Liquid Metal Electrodes: Material Properties, Interfacial Behavior, Fabrication, Performance, and Applications

Liquid metal electrodes (LMEs) combine metallic conductivity with fluid deformability, offering unique advantages for flexible electronics, sensing, biointerfaces, and energy devices. This review examines LMEs from an electrode-centered perspective, linking material composition and oxide-mediated interfacial behavior with fabrication, electrode architecture, performance, reliability, and application readiness. This review further highlights how electrode design and interfacial engineering govern practical electrical and mechanical performance. Emphasis is placed on gallium-based alloys and the dual role of their native oxide layer, which facilitates wetting, adhesion, and pattern stability but may also increase contact resistance and interfacial instability. Representative fabrication strategies are compared in terms of resolution, scalability, adhesion, and deformability, while electrode performance is benchmarked using conductivity or resistance, strain tolerance, cyclic reliability, electrical drift, and activation or self-healing requirements. Applications in flexible electronics, sensors, biomedical interfaces, and energy devices are discussed together with their technological maturity. No single fabrication route or electrode architecture is universally optimal, emphasizing the need for application-specific evaluation. Finally, key challenges in reproducible manufacturing, oxide regulation, contact degradation, leakage prevention, environmental durability, and lifecycle management are highlighted.