3D micro-structures by piezoelectric inkjet printing of gold nanofluids

3D solid and pocketed micro-wires and micro-walls are needed for emerging applications that require fine-scale functional structures in three dimensions, including micro-heaters, micro-reactors and solar cells. To fulfill this demand, 3D micro-structures with high aspect ratios (>50:1) are developed on a low-cost basis that is applicable for mass production with high throughput, also enabling the printing of structures that cannot be manufactured by conventional techniques. Additively patterned 3D gold micro-walls and -wires are grown by piezoelectric inkjet printing of nanofluids, selectively combined with in situ simultaneous laser annealing that can be applied to large-scale bulk production. It is demonstrated how the results of 3D printing depend on the piezoelectric voltage pulse, the substrate heating temperature and the structure height, resulting in the identification of thermal regions of optimal printing for best printing results. Furthermore a parametric analysis of the applied substrate temperature during printing leads to proposed temperature ranges for solid and pocketed micro-wire and micro-wall growth for selected frequency and voltages. (paper)