| One of the most important electrical properties used for designing microfluidic device is the zeta-potential (zeta-potential), which is directly related to the strength and polarity of the electrical double layer (EDL) near a solid-liquid interface. The objective of this thesis is to design and construct a set-up capable of using the electroosmotic flow technique with the slope of current-time method to determine the magnitude of the zeta-potential of glass ad poly(dimethylsiloxane)- (PDMS) coated surfaces. Aqueous KCl and aqueous LaCl3 solutions, and microchannels with heights ranging from 200--300 mum were used in the study. The measured values of the zeta-potential are found to be independent of the channel size or the applied velocity, while they are strongly dependent on the surface properties of the test material, the electrolyte concentration, and the ionic valences. |
