Millimeter-scale polymer ''fingers'' are reported, in which the volume
changes of the conjugated polymer polypyrrole that occur in response
to electrochemical reduction or oxidation are used to create electrica
lly controlled mechanical actuators. The short bilayer gold and polypy
rrole fingers in the Figure can be made to curl by reducing the polypy
rrole. The primitive fabrication technique used to make these fingers
points the way to the microminiaturization of these artificial muscles
.