Biomedical engineering

Toward artificial muscles

When Sumitra Rajagopalan discovered the principle of the artificial muscle—a hydrogel capable of contracting with calcium and expanding with sodium—she actually shouted “ Eureka ”! “It was late at night,” she recalls. “The principle came to me in theoretical form as I was reading articles, and I rushed off to the laboratory the next day to check my hypothesis.”

It was only the beginning of a process that is far from complete, says the doctoral student in the Institute of Biomedical Engineering at Université de Montréal. But the idea was there. “You can imagine that we will someday make artificial structures capable of replacing muscles destroyed by disease or accident. Obviously, this will still be far from what exists in nature. For example, our artificial muscles react to electrical stimulations of 1 volt, a 100 times too strong a signal.”

In the body, the voluntary muscles are very special elastics that respond to commands from the nervous system. They react to minute doses of chemicals liberated by commands from the brain. If you want to produce one of these elastics in the laboratory, you have to find the right material and the right communication system. Ms. Rajagopalan’s work has led to identifying a gel that is very similar to the muscle itself. Great progress has been made in the past few years in terms of intramuscular information involved in muscle contraction.

We’re not at the point where artificial muscles will be sold at the corner drugstore tomorrow. What is missing is knowledge of how this artificial body-part can be relaxed. But progress is being made: “It is a very exciting field, because we’re at the crossroads between biomechanics, chemistry and biomedical sciences,” she exclaims. In fact, robotics experts have now begun to show interest in her work. Artificial muscles for “intelligent” robots? We’re getting close to the famous cyborg.

Of Indian origin, but born in Hong Kong , where her father held a diplomatic posting, Sumitra Rajagopalan has had an interesting life that took her through several countries in Europe and Asia before she landed in Canada . It was actually at Saint Petersburg State University that she became interested in intelligent materials. The light-bulb switched on in a course on macromolecular chemistry given by Prof. Alexandre Bilibin. Noting the student’s enthusiasm, the Professor recommended her to one of his colleagues at the Pavlov Institute. She moved to the Institute, where she dove into the even more exciting world of programmable polymers. She was fascinated by the fact that it was within these very walls that the legendary Ivan Pavlov had conducted his research on conditioned reflex in dogs in 1903. Her thesis work on bioreceptors opened the way to the master’s degree she completed in the Department of Chemistry at Université de Montréal under the direction of Julian Zhu. This researcher, who works on thermosensitive polymers, enabled her to develop a promising material.