Improvement And Characterization Of Micro-Nanofluidic Interface On Fused-Silica Capillary

Analytical measurement is one of the most frequent experimental activities in scientific research. One important development of analytical technology is the appearance of micro-TAS (Miniaturized Total Analysis System) which is based on microfluidics chip. With the development of micro-fabrication technique, preparation of channels in nanometer scale is possible, and a new research field termed as micro-nano-fluidics is formed. The establishment, characterization and applications of micro-nano-fluidics system remain to be hot issues.In the first chapter of this paper, in light of electrokinetic concentration in microchip capillary electrophoresis based on micro-nanofluidic effects, the theories, rectification effect, fabrication methods and applications of the system were reviewed.In the second chapter, the effect of voltage on the surface morphologyof the HF etched fused silica capillary was investigated by SEM. It is demonstrated that the applied voltage during etching not only functioned as an indicator of the end point, but also affected the surface morphology of etched capillary. The higher the voltage was the rougher the surface of the etched capillary. Ion transport through the micro-nano interface was investigated under different pH and ionic strength conditions. In300s,104times concentration was achieved with a negatively charged fluorescent probe under optimized conditions, and the reproducibility was good. The RSD of the peak hight is0.54%.In the third chapter, a new micro-nano interface was prepared by coating Nafion polymer on a capillary fracture. The width of the fracture was estimated based on the resistance measurement and a theoretical model of the fracture. The Nafion concentration was optimized for obtaining a transparent and homogeneous coating. The influoence of ion strength on the concentration polarization was investigated by microscope fluorescence imaging. The concentration efficiency with this new interface was preliminarily studied.This work provided more imformation on the micro-nanofluidic interface, which is important for further investigation in anlytical applications for low abuandant charged biomolecues.