Injection moulding of ultra high aspect ratio nanostructures using coated polymer tooling

Replication-based nanofabrication techniques offer rapid, cost effective ways to produce nanostructured devices for a host of applications in engineering, biological research and beyond. In this work we developed a method to replicate ultra high aspect ratio (UHAR) nanopillars by injection molding with failure rates lower than one pillar in a thousand. We provide a review of the literature in which replication of difficult micro-and nanostructures is facilitated through the use of different tooling materials and surface coatings, before describing the non-adhesive surface coatings which we used to translate a previously developed technique from low to high aspect ratios. This development involved a systematic study of nine different surface coatings on polymer tooling initially patterned by nanoimprint lithography. Using this method we were able to produce injection moulded pillar-like nanostructures with aspect ratios of up to 20:1, more than 6 times that reported elsewhere in the literature for this type of feature.