Thesis (Ph.D.)--Chulalongkorn University, 2007

In this work, the development of material to fabricate lab-on-a-chip devices for biomedical applications is demonstrated. The property of different type of polymers: poly(dimethylsiloxane) (PDMS) and thermoset polyester (TPE) microchips were investigated. The PDMS chips were used to detect carbohydrate and thiol compounds in plasma samples. The results indicated that PDMS microchips suitable for clinical testing. The effect of layer-by-layer polyelectrolyte multilayer (PEM) coatings on the velocity and direction of electroosmotic flow (EOF) and the separation efficiency of PDMS microchips was studied using different polymer structures and different deposition conditions. The use of polyelectrolyte coatings generated a consistent EOF depending on the polymer structure and improved separation efficiency when compared to unmodified PDMS microchips. Thermoset Polyester (TPE) was prepared as an alternative material for microchip capillary electrophoresis with electrochemical detection (MCE-EC). TPE microchips were characterized in their native, plasma-oxidized, and PEM-coated forms. TPE microchips provided higher separation efficiencies compared to PDMS microchips, even though fabrication of TPE microchips is still very simple. The EOF of native and plasma-treated TPE microchip was higher and more consistent as a function of pH than the EOF of PDMS microchip. The TPE microchip was used to quantify biologically important compounds.