Non-photolithographic plastic-mold-based fabrication of cylindrical and multi-tiered poly(dimethylsiloxane) microchannels for biomimetic lab-on-a-chip applications

Abstract

To overcome the limitations of conventional lithography for generating cylindrical and multi-tiered microchannels, we demonstrate a facile and alternative route for non-photolithographic fabrication of plastic molds via micro-milling combined with hot embossing. First, semi-cylindrical negative channels were engraved on poly(methylmethacrylate) (PMMA) using a ball mill, and the obtained semi-cylindrical negative channel structure was transferred onto poly(ethyleneterephthalate) (PET) via hot embossing performed at a temperature intermediate between the glass transition temperature (T_g) values of the two thermoplastics. In this way, a positive semi-cylindrical channel structure was formed on the PET without distorting the original patterns on the PMMA. The PET mold with positive structures was then replicated onto poly(dimethylsiloxane) (PDMS) to produce negative semi-cylindrical channels, and by aligning two identical PDMS replicas, a cylindrical microchannel with a completely circular cross section was formed. Second, multi-tiered channel structures were readily obtained by controlling the depths of the microchannels in the micro-milling process. The effectiveness of the fabricated cylindrical and multi-tiered microchannels was evaluated by constructing a microvascular network and human liver sinusoid structure as proof-of-concept experiments. The simple fabrication and high precision in the resulting structures will pave the way for the construction of disposable biomimetic Lab-on-a-Chip (LOC) platforms with low manufacturing cost in a simple and facile manner feasible for mass production.