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

Abstract

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.

Enhanced Differentiation of Human Embryonic Stem Cells Toward Definitive Endoderm on Ultrahigh Aspect Ratio Nanopillars

“…Here we fabricated arrays of 100 and 150 nm diameter PC pillars with heights between 500 and 2000 nm. [ 30 ] The corresponding spring constant for such nanopillars range from 5 to 1400 nN µm −1 -similar to that of the PDMS work by Fu et al [ 26 ] Moreover the softest pillars have an effective shear modulus similar to that of a commonly used acrylamide hydrogel. In the present work we demonstrate that these polycarbonate injection molded nanopillar surfaces can Fu et al [26] 2000 12 900 3 2.6…”

“…[ 30 ] In brief, nanofabricated master inlays were made by a combination of electron beam lithography and reactive ion etching. The inlays were then used in an injection molding process whereby 100-1000 s of substrates have been made for the experiments.…”

“…[ 30 ] The dimensions of the nanopillars and their equivalent mechanical properties are provided in Table 1 together with commonly used model systems from the literature.…”

Hydrogen silsesquioxane mold coatings for improved replication of nanopatterns by injection molding

“…The materials used to demonstrate heat retardation in an injection molding process have so far mainly been polymer-based [53]. These materials are suitable for prototyping or small-volume productions.…”

Injection Molding Micro‐ and Nanostructures in Thermoplastic Elastomers

“…The tool then opens and the newly formed bulk part is ejected to complete the automated process. Micro‐ and nanopatterning is achieved by patterning one or more of the cavity walls, often through the use of interchangeable inserts, sometimes referred to as stampers or inlays , which can be produced in a number of ways and are the subject of much of the literature in the field …”