EFFECTS OF INJECTION SCHEMES AND COLUMN GEOMETRY ON THE PERFORMANCE OF MICROCHIP ELECTROPHORESIS DEVICES

A glass microchip column was fabricated for free-solution electrophore sis. The channels were wet chemically etched on a substrate using stan dard photolithographic techniques and were sealed using a direct bondi ng technique. Two methods of sample introduction are evaluated employi ng a cross-type channel geometry. With the preferred sample loading me thod, the volume of the sample plug can be accurately controlled and i s time independent, enabling a constant volume to be injected. The inj ection can be controlled electronically and does not induce any electr ophoretic mobility based bias. Separations were performed on a compact chip with a serpentine column geometry that has a 165-mm separation c hannel in an area of less than 10 mm x 10 mm. Band-broadening effects in a serpentine column pattern were studied.