Patent ID: 8715531

Claim:
An actuator comprising (i) a driving electrolytic solution containing an anion, wherein the electrolyte solution comprises water as a solvent, and the anion is a fluorine-containing ion derived from a strong acid and, (ii) an actuator element containing a conductive polymer doped with a dopant, the conductive polymer being expanded and contracted when electrically oxidized and reduced in the driving electrolytic solution, the dopant is an aromatic sulfonate ion free of fluorine, the conductive polymer contains a 5-membered heterocyclic moiety as a repeating unit, and at least part of the 5-membered heterocyclic moieties has a carbonyl group when the conductive polymer is in an oxidized state, wherein in the oxidized state, the conductive polymer is a polymer having the following structural formula (1): wherein each portion marked with a black circle (•) is a radical portion, each portion marked with a plus sign (+) is a positively-charged portion, each A is an anion, each portion marked with a minus sign (−) is a negatively-charged portion, and the dashed line represents that n electrons are delocalized in the conjugate structure.