Electrowetting–tension synergy driven printing of 3D metal architectures on multiple planar and curved substrates

The fabrication of unsupported three-dimensional (3D) metal microstructures is essential for advanced electronic interconnects and three-dimensional circuitry. Low-melting-point alloys (LMPAs) are attractive for additive manufacturing due to their high electrical conductivity and low processing temperature; however, their high surface tension and surface oxide layer result in poor wettability and unstable deposition, limiting printing resolution and three-dimensional formability. Here, we report a printing technique for Field’s metal (FM) driven by the synergistic effect of electrowetting and tension. By dynamically regulating the wetting behavior between the FM and the substrate, stable extrusion through microscale nozzles is achieved, enabling controllable deposition. High-resolution two-dimensional (2D) patterns with line widths ranging from 20 to 200 μm can be printed over a wide speed window from 0.1 to >100 mm·s^-1, allowing flexible control of pattern dimensions. Enhanced wetting behavior improves the interfacial stability of the printed two-dimensional features during subsequent tension-driven three-dimensional construction, enabling resistance to localized detachment under tension. This stability ensures the reliable fabrication of three-dimensional structures on diverse substrates, particularly curved surfaces. Using this method, various unsupported 3D structures, including helical lines, microelectrode arrays, and spatial circuits, were fabricated on substrates with different curvatures, all of which exhibited excellent electrical conductivity (2×10⁴ S·cm^-1). The printed three-dimensional structures remain mechanically stable under inertial loading up to 0.5 g and structurally intact during thermal cycling from 0 to 65 ℃, demonstrating reliable performance for practical applications. These capabilities demonstrate the applicability of this technique for three-dimensional electrical interconnects, vertical conductive vias, wireless power transmission components, and spatially integrated electronic circuits.