Linear electrochemical actuators with very large strains using carbon nanotube-redox gel composites

The synthesis and performance of novel redox-controlled gel actuators are described. The gels are constructed with quinone groups that can be reversibly oxidised or reduced, producing a marked change in the swelling of the gel. The use of highly sterically hindered quinones means that they can be polymerised directly without protection. Incorporation of carbon nanotubes produces good electrical conductivity in the gel and even swelling. By using a mechanical biasing element such as a spring doubling as the electrode, one-dimensional linear actuation can be realised, with strains over 40%. The device is robust over many cycles, and is capable of producing a force of 30 kPa at potentials less than 1 V.