Fabrication Of Polycarbonate Microfluidic Devices Using Solvent Bonding With Hot Embossing

Thermoplastic microfluidic devices have been a focus of growing interest in microfludic analysis in recent years because of their optical transparency, low cost and ease of fabrication. In this thesis, a solvent bonding with hot embossing method was developed for the fabrication of polycarbonate microfluidic chips. Electrophoretic separation of Cy5dye was obtained in the polycarbonate chip with diode laser induced fluorescence detection.The channel networks were formed through hot embossing with microfabricated silicon and nickel master, and brass wire. The temperature, pressure and time for hot embossing were optimized in the experiments. CCD and SEM images of microchannels and the cross section of channels were given to show the effectiveness of the procedure.Acetonitrile was applied in solvent bonding because it can partly dissolve polycarbonate materials. The reaction time, standing time, bonding temperature, pressure and dwell time on the bonding process were investigated. Polycarbonate chips were enclosed using solvent bonding with hot embossing at78-81℃, far below the glass transition temperature (150℃) of polycarbonate material. The microchannels printed by silicon master in the substrate were138.1μm in top width,70.9μm in bottom width and44.8μm in depth. The microchannels (n=7) enclosed by solvent bonding were136.2μm in average top width,69.9μm in average bottom width and43.3μm in average depth. Only1.5μm difference in depth was checked in bonding procedure. CCD and SEM images of the cross section of chips were given to show the effectiveness of bonding with less distortion.The average shear stress of2.66MPa for polycarbonate chips was higher than the (1.0±0.4)×103kPa reported by a literature. The average tensile stress of0.99MPa was higher than the0.55MPa reported by a literature. Higher shear stress and tensile stress were gived to show the high bonding intensity for polycarbonate devices using solvent bonding with hot embossing. The performance of the polycarbonate devices was demonstrated in6electrophoretic separations of Cy5with a fluorescence intense precision of2.4%RSD, a migration time precision of1.6%RSD and an efficiency of1.1×104plates/m. The simple solvent bonding with hot embossing method can be used to fabricate small batches of polycarbonate devices for research purposes in common chemical labs.