Long-term stable electroosmotic pump with ion exchange membranes

Abstract

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 Δp_m/ΔV = 0.15 bar V⁻¹. The flow rate to current ratio is Q_m/I = 6 µL min⁻¹ mA⁻¹. This translates to Δp_m = 4.5 bar and Q_m = 6 µL min⁻¹ at ΔV = 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.