A Nonmechanical, Membrane-Based Liquid Pressurization System

Nonmechanical pumping of liquids is of key importance for applications ranging from biomedical lab-on-a-chip systems to morphing mechanical structures. In this paper, we report a new, reversible micropumping and pressurization system, with no moving parts, that uses only modest external power. This new "e-pump" operates via a type of electro-osmosis (EO) in which a charge imbalance is created electrochemically across a cation-selective membrane, cations migrate to balance the charge, and solvent is transported across the membrane, along with the mobile cation. No gas is produced in this electrokinetic pumping system, so only liquids are involved in pumping and pressurization. In this proof-of-concept study, an aprotic solvent (dimethylformamide) was chosen to select the specific cation that is migrating (tetrapropylammonium ion). To date, pressures up to 23 atm have been successfully demonstrated.