Electro-thermal micro-pumps: exploiting structural polarizations at smeared interfaces

M. Stubbe, J. Gimsa
University of Rostock, DE

Keywords: electro-thermal micro-pumps, structural dispersion, volume force, lab-on-chip-systems

Summary:

Various designs for new AC electro-thermal micro-pumps (ETµPs) are present which exploit AC electro-kinetic forces acting on smeared charges in the bulk of fluids in the presence of a temperature gradient. Measurements of the pump flow velocity were consistent with finite-element method simulations and an analytical model. The advantages of the ETµP principle are the absence of moving parts, the opportunity to passivate all the pump structures, homogeneous pump channel-cross sections reducing the risk of the channel clogging by debris, force plateaus in broad frequency ranges as well as a reversal of the pump direction in dependence on the driving frequency. The operating frequencies ranging from kHz to GHz avoid electrolytic processes and electrode deterioration. In some designs, an integrated heating element allows the temperature gradient to be adjusted. The integration of additional inductances allows for an increase of the pump velocity at low AC-field voltages at resonance conditions. This and the usable conductivity range of the pumping medium from extremely low to above physiological values predestine ETµPs for the integration in biological analysis systems such as lab-on-chip systems. A further miniaturization of the pumps is also viewed as quite feasible.