In this paper, we characterize polypyrrole-DBS-ClO4/tape bilayers with prevalent interchange of cations, while acting as macroscopic bending artificial muscles in aqueous solution. The electrochemical origin of their movement is described by linear equations deduced from the driving Faraday's laws. We demonstrate that the engineering parameters for macroscopic bending movement rates, the direction of the movement, described angles, and final positions of the electrochemical motors, are under control of the involved current, the direction of the current flow and the consumed charge, which means under Faradaic control of the conducting polymer composition. The linear equations describing both movement rate and position were obtained. The specific (per unit of polypyrrole weight in the muscle) driving current (A g(-1)), the specific driving charge (C s(-1) g(-1)) or the specific counter-ion composition variation (mol s(-1) g(-1)) are directly related to the actuator angular movement (rad s(-1) A(-1)), whatever the muscle dimensions or the working polypyrrole weight in the device. (C) 2010 Elsevier Ltd. All rights reserved.