A New Monolithic Electrokinetic Pump With Bubble-Less Design

An electrokinetic micro-pump fabricated by a sol-gel process has been designed which can be used as a robust fluid-driving unit on a chip-scale analytical system. An overall monolithic silica matrix with morphology of micron-scaled through pores was formed within 100-μm inner diameter fused silica capillary. This pump utilizes electroosmotic flow to propel liquid solution with no moving parts. The Nafion® house design in the cathode chamber separates the electrolytic bubble interference from flow channels. The maximum flow rate and maximum pressure generated by the pump are 3.0 μL/min and 3.5 atm, respectively, at 6 kV. The flow rate can be controlled in the range 200 nL-3.0 μL/min by adjusting applied electric filed. As the monolith is silica-based, this pump can be used for a variety of fluids, especially for organic solvents such as acetonitrile and methanol, without swelling and shrinking problems. These results indicate that the pump can provide sufficient pressure and flow for micro-total-analysis systems (μTAS).