Excerpt from "These micro-robots do the breaststroke," from Rice University News & Media (via NSF.gov), posted on March 19, 2018.
Rice University scientists have discovered what may be the simplest form of locomotion in the travels of micron-scale particles linked and driven by a magnetic field.
In the Rice lab of chemical and biomolecular engineer Sibani Lisa Biswal, researchers placed magnetized spheres of different sizes into a solution. When subjected to an “eccentric magnetic field,” the spheres self-assembled and the smaller spheres, attached by virtual hinges, traced rough orbits to one side of their larger partners.
In essence, the small beads replicated the motion of a one-armed swimmer doing the breaststroke. The researchers found they could manipulate the magnetic field to direct swimmers through the fluid at nearly a micron a minute. The ability may eventually make them suitable as drug-delivery vehicles.
The phenomenon is the subject of a paper in the Royal Society of Chemistry journal Soft Matter.
“There’s been a great deal of recent interest in active matter and systems that show collective behavior,” Biswal said. “We’re used to seeing this in how birds flock or bacteria swarm, but now we can see it in synthetic materials that also show an ability to couple with each other.
“Magnetic fields have emerged as a way to be able to drive particles to do some interesting things,” she said.
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