A review of liquid metal patterning methodologies: principles, structures and applications

Gallium-based liquid metals uniquely combine metallic conductivity with fluidic compliance, making them ideal conductors for soft and stretchable electronics. However, patterning these materials requires managing the interplay between high intrinsic surface tension and native-oxide-mediated interfacial mechanics. The bare liquid metal penalizes the creation of new surface area during spreading, extrusion, or filling, whereas the spontaneously formed nanoscale oxide skin constrains liquid-like flow, reduces the effective interfacial energy at the metal/oxide interface, and stabilizes non-spherical geometries after shaping. This review addresses the central question of how to pattern liquid metals, categorizing strategies into direct methods, which shape the metal itself via interfacial, rheological, or phase-change control, and indirect methods, which rely on pressure-driven infusion into pre-formed microchannels. We discuss the extension of these techniques into the third dimension, enabling freestanding wires, simple 3D structures, lattice frameworks, and complex microarchitectures. These programmable structures translate geometric design into advanced function, powering applications from reconfigurable antennas and soft sensors to compliant bioelectronic interfaces and in vitro tissue models. Finally, we outline key challenges in reliability and system integration, highlighting that the future of liquid metal technology lies in closing the loop from material properties and processing to robust device performance.