3D printing and laser annealing of conductive metallic inks without supports
May 23, 2016 | 08:00
3D printing and laser annealing of conductive metallic inks without supports could lead to customized electronic and biomedical devices. The method can produce not only sweeping curves and spirals but also sharp angular turns and directional changes written into thin air with silver inks, opening up near limitless new potential applications in electronic and biomedical devices that rely on customized metallic architectures.
The increasing demand for flexible, wearable electronics, sensors, antennas and biomedical devices has led a team at Harvard’s Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences (SEAS) to innovate an eye-popping new way of printing complex metallic architectures – as though they are seemingly suspended in midair. This laser-assisted direct ink writing method allows microscopic metallic, free-standing 3D structures to be printed in a single step without auxiliary support material.
The ink composed of silver nanoparticles is sent through a printing nozzle and then annealed using a 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. In this way, tiny hemispherical shapes or spiral motifs 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. Localized laser heating enables electrically conductive silver wires to be printed directly on low-cost plastic substrates.