Permeable, three-dimensional integrated electronic skins with stretchable hybrid liquid metal solders

The development of wearable and on-skin electronics requires high-density stretchable electronic systems that can conform to soft tissue, operate continuously and provide long-term biocompatibility. Most stretchable electronic systems have low-density integration and are wired with external printed circuit boards, which limits functionality, deteriorates user experience and impedes long-term usability. Here we report an intrinsically permeable, three-dimensional integrated electronic skin. The system combines high-density inorganic electronic components with organic stretchable fibrous substrates using three-dimensional patterned, multilayered liquid metal circuits and stretchable hybrid liquid metal solder. The electronic skin exhibits high softness, durability, fabric-like permeability to air and moisture and sufficient biocompatibility for on-skin attachment for a week. We use the platform to create wireless, battery-powered and battery-free skin-attached bioelectronic systems that offer complex system-level functions, including the stable sensing of biosignals, signal processing and analysis, electrostimulation and wireless communication. An electronic skin that connects rigid inorganic electronic components with a multilayered stretchy liquid metal fibre mat using a hybrid liquid metal solder can offer high integration density while remaining soft, permeable and biocompatible.