Laser-Assisted Method to 3D Print Metal in Midair

Researchers from Harvard University's Wyss Institute have developed a laser-assisted direct ink writing method that allows microscopic metallic, free-standing 3D structures to be printed in one step without additional support material. The researchers used used an ink made of silver nanoparticles, sending it through a printing nozzle and then annealing it using a precisely programmed laser that applies just the right amount of energy to drive the ink's solidification. The printing nozzle moves along x, y, and z axes and is combined with a rotary print stage to enable freeform curvature. Tiny hemispherical shapes, spiral motifs, and a butterfly made of silver wires less than the width of a hair can be printed in free space within seconds. The printed wires exhibit excellent electrical conductivity, almost matching that of bulk silver. The method can produce curves and spirals along with sharp angular turns and directional changes written into thin air with silver inks - opening up many potential applications in electronic and biomedical devices that rely on customized metallic architectures.