A low-voltage nano-porous electroosmotic pump

A low-voltage electroosmotic (EO) micropump based on an anodic aluminum oxide (AAO) nano-porous membrane with platinum electrodes coated on both sides has been designed, fabricated, tested, and analyzed. The maximum flow rate of 0.074 ml min−1 V−1 cm−2 for a membrane with porosity of 0.65 was obtained. A theoretical model, considering the head loss along the entire EO micropump system and the finite electrical double layer (EDL) effect on the flow rate, is developed for the first time to analyze the performance of the EO micropump. The theoretical and experimental results are in good agreement. It is revealed that the major head loss could remarkably decrease the flow rate, which thus should be taken into account for the applications of the EO micropump in various Lab-on-a-chip (LOC) devices. However, the effect of the minor head loss on the flow rate is negligible. The resulting flow rate increases with increasing porosity of the porous membrane and κa, the ratio of the radius of the nanopore to the Debye length.

This paper presents a low-voltage EO micropump based on an anodic aluminum oxide nano-porous membrane with platinum electrodes coated on both sides. Figure shows the correction factor, α, introduced to account for finite EDL effect on the flow rate of the EO micropump. Insets show the top and side SEM images of the porous membrane.Figure optionsDownload high-quality image (86 K)Download as PowerPoint slideResearch highlights
► Electrodes directly coated on both sides of a nano-porous membrane reduce the driving voltage for an EO micropump.
► Major head loss must be considered in the design and evaluation of an EO micropump.
► Flow rate increases with increasing porosity of the nano-porous membrane.
► EDL overlap dramatically reduces the flow rate in nano-porous membrane-based EO pumps.