Nanoimprint meets microfluidics: Development of metal wires from nanoparticle ink filled capillaries

Abstract

We demonstrate the use of prepatterned polymer substrates with μm-sized grooves to enhance the low resolution of additive methods such as inkjet and gravure printing by a factor of 10. This enables their use for low cost flexible electronics. Droplets of ink dispersions with <50 nm Ag nanoparticles with volumes in the nanoliter range were deposited on imprinted receiver pads and drawn into grooves by capillary action in an open-fluidics approach. Using this method, up to 2 mm long, 2 to 5 μm wide wires were created in U- and V-groove capillaries. The characterization of wire thickness before and after sintering revealed that ink supply of the already filled grooves continues from the reservoir during evaporation. By this, higher thickness is achieved than expected from the initial nanoparticle loading, and thus wires with sufficient electrical conductivity are formed. Keywords: Open-fluidics, Silver nanoparticles, Conductive ink, Self-confinement, Nanoimprint lithography, V-groove capillaries