Author Description

Whenever a microfluidic device is fabricated or being utilized, i.e., when bio-particles deposit and adhere onto the microchannel wall, it is inevitable to introduce a relatively rough surface structure on the microchannel wall. Consequently, the fluids flowing behaviours and the associated mass transporting behaviours through the microchannels are affected. Many researchers are currently working on the influences of the surface structures on the electrokinetics in microchannels, and the interests of manipulating surface characteristics to obtain specific functional performance of microfluidic devices are keeping increasing. In the present thesis, a series of theoretical and experimental investigations were conducted for the complicated transport phenomena in designed microchannels in which uniformly distributed 3D prismatic elements were deliberately fabricated on the microchannel walls. Based on the above investigating results, several numerical models were developed and verified, respectively. For pressure driven flow, firstly, the flow resistance created by the 3D prismatic elements on the microchannel walls was quantitatively studied for both thin and thick electrical double layer (EDL) situations, and then the influence of the surface structure on ion transport through microchannels under pressure driven flow was illuminated. For electroosmotic driven flow, the influences of both the homogeneous and the heterogeneous surface structures on the flow behaviours and sample transport phenomena in microchannels were theoretically and experimentally investigated, respectively. Understandings from the above studies were successfully employed to instruct the enhancement of the concentration gradient in a concentration gradient generator.