/triboelectric power generator for wearable energy harvesting with water-proof capability

One of the critical issues for electret/triboelectric devices is the poor charge viability and stability in humid environments.Herein,we propose a new origami-inspired“W-tube”-shaped triboelectric nanogenerator(W-TENG)with two thin-film electrets folded based on Miura-origami.The Miura-origami fold is capable of transforming flat materials with large surface areas into reduced and compressed complex 3D structures with parallelogram tessellations.The triboelectric power generation components can thus be hermetically sealed inside the“W-tube”to avoid contact with the external humid environment.Furthermore,the elastic nature of the Miura-origami fold endows the proposed W-TENG device with excellent deformability,flexibility,and stretchability.Therefore,it is capable of harvesting kinetic energy from various directions and forms of movement,including horizontal pressing,vertical tapping,and lateral bending.The compact,light weight,and self-rebounding properties of the origami structure also make it convenient for integration into wearable devices.Various parameters of the W-TENG are intensively investigated,including the number of power generation units,original height of the device,acceleration magnitude,excitation direction,and water-proof capability.Triggered by hand tapping impulse excitation in the horizontal and vertical directions,the instantaneous open-circuit voltages can reach 791 V and 116 V with remarkable optimum powers of 691μW at 50MΩand 220μW at 35 MΩ,respectively.The outcomes of this work demonstrate the fusion of the ancient art of origami,material science,and energy conversion techniques to realize flexible,multifunctional,and water-proof TENG devices.