LAUSR

Abstract Lab on a chip technology requires exquisite control over key surface properties using mass manufacturing strategies. Here, we investigate the relationship between the surface roughness of a micromilled mould insert and that of an injection moulded poly (methyl methacrylate), PMMA, part. The choice of milling tool, feed rate, and radial depth of cut dimension was varied. The smallest roughness (arithmetic mean height) was ∼50 nm for the mould insert and ∼20 nm for the moulded PMMA part. The latter is comparable with cast PMMA and appears to be a lower limit for the conditions studied, irrespective of the insert roughness. Wettability measurements on the PMMA surfaces report a slight increase in hydrophilicity with increased roughness factor, qualitatively consistent with Wenzel’s prediction. Scanning electron microscopy and atomic force microscopy show that the PMMA surface roughness is dominated by replication of larger milling features, with very smooth interstitial regions. It is shown that well-chosen milling parameters for insert manufacture can reduce machine time without compromising the surface quality of the injection moulded parts.