Permeable superelastic liquid-metal fibre mat enables biocompatible and monolithic stretchable electronics.

Stretchable electronics find widespread uses in a variety of applications such as wearable electronics, on-skin electronics, soft robotics and bioelectronics. Stretchable electronic devices conventionally built with elastomeric thin films show a lack of permeability, which not only impedes wearing comfort and creates skin inflammation over long-term wearing but also limits the design form factors of device integration in the vertical direction. Here, we report a stretchable conductor that is fabricated by simply coating or printing liquid metal onto an electrospun elastomeric fibre mat. We call this stretchable conductor a liquid-metal fibre mat. Liquid metal hanging among the elastomeric fibres self-organizes into a laterally mesh-like and vertically buckled structure, which offers simultaneously high permeability, stretchability, conductivity and electrical stability. Furthermore, the liquid-metal fibre mat shows good biocompatibility and smart adaptiveness to omnidirectional stretching over 1,800% strain. We demonstrate the use of a liquid-metal fibre mat as a building block to realize highly permeable, multifunctional monolithic stretchable electronics.

Soft Hybrid Scaffold (SHS) Strategy for Realization of Ultrahigh Energy Density of Wearable Aqueous Supercapacitors.

Future wearable electronics requires safe and high-energy-density supercapacitors (SCs). Commercial SCs making use of organic electrolytes show high energy density, but the flammability of the electrolyte raises serious safety concerns. Aqueous SCs, on the other hand, are very safe, but the energy density is low due to the much narrower voltage window and the difficulty of fabricating thick electrodes. A new materials strategy named soft hybrid scaffold (SHS), which allows easy buildup of ultrathick electrodes made of 3D porous pseudo-material-modified carbon networks, is reported. The carbon network provides excellent mechanical stability and electric conductivity, the hierarchically porous structures ensure rapid ionic transport, and the pseudomaterials enlarge the electrochemical window. Asymmetric aqueous SCs using SHS electrodes show higher energy density than both commercial organic SCs and literature-reported aqueous SCs, with good cycle life and mechanical flexibility. The aqueous SC device is tailorable, waterproof, and fire-retardant, representing a high safety toward practical applications.