Invisible silver tracks produced by combining hot-embossing and inkjet printing

Hot embossed features are prepared by pushing customized and standard silicon calibration gratings, known as masters, into either polystyrene or polycarbonate, which are kept above their glass transition temperatures. A droplet of a silver nanoparticle ink is then dispensed over one of these as-formed grooves using an inkjet printer. The ink fills the grooves as a consequence of capillary forces and is observed to form tracks with a uniform width. The tracks are described as 'invisible' on account of having widths ranging from 5 to 15 mu m. Wider tracks can be produced by dispensing more droplets and tracks with different morphologies can be produced by using different masters. Several as-prepared features are thermally treated to produce conductive silver tracks. The conductivity of the tracks is found to be similar to 20% that of bulk silver.