Injection moulding of micropillar arrays: a comparison of poly(methyl methacrylate) and cyclic olefin copolymer

Abstract Injection moulding of micropillar arrays offers a fast and inexpensive method for manufacturing sensors, optics, lab-on-a-chip devices, and medical devices. Material choice is important for both the function of the device and manufacturing optimisation. Here, a comparative study of poly(methyl methacrylate) (PMMA) and cyclic olefin copolymer (COC) injection moulding of micropillar arrays is presented. These two polymers are chosen for their convenient physical, chemical, and optical properties, which are favoured for microfluidic devices. COC is shown to replicate the mould’s nano/microstructures more precisely than PMMA. COC successfully forms a micropillar array (250 mm diameter; 496 mm high) and closely replicates surfaces with nano-scale roughness (30–120 nm). In the same moulds, PMMA forms lens arrays (not true pillars) and smoother surfaces due to the incomplete filling for all parameters studied. Thus, COC offers finer structural detail for devices that require micro and nano-structured features, and may be more suited to injection moulding microfluidic devices.