Study On Fabrication And Analytical Application Of Poly(Methyl Methacrylate) Microfluidic Chips

A simple embossing method based on electric heating wires and a solvent bonding method of based on phase-changing agar hydrogel have been employed and developed for the fabrication of poly(methyl methacrylate)(PMMA) microfluidic chips. The noval methods have been optimized and the prepared PMMA microchips have been successfully employed in the electrophoresis separation and detection of analytes.In Chapter One, the background of microfluidic chip and PMMA microchip were briefly reviewed. Recent studies and developments on the fabrication of PMMA microchannel plate and the bonding technology of PMMA microchip were mainly discussed.In Chapter two, a simple method based on electric heating wires have been developed for the rapid fabrication of PMMA microfluidic chips for the purpose of electrophoresis in ordinary laboratories without the need for microfabrication facilities. Apiece of electric heating wire was stretched taut by clamping its ends to two tension springs. It was placed on a PMMA plate along the midline across its length. The blank PMMA plate and the wire were then sandwiched between two microscope slides under pressure. Subsequently, alternating current was allowed to pass through the wire to generate heat for the embossing of separation microchannel on the PMMA separation channel plate at room temperature. The injection channel on a PMMA sheet that was perpendicular to the separation channel was fabricated using the same procedure. Complete microchip was than obtained after the thermal bonding of the separation channel plate and the injection channel sheet. The electric heating wires used in this work not only generated heat but also served as templates for the hot embossing of the microchannels. The prepared microfluidic microchips have been successfully employed in the electrophoresis separation and detection of ions in a real sample in connection with contactless conductivity detection.In Chapter Three, a solvent bonding method based on phase-changing agar hydrogel has been developed for the fabrication of PMMA microfluidic chips. Prior to bonding, the channels and the reservoir ports on PMMA channel plates were filled with molten agar hydrogel that could gelate to form solid sacrificial layers at room temperature. Subsequently, PMMA cover sheets were covered on the channeled plates and1,2-dichlororethane was applied to the interspaces between them. The agar hydrogel in the channels could prevent the bonding solvent and the softened surface of the PMMA cover sheets from filling in the channels. After solvent bonding, the agar hydrogel in the channels and the reservoir ports was melted and removed under pressure. The sealed channels in the complete microchips had been examined by an optical microscope and a scanning electron microscope. The results indicated that high quality bonding was achieved at room temperature. The prepared microfluidic microchips have been successfully employed in the electrophoresis separation and detection of three cations in combination with contactless conductivity detection.In Appendix One, a CE-ED system was established for TCMs study. Details about the system, such as its configuration, apparatus parameters, installation, working conditions, and operation procedures, were introduced.In Appendix Two, A method based on far infrared-assisted solvent extraction (FIASE) and capillary electrophoresis-amperometric detection (CE-AD) has developed for the rapid determination of rutin and quercetin in Flos Sophorae Immaturus and esculin and esculetin in Cortex Fraxini. The effects of the irradiation time and the voltage applied on the infrared generator were investigated to acquire the optimum extraction conditions. It was demonstrated that far IR radiation substantially enhanced the extraction efficiency and the extraction time was significantly reduced from3h for conventional hot solvent extraction to6min for FIASE. The obtained extracts were subsequently analysed by CE-AD. The detection electrode was a300-1m-diameter carbon disc electrode at a detection potential of+0.90V (vs. saturated calomel electrode). The relation between peak current and analyte concentration was linear over about three orders of magnitude. The proposed method has been applied to determine the bioactive constituents in real samples...