Microinjection molding of plastic microfluidic chips including circular microchannels



In this study, a microfluidic chip prototype having circular microchannels was replicated by microinjection molding process, employing a modularized and sectioned micromold system (MSMS). In the viewpoint of microfluidic manipulation, a microchannel with circular cross-section shows several advantages over a conventional rectangular and/or square microchannel. To achieve a mass production of the microchannels with circular or round cross-sections, the micromold was designed and fabricated based on the concept of MSMS. It consisted of several micromold modules, each having half-circular cross-sectional microstructures on its one-side surface. The modules were precisely manufactured by a deep X-ray lithography using a synchrotron radiation and a subsequent nickel electroforming process. Then, the MSMS for a microinjection molding process was constructed by assembling the nickel modules. After the molding of plastic plate with open microchannels of half-circular cross-section, a thermal bonding of microinjection-molded plates was carried out to produce the microfluidic chip prototype including the circular microchannels. Observation of the surface quality, measurement of cross-sectional profiles, and microfluidic test were carried out, which verified the usefulness of the present fabrication process. POLYM. ENG. SCI., 54:42–50, 2014. © 2013 Society of Plastics Engineers