Permeable and Patternable Super‐Stretchable Liquid Metal Fiber for Constructing High‐Integration‐Density Multifunctional Electronic Fibers

Abstract Stretchable electronic fibers are essential for soft electronics because of their small footprint, light weight, high compliance, and ease of integration. To date, the majority of stretchable electronic fibers are fabricated with solidly filled fiber substrates where the exchange of gas or liquid between the outer environment and the inner part of the fiber is largely inhibited, if not impossible. The nonpermeability largely wastes the inner volume of the fiber, especially for those sensor fibers. Here, a continuous fabrication of permeable and super‐stretchable liquid metal fibers for constructing high‐integration‐density and multifunctional electronic fibers are reported. The electronic fiber is comprised of self‐assembled porous elastomer fibers and multilayers of coaxially arranged liquid metal circuits patterned in the three‐dimensional space of the fiber matrix. The micron‐scale porous structure of the fiber matrix enables high permeability for effective materials/energy exchange between the surrounding environment and the components in different layers of the fiber. As a proof of concept, a stretchable multifunctional electronic fiber incorporated with three individual layers responsible for lighting, data transmission, and biochemical sensing, as well as an artificial neuron integrating multi‐modal sensing and electrical signal transmission capabilities, illustrating the potential of the fiber fabrication strategy for stretchable electronics applications is demonstrated.