Liquid-Metal-Based Super-Stretchable and Structure-Designable Triboelectric Nanogenerator for Wearable Electronics

Abstract

The rapid advancement of intelligent wearable electronics imposes the emergent requirement for power sources that are deformable, compliant, and stretchable. Power sources with these characteristics are difficult and challenging to achieve. The use of liquid metals as electrodes may provide a viable strategy to produce such power sources. In this work, we propose a liquid-metal-based triboelectric nanogenerator (LM-TENG) by employing Galinstan as the electrode and silicone rubber as the triboelectric and encapsulation layer. The small Young's modulus of the liquid metal ensures the electrode remains continuously conductive under deformations, stretching to a strain as large as ∼300%. The surface oxide layer of Galinstan effectively prevents the liquid Galinstan electrode from further oxidization and permeation into silicone rubber, yielding outstanding device stability. Operating in the single-electrode mode at 3 Hz, the LM-TENG with an area of 6 × 3 cm produces an open-circuit voltage of 354.5 V, transferred short-circuit charge of 123.2 nC, short-circuit current of 15.6 μA, and average power density of 8.43 mW/m, which represent outstanding performance values for TENGs. Further, the LM-TENG maintains stable performance under various deformations, such as stretching, folding, and twisting. LM-TENGs in different forms, such as bulk-shaped, bracelet-like, and textile-like, are all able to harvest mechanical energy from human walking, arm shaking, or hand patting to sustainably drive wearable electronic devices.

Utilizing Room Temperature Liquid Metals for Mechanically Robust Silicon Anodes in Lithium‐Ion Batteries

“…The Si/LM/N‐rGO electrode showed lower reduced modulus and hardness which promote the flexibility of the composite. Galinstan has been reported to have a low Young's modulus enabling its use in applications which undergo high mechanical deformation such as wearable electronics . Furthermore, another study revealed that introduction of GO, results in decreased values for the Young's modulus and hardness as the porosity of the electrode increases, thereby, improving the flexibility of the electrode .…”

Liquid Metal–Based Soft Microfluidics

“…After a cell phone approached the wearable device, the generated radio frequency field builds up, rendering data communication via the LM antenna feasible: By this, pre‐encoded webpage/Apps were opened on the cell phone, as illustrated in Figure h. LM can be also integrated inside polymers into various structures like bulk shape, textile‐like, and bracelet‐like geometries that can harvest mechanical energy from the human motion, arm shaking and hand patting for powering of the other wearable electronics, as demonstrated by Yang et al n Figure k.…”

“…k) LM integrates inside polymers for harvesting of mechanical energy from the human motion, resulting in powering of the wearable electronics such as pedometer and mini‐calculator. Reproduced with permission . Copyright 2018, American Chemical Society.…”

Lightweight Liquid Metal Entity

“…And benefited from its melting point, such alloy can also realize convenient phase transition between solid and liquid at the range of room temperature. This is rather desired in many application fields such as flexible electronics, [ 1–3 ] additive manufacturing, [ 4,5 ] wearable devices, [ 6–8 ] biomedical practices, [ 9,10 ] exoskeleton systems, [ 11–13 ] and soft robotics. [ 14,15 ] However, the pretty large density of such metals (usually larger than 5 g cm −3 ) [ 16 ] turns out to be a major concern compared with those non‐metal materials like polymer, plastics, and wood, etc.…”