Bending bilayer strips built from polyaniline for artificial electrochemical muscles

Electrically conducting conjugated polymers such as polyaniline (PANi) usually show gel properties with volume changes in the range 1-100% in response to some external stimuli. The bending beam method provides an effective and sensitive way to detect and make use of these volume changes. Bipolymer laminate strips (2.5*0.2 cm2), made of a PANi layer (10 mu m thick) and a substrate polyimide layer (45 mu m thick) bound together, were prepared. These strips bend, corresponding to volume changes in the PANi layer, during electrochemical redox of the PANi in aqueous solutions. The extension (<or=1.0 cm) and velocity (<or=48 cm min-1) of the movement of the strips can be controlled by applying appropriate potentials and currents. The authors obtained significant and reversible movement back and forth in seconds.