Muscle-like flexible material can revolutionize prosthetics

June 3, 2016
According to a new study published this week in the journal Nature Chemistry, the muscle-like material is so flexible that the researchers didn’t have the proper equipment to stretch it far enough to reach its breaking point. Two members of the team responsible for the super-stretchy material physically stretched the material themselves,  eventually stretching a 1-inch portion to more than 100 inches.

Dr. Chao Wang, an assistant professor of chemistry at the University of California, Riverside, states that when designing the material, its high stretchability was expected because the team intentionally incorporated energy-dissipation sites into the polymers. Wang is co-author of an article published in the journal Nature Chemistry.

Muscle-like twitch

The material is made of a network of elastic polymers — a stretchable plastic-like substance — crosslinked together. The researchers also jolted the material with an electrical field and found that it responds with a muscle-like twitch or pulse. The material can self-repair any gaps or punctures at temperatures as low as -20 degrees Celsius since it bonds to itself.

The polymers become linked together like a big net through the metal ions and the ligands, says Dr. Zhenan Bao, professor of chemical engineering at Stanford University and lead author of the study.
Each metal ion binds to at least two ligands, so if one ligand breaks away on one side, the metal ion may still be connected to a ligand on the other side. “When the stress is released, the ion can readily reconnect with another ligand if it is close enough.”

Ideal for use in prosthetics

The researchers concluded that properties such as high stretchability and self-healing capabilities make the material ideal for use in the development of prosthetics — possibly even giving a prosthetic the ability to perform humanlike movements or to be controlled by a wearer’s own brain. Wang: “In the future, the material could possibly be linked to the neurons and driven by human neuron signals.”