Graphene Electrode Powers Artificial Muscles

An electrode made of a single-atom-thick layer of carbon has been developed by researchers in South Korea to help make more robust artificial muscles.

Ionic polymer metal composites (IPMCs) are also known as artificial muscles. They are electro-active polymer actuators, changing in size or shape when stimulated by an electric field.

IPMCs have been deeply investigated for possible applications to robotics inspired by nature, for example, underwater vehicles propelled by fish-like fins, and in rehabilitation devices for people with disabilities.

IPMC actuators consist of a molecular membrane stretched between two metal electrodes. When an electric field is applied to the actuator, the ensuing movement and redistribution of ions in the membrane causes the structure to bend.

IPMC actuators are valued for their ability to mimic movements that occur naturally in the environment, low power consumption, as well as their ability to bend under low voltage.

But There is a Major Disadvantage

Cracks can propogate on the metal electrodes after a period of exposure to air and electric currents. This cracking can lead to the leakage of ions through the electrodes. The result is degraded performance.

Researchers are searching for a flexible, highly conductive, crack-free, and cost-effective electrode that can be used to construct a durable polymer actuator.

Now, researchers from the Korea Advanced Institute of Science and Technology have announced the development of a thin-film electrode based on a novel ionic polymer-graphene composite (IPGC).

Graphene is a single-atom-thick layer of carbon with exceptional mechanical, electrical and thermal properties.

The new electrodes have a smooth outer surface that repels water and doesn’t have apparent cracks, which makes them nearly impermeable to liquids. They also have a rough inner surface, which facilitates the migration of ions within the membrane to stimulate bending.

There are still multiple challenges and further research is needed to realise the full potential of the graphene-based electrodes and their subsequent commercialisation. In 2015, theesearchers plan to extend the bending performance of the actuators, and enhance ability to store energy and power.

Schematic: Ionic polymer-graphene composite (IPGC) actuator or “motor”. When an electric field is applied, the redistribution of ions causes the structure to bend. Credit: Korea Advanced Institute of Science and Technology