A poly-methylmethacrylate electrophoresis microchip with sample preconcentrator

A micro structure on poly-methylmethacrylate (PMMA) for sample concentratio n and electrophoresis was fabricated. This microfabricated structure was ab le to increase the detection signal and lower the amount of sample used in electrophoretic analysis. The thin-film electrode located at the T-intersec tion of the sample injection and separation channels provides the current p ath for the injection channel, but restrains the DNA molecules from passing through. This can accumulate DNA molecules and increase the concentration before performing the electrophoretic analysis. This microstructure was fab ricated using krypton fluoride (KrF) excimer laser photo-ablation and fusio n bonding techniques. The excimer laser photo-ablation performs rapid proto typing with great flexibility in design changes. The PMMA material is much cheaper than other materials, for example glass and silicon, used in capill ary electrophoresis and concentration. The applied electrical field was 300 V cm(-1) for the DNA concentration in this microstructure. Experiments sho w that the DNA concentration was saturated within 200 s after the DNA molec ules first reached the injection tee, The DNA fragments can be concentrated up to five times greater than samples without a concentrator at the inject ion tee, The separation results also demonstrated that the detected signal intensities of the separated DNA fragments in the tee-type chip with a samp le preconcentrator were five times greater than that obtained in a conventi onal cross-type capillary electrophoresis chip with an identical initial sa mple concentration.