EGaIn-based liquid-metal electrodes for electronic interfaces and contact engineering.

Liquid metals offer a unique combination of metallic conductivity and fluid-like deformability, but their practical implementation as electrodes requires precise control over dynamic and chemically active interfaces. This review examines eutectic gallium-indium (EGaIn) as a representative gallium-based liquid metal and analyzes how its native oxide skin, wetting behavior, reactive alloying, and contact mechanics govern electrical contact formation, interfacial stability, and device integration. Across electronic interfaces, bioelectrode systems, and semiconductor contacts, recent studies show that oxide engineering, interfacial chemistry, mechanical confinement, controlled activation, self-packaging, and low-damage metallization can transform liquid metals from soft conductors into reliable interface materials. These strategies enable conformal printed electrodes, stretchable and leakage-resistant interconnects, implantable and dry bioelectrodes, and low-thermal-budget contacts for fragile electronic materials. By organizing these advances within a unified interface-engineering framework, this review highlights the potential of liquid-metal electrodes as adaptive, programmable, and quantitatively controllable interfacial platforms for next-generation electronic and bioelectronic systems.