A poly-methylmethacrylate electrophoresis microchip with samplepreconcentrator

Abstract

A microstructure on poly-methylmethacrylate (PMMA) for sample concentrationand electrophoresis was fabricated. This microfabricated structure was able toincrease the detection signal and lower the amount of sample used inelectrophoretic analysis. The thin-film electrode located at theT-intersection of the sample injection and separation channels provides thecurrent path for the injection channel, but restrains the DNA molecules frompassing through. This can accumulate DNA molecules and increase theconcentration before performing the electrophoretic analysis. This microstructurewas fabricated using krypton fluoride (KrF) excimer laser photo-ablation andfusion bonding techniques. The excimer laser photo-ablation performs rapidprototyping with great flexibility in design changes. The PMMA material ismuch cheaper than other materials, for example glass and silicon, used in capillaryelectrophoresis and concentration. The applied electrical field was300 V cm-1for the DNA concentration in this microstructure. Experiments show that theDNA concentration was saturated within 200 s after the DNA moleculesfirst reached the injection tee. The DNA fragments can be concentrated up tofive times greater than samples without a concentrator at the injection tee.The separation results also demonstrated that the detected signal intensitiesof the separated DNA fragments in the tee-type chip with a samplepreconcentrator were five times greater than that obtained in a conventionalcross-type capillary electrophoresis chip with an identical initial sample concentration.