Studies On Plasma Microseparation Technology Used In Microfluidic Chips

In order to meet the demands of integration of sample separation process in micro total analysis system(μTAS), a new method for several milliliters plasma separation is needed. In this dissertation microfiltration and centrifugation were deeply researched as two basic methods. Considering the particularity of plasma separation, the theoretical analysis, fabricating processes and experiments of micro-plasma-separator were developed.A stripe mesh microfilter was designed and produced on silicon substrate based on MEMS technology. Experimental results indicate that it can greatly remove 14μm diameter spheres from the suspension, however, the red blood cells can't be removed completely from whole blood with the microfilter because of their highly deformable ability.On the basis of capillary centrifugation, two centrifugal plasma-microseparation chips with different bonding methods were produced, which can separate plasma from milliliters of whole blood. The fabricating processes of the two chips were described, and the result of separation were measured through a set of experiments. The effects of surface properties of material, diameter of microchannel, parameter of centrifugation on the efficiency of plasma separation were discussed, and the effect of the roughness of silicon surface and the curing temperature of PDMS on the bonding strength were investigated.Furthermore, capillary valve and capillary pump were designed to control flows based on surface tension control technology in microchannel. Capillary pump was used to realize auto-injection of blood sample, and capillary valve can stop the fluid when it flows to the valve. Experiment of capillary valve shows it can be applied as passive valve under low pressure.