A reversible electrochemical nanosyringe pump and some considerations to realize low-power consumption

An electrochemical syringe pump was fabricated by micromachining. Two sets of thin-film three-electrode systems for actuation and sensing were formed on a glass substrate, whereas a microflow channel and a microcontainer for the internal electrolyte solution were formed on a silicon substrate. Hydrogen gas produced or consumed on a platinum black working electrode was used as a working medium. The rates of pumping for flushing and sampling could be varied by adjusting the potential of the working electrode at appropriate values to reduce and oxidize the related species. As a result, bi-directional pumping could easily be realized. During pumping repeated up to 20 times, the deviation of the pumping rates was distributed within 7% of the respective averages. The function of the micropump incorporated in a system was tested using a solution containing Cu2+ ions and a distinct current increase accompanying the reduction of the ions was observed following the sampling. When the goal is to reduce power consumption, the material used for the auxiliary electrode is critical and Ag/AgCl was considered to be a good alternative for a platinum auxiliary electrode.