Electroosmotically Induced Hydraulic Pumping with Integrated Electrodes on Microfluidic Devices

Electroosmotic manipulation of fluids was demonstrated using thin metal electrodes integrated within microfluidic channels at the substrate and cover plate interface. Devices were fabricated by photolithographically patterning electrodes on glass cover plates that were then bonded to polymeric substrates into which the channels were cast. Polymeric substrates were used to provide a permeable membrane for the transport and removal of gaseous electrolysis products generated at the electrodes. Electroosmotic flow between interdigitated electrodes was demonstrated and provided electric field-free pumping of fluids in sections of the channel outside of the electrode pairs. The resultant pumping velocities were shown to be dependent on the applied voltage, not on the applied field strength, and independent of the length of the electroosmotically pumped region.