A pump driven by a redox reaction of copper incorporated in poly(acrylic acid) gel was developed. It discharges and charges liquid at a level of a few hundred of picoliter per second upon expansion and contraction of the gel induced by reduction and oxidation of the copper, respectively. The pump discharged and charged equal volumes of 3.5 mu l water under potentiostatic control at -1.1 V vs. Ag/AgCl and at +0.8 V for 3 h each, showing excellent reversibility. Under galvanostatic control the volumes expelled and sucked were nearly controlled with the charge at steady states with flow rates of 3 x 10 pl s(-1) for the expelling and 1.6 x 10(2) pl s(-1) for the sucking. Further, changes in copper distribution in the pump upon its redox reaction were evaluated with energy dispersive X-ray spectroscopy (EDS). (C) 2016 The Electrochemical Society. All rights reserved.