Fabrication and characterization of a multi-stage electroosmotic pump for liquid delivery

The objective of the study described here was to explore the possibility of constructing a multi-stage electroosmotic pump (EOP). The 1–3-stages EOP have been fabricated using 10 cm×320 μm i.d. 2 μm porous silica particles packed-columns, fused-silica capillaries and stainless electrodes and their performances were characterized. When the power supply was connected to the electrodes of the pumps in parallel, compared with the 1-stage EOP, the out pressures of the 2- and 3-stage EOP were about 2- and 3-fold increase, respectively, and the flowrates of the 2- and 3-stage EOP were identical with that of the 1-stage EOP, at the same driving voltage. The multi-stage EOP, i.e., the n-stage EOP could be constructed using n packed-columns, n−1 narrow bore capillaries and n pairs of electrodes connected in series. When the counter flow in the capillaries FCON was regulated to be negligible, the output pressure PEOP (n) of n-stage EOP was n× PEOP(1) of 1-stage EOP with the flow rate unchanged at the same driving voltage, which demonstrated a potential application on a chip as a microfluidic component.