Microarray-integrated optoelectrofluidic system for biological assay

Abstract

This thesis presents the development of an integrated optoelectrofluidic system for biological assays based on a microarray format to overcome low reaction efficiency, a significant issue of surface-based sensing system. An analyte depletion problem commonly occurs in immunoassay systems where mass transport of target molecules depends on only diffusion manner, which causes a loss of assay performances. To improve the reaction efficiency, active mass transport of molecules at assay regions was generated by applying an optically-induced AC electrokinetic flow, resulting in an achievement of enhanced immunoassay results. To understand the optoelectrofluidic mass transport, I firstly investigated the effect of an optically-induced AC electroosmosis (ACEO) on focusing colloidal particles. Colloidal particles could be concentrated to a projected region thanks to the optically-induced strong convective flow. Based on these studies, I explored potential of the optoelectrofluidic technology to be effectively utilized in a microfluidic environment where mass transport is limited. Second, I proposed an optoelectrofluidic enhanced immunoreaction based on the optically-induced ACEO. Mass transport phenomena of molecules under the optoelectrofluidic system with a surface-based assay system were investigated by mathematical simulation studies and experiments using an immunoreaction set. The proposed system with an optically-induced convective flow could improve the reaction efficiency with a 2.18-fold enhancement under dynamic light patterns compared to the passive mode by overcoming the diffusion limitation problem. Finally, I presented a novel optoelectrofluidic immunoassay integrated with a microarray format. Multiple convective flows were generated on multiple spots of the microarray by an optical manner, which enhanced mass transport, resulting in a reduction of the reaction time from more than 30 min to 10 min with minimal sample consumption. Based on this enhancing effect, the microarray-integrated optoelectrofluidic system was applied in quantitative immunoassay. Furthermore, the application of multiplex immunoassay was demonstrated by simultaneous multiple protein detection.