Long-term stable electroosmotic pump with ion exchange membranes

We present the design, fabrication and test of a novel inline frit-based electroosmotic ( EO) pump with ion exchange membranes. The pump is more stable than previous types due to a new flow component that ensures a controlled width of the diffusion layer close to the ion exchange membranes. The pump casing is constructed in polymers while the EO active part, the frit, is made in a nanoporous silica. The pressure capability of the pump is Delta p(m)/Delta V = 0.15 bar V-1. The flow rate to current ratio is Q(m)/I = 6 mu L min(-1) mA(-1). This translates to Delta p(m) = 4.5 bar and Q(m) = 6 mu L min(-1) at Delta V = 30 V. The pump has been tested with four different buffer concentrations. In order to investigate day-to-day reproducibility each Q - p pump characteristic has been recorded several times during hour-long operation runs under realistic operating conditions.