A new electro-osmotic pump based on silica monoliths

A high-pressure electro-osmotic (EO) micro-pump fabricated by a sol–gel process is shown to be potentially effective as a fluid-driving unit on chip-scale analytical systems. A silica monolithic matrix with a morphology of micron-scaled through pores was synthesized within the 100 m inner diameter (i.d.) fused-silica capillary of the micro-pump. The monolith bonds directly with the capillary wall such that frits with large pressure loss are unnecessary. This pump uses electro-osmotic flow to propel liquid solution with no moving parts. The Nafion® housing design in the cathode chamber prevents flow leakage into the electrode reservoir from the flow channel and hence maximizes the pressure build-up. It also eliminates electrolytic bubble interference from the flow channels and provides ionic channels for current p s t c c ©