Design, analysis, and experimental performance of a novel micro-nozzle based liquid metal direct writing system

The use of liquid alloy micro-printing methods for stretchable conductors and sensors has become a hot topic of micromachining research because of its attractive properties. Due to the high surface tension and easy oxidation characteristics of liquid metal, it is difficult to be accurately processed. In this paper, a direct writing method based on micro-nozzles for Galinstan alloy is presented. In comparison with the existing liquid alloy printing methods, the size of metal drops is reduced to 83 μ m by utilizing its wettability with the substrate and self-made micro-nozzles with the accuracy of micro order in a range from 13 to 87 μ m inner diameter. This micro direct writing system was used to produce an array of alloy droplets, micro droplets and wires patterns, and a pile of alloy on account of the formation of the gallium-oxide layer which preserves their shapes. The diameter of droplets in an array is less than 83 μ m and the line width is as small as 83 μ m. This first demonstration of direct writing based on micro-nozzles provides a variety of liquid metal distribution strategies and improves the accuracy of alloy electronics. Also, attempts have been made to produce a vertical pile of droplets, by the shape protection of gallium-oxide skin. This method makes a good compromise between resolution, process simplicity, design flexibility, and fast delivery automaticity.