Study On Miniaturized Analytical-Detection Systems Based On Microfluidic Chip

As the main research direction of micro total analysis system (μTAS), the microfluidic chips want to integrate the whole laboratory functions such as sampling, reaction, injection, separation and detection on a single chip, and to make the multiple analysis process efficient and convenient. Microchip-based analytical systems have turned to be the significant branch and front field of instrumental analysis. And the performances directly influence the detection sensitivity and validity, and become the key forμTAS to step into the individual or home diagnostics.In this dissertation, microfluidic chips were purposed to analyze clinical samples. The technologies about electrophoresis microchip were systemic studied, including chip microfabrication, on-chip experimental method investigation, and detection systems construction. The work was involved in the typical manipulations, such as the preconcentration, reaction, separation and detection. And the application of Microchip-based analytical systems in clinical diagnosis was realized.The topics of this dissertation are presented below:1. Research and development on microchip-based analytical systems was reviewed. Then new projects were carried out.2. Method for controlling sample plug was investigated. Based on the electric mode research, the microfluid was accurately controlled. The pinched injection and pull-back voltage mode improved the separation efficiency and detection sensitivity. Extrem pH and buffer additives mothod was used to minimize protein adsorption. The mixed standard proteins could be separated and deteted in 3~5min.3. Basing on microchip electrophoresis (MCE) and UV absorption theory, Clinical Urine UV-detection Instruments were designed and constructed. It was shown that MCE was a reliable analytic method for the diagnosis of proteinurias. The method was time-saving, convenient and cost-low. The detection limit reached 0.1mg/mL. 202 Urine samples from clinical cases were selected as target for microchip-based detection instruments, and the results were consistent with those from the routine electrophoresis system.4. Isoenzyme Fluorescent Detection Instrument was designed and constructed. A novel on-chip incubation and activity determination method for lactate dehydrogenase isoenzymes was developed here. The assay programs including injection,incubation and separation were high performed in the system. The detection limit reached 0.5 U/L.5. Electrokinetic trapping mechanisms was researched and applied to biological samples preconcentration. Therefore the detection limitation of the analytical systems could be improved. Nanostructures were fabricated with simple MEMS techniques. The concentration efficiency could be controlled through the adjustment of the nanostructure and buffer component.The dissertation showed that Microchip-based analytical systems were sample-saving, efficient, and convenient. And the instruments were easy to miniaturized, integrated and auto-controlled. Improved fluid controlling, preconctration and dedetection techniques, the systems could be reliable analytic methods for diagnosis.