Electrical activation of PAN-Pt artificial muscles

Abstract

Activated polyacrylonitrile (PAN) fibers are known to elongate and contract when immersed in caustic and acidic solutions, respectively. The change in length for these pH activated fibers is greater than 100% and are comparable in strength to human muscle, yet need of strong acids and bases for actuation has limited the use of PAN fibers as linear actuators or artificial muscles. Increasing the conductivity of PAN by depositing platinum within the fibers has allowed for electrical activation of PAN artificial muscles when it is placed in an electrochemical cell. The electrolysis of water in such a cell produces hydrogen ions at a PAN anode, thus locally decreasing the pH and causing the PAN muscle to contract. Reversing the electric field allows the PAN muscle to elongate. A 40% change in PAN muscle length in less than 10 minutes is observed when it is placed as an electrode in a 10 mM NaCl electrolyte solution and connected to a 20 volt power supply. These initial results indicate potential in developing electrically activated PAN muscles and linear actuators, which would be much more applicable than chemically activated PAN.