Effects of Fabrication Process Parameters on the Properties of Cyclic Olefin Copolymer Microfluidic Devices

Abstract

Among the materials used for fabricating microfluidic devices, plastics have been increasingly employed in the past few years. Although several methods for fabricating plastic devices have appeared in the literature, reports typically indicate one set of conditions that yield functional devices; little data are available detailing how results are affected by their changes in the process variables. We report in this paper a systematic study of fabrication process parameters including compression rate, molding temperature, and the force used by a hydraulic press, as well as their effects on the device properties. Using cyclic olefin copolymers as the molding material, we found that the device thickness decreased when the molding temperature and compression force increased. Fidelity in the pattern transfer from a master to a device was confirmed by the reproduction of nanostructures and channel depth/ shape. Pattern transfer fidelity appeared to be independent of the molding temperature and compression force, at least in the range of conditions we investigated. Stress whitening (or crazing) on the device surface was found to be related to the molding temperature and the cooling rate of the mold/device assembly. The bond strength between the layers of a laminated device was determined to be a function of the lamination temperature. In addition, we demonstrated the utility of a plastic microfluidic device by separating proteins.[1678]

Bonding of thermoplastic polymer microfluidics

“…This feature, together with the relatively high bond strengths and overall simplicity of the approach, have made direct thermal bonding the most common method for sealing microfluidic chips. Thermal fusion bonding of various thermoplastics has been widely demonstrated, including PC Wang et al 2005;Park et al 2008;Shadpour et al 2007;Wang et al 2008), PMMA (Chen et al 2003;Arroyo et al 2007;Kelly and Woolley 2003;Liu et al 2008;Nie and Fung 2008;Nikcevic et al 2007;Sun et al 2006;Tan et al 2008;Yao et al 2005;Zhu et al 2007), and COC Bhattacharyya and Klapperich 2006;Riegger et al 2007;Tsao et al 2008;Steigert et al 2007;Fredrickson et al 2006;Olivero and Fan 2008). Direct thermal bonding of a wide range of polymers including polystyrene, nylon, polysulfone ) as well as polystyrene and copolyester ) have also been explored.…”

Dynamic coating for protein separation in cyclic olefin copolymer microfluidic devices

“…Plastic microfluidic devices are fabricated using the procedure described previously (Fredrickson et al 2006). Briefly, all patterns are designed using a CAD program (AutoCAD, San Rafael, CA) and fit on a standard 1 in.…”

“…Both of them will be referred to as COC, following the practice of international union of pure and applied chemistry (IUPAC), an organization recognized as the world authority on chemical nomenclature (Shin et al 2005). Cyclic olefin copolymer is a low-cost polymer that has high organic solvent resistance, minimum water adsorption, glass-like optical clarity, and low background fluorescence (Fredrickson et al 2006). Its glass transition temperature (T g ) ranges from 70 to 160°C, depending on the type of resin or film.…”

Two‐dimensional protein separation in microfluidic devices

“…Fan and co-workers created an array of microfluidic pseudo-valves for introducing different separation media, without cross-contamination, in both dimensions; the valves also allowed transfer of proteins from the first to the second dimension [46]. The two-layer device was fabricated from cyclic olefin copolymer, which is a low-cost polymer that has high organic solvent resistance, minimum water adsorption, glass-like optical clarity, and low background fluorescence [52]. The layout of the device is shown in Fig.…”