At the 245th National Meeting & Exposition of the American Chemical Society, in New Orleans, scientists from the University of California, San Diego, described their advances in micromotor technology that, they say, could open the door to broad new medical uses.

Joseph Wang, DSc, who led research on the motors, said that some micromotors and nanomotors have relied on hydrogen peroxide fuel, which could damage body cells. Others have needed complex magnetic or electronic gear to guide their movement.

But, he says, “We have developed the first self-propelled micromotors and microrockets that use the surrounding natural environment as a source of fuel. The stomach, for instance, has a strongly acid environment that helps digest food. Some of our microrockets use that acid as fuel, producing bubbles of hydrogen gas for thrust and propulsion. The use of biocompatible fuels is attractive for avoiding damage to healthy tissue in the body. We envision that these machines could someday perform microsurgery, clean clogged arteries, or transport drugs to the right place in the body.”

Wei Gao, a graduate student in Wang’s lab, described how the research team has developed two types of self-propelled vehicles—microrockets made of zinc, and micromotors made of aluminum. The tubular zinc micromotor is one of the world’s fastest, able to move 100 times its 0.0004-inch length in just one second. The zinc lining is biocompatible, reacting with hydrochloric acid in the stomach, and releasing the hydrogen gas as a stream of bubbles, which propel the motor forward.

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