Inkjets + lasers = new precision 3D printing system

Printing butterflies is just one possibility for the new inkjet/laser system. (credit: Lewis Lab / Wyss Institute at Harvard University)

Customizable, wearable electronics open the door to things like heart-monitoring t-shirts and health-tracking bracelets. But placing the needed wiring in a complex 3D architecture has been hard to do cheaply. Existing approaches are limited by material requirements and, in the case of 3D writing, slow printing speeds. Recently, a research team at Harvard University developed a new method to rapidly 3D print free-standing, highly conductive, ductile metallic wires.

The new method combines 3D printing with focused infrared lasers that quickly anneal the printed nanoparticles into the desired architecture. The result is a wire with an electrical conductivity that approaches that of bulk silver.

3D printed conductive wires

The new 3D printing approach starts like a standard inkjet: concentrated silver nanoparticle inks are printed through a glass nozzle. The ink is then rapidly annealed by a focused infrared beam trailing the print stream by 100µm. This laser annealing process increases the density of the nanoparticles, transforming them into a shiny silver wire. The researchers demonstrated that its ability to print an array of silver wires with diameters ranging from the sub-micron up to 20µm through variation of a few key printing parameters.

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