Authors: Y.-S. Leung Ki, R.B.M. Schasfoort, S. Sclautmann, Ph. Renaud and A. van den Berg
Affilation: EPFL, Switzerland
Pages: 544 - 547
Keywords: FlowFET, Electrokinetic effects, z-potential, microfluidics, double layer
Classical electrokinetic theory demonstrates that modu-lation of the z-potential at the shear plane can alter both the magnitude and direction of Electroosmotic Flow (EOF) induced in a microchannel at low driving field strengths. In the FlowFET, z-potential is modulated by applying a voltage VG ñ with respect to the driving field cathode ñ through the insulated side walls of the device. An analytical model based on overall charge neutrality is presented which predicts the z-potential as a function of VG. This is compared to values of shear plane z-potential extracted from EOF rate measurement data in a FlowFET. It is found that the model data and experimentally derived values for z-potential are within the same order of magnitude with good agreement between modeled and experimentally observed trends. Discrepancies are due to uncertainties related to experimental observation and lack of Stern layer modeling.