Interfacial Electrochemical Polymerization for Spinning Liquid Metals into Core–Shell Wires

Abstract

Metal wires are of great significance in applications such as three-dimensional (3D) printing, soft electronics, optics, and metamaterials. Ga-based liquid metals (e.g., EGaIn), though uniquely combining metallic conductivity, fluidity, and biocompatibility, remain challenging to be spun due to their low viscosity, high surface tension, and Rayleigh−Plateau instability. In this work, we showed that EGaIn as a working electrode could induce the oxidization of EGaIn and interfacial electrochemical polymerization of electroactive monomers (e.g., acrylic acid, dopamine, and pyrrole), thus spinning itself from an opening of a blunt needle. During the spinning process, the high surface tension of EGaIn was reduced by electrowetting and electrocapillarity and stabilized by polymer shells (tunable thickness of ∼0.6−30 μm on wires with a diameter of 90−300 μm), which were chelated with metal ions. The polymeric shells offered EGaIn wires with an enhanced endurance to mechanical force and acidity. By further encapsulating into elastomers through a facile impregnation process, the resultant elastic EGaIn wires showed a combination of high stretchability (up to 800%) and metallic conductivity (1.5 × 10 6 S m −1 ). When serving as wearable sensors, they were capable of sensing facial expressions, body movements, voice recognition, and spatial pressure distributions with high sensitivity, good repeatability, and satisfactory durability. Machine-learning algorithms further assisted to detect gestures with high accuracy.

Lightweight Soft Conductive Composites Embedded with Liquid Metal Fiber Networks

“…To collect these LM fibers, interfacial electrochemical polymerization was used to encapsulate the LM. [45] Fabrication of LM microfibers below 100 μm remains a technical challenge to date. The large diameters of LM fibers produced by the existing methods limit their applications in e-textiles and soft conductive composites.…”

Current Status and Outlook of Low‐Melting‐Point Metals in Biomedical Applications

“…In recent years, EGaIn has developed broad application prospects in the fields of biomedicine, electronic equipment, and composite materials. [88,154,[161][162][163] EGaIn, with its good biocompatibility, has shown excellent performance in certain electronic devices. For example, Li et al successfully prepared a biocompatible liquid metal ink by encapsulating EGaIn nanodroplets into marine polysaccharide microgels and achieved high conductivity through sintering.…”

Water-Based Continuous Fabrication of Highly Elastic Electromagnetic Fibers

“…Room-temperature liquid metals (LMs) with fluidic nature and high conductivity (e.g., gallium–indium–stannum eutectic alloysEGaInSn: 3.1 × 10 6 S/m) have received considerable attention for building elastic conductive fibers. − Gallium-based LMs have been studied for elastic fibers through various approaches, including coating the elastic fibers with a layer of LM, − mixing LM to serve as a filler with elastomeric fibers, , and developing a core–sheath structure in fibers with LM as the core wrapped by an elastic sheath. − High metallic conductivity, conductive stability, and mechanical elasticity have been successfully achieved in LM-based elastic fibers. However, high surface tension and oxide skin formation in LMs limit their continuous processing, and the integration of magnetism with conductive stability in elastic fibers still remains challenging.…”