Probing zeta potential of glass in electrolyte solutions by colloidal probe technique

On the microfluidic chip, the zeta potential is an important parameter dominating the direction and magnitude of the electroosmotic flow, electrophoresis and other electrokinetic transport phenomenon. However, the traditional methods for zeta potential measurement mainly work based on the indirect methods, which would introduce many errors. In this paper, a novel direct method based on AFM colloidal probe technique was developed to measure the zeta potential. Firstly, to simplify the theoretical model, the approaching speed of the colloidal probe, at which the hydrodynamic force could be neglected, was determined. Then by fitting the experimental data with the theoretical model, the zeta potential of glass in electrolyte solutions was directly calculated.