A new study published in the journal Nature Physics has shown that from three simple ingredients, tiny, self-powered floating robots can be made. Researchers have combined oil droplets with water containing a substance similar to a detergent and have found they can create artificial devices that can float on their own and even collect energy to recharge.
Oil droplets use fluctuations in ambient temperature to store energy and float. When cooled, the droplets release thin “tail” filaments into the environment. Friction between the tails and the surrounding fluid pushes the droplets into motion. When heated, the droplets retract their tails, returning to their original state, and use the heat of the environment to recharge.
Researchers have shown that the droplets are rechargeable multiple times and can float for up to 12 minutes at a time.
Scientists have noted that there are other types of artificial swimmers, but their movements are driven either by chemical reactions that form bubbles that push the devices through liquids, or by physical forces such as magnetic or electric fields. Instead, a new class of microscopic robots, roughly the size of a red blood cell, are able to spontaneously assemble and move without the use of external forces.
Since they do not harm other living things, scientists hope they can be used to study basic interactions between living organisms such as bacteria and algae.
“In nature, we often see a large number of organisms, such as bacteria, grouping together, but our understanding of how these organisms interact with each other is incomplete. By mixing simple artificial swimmers with groups of living organisms, we can get a clearer picture of how biological micro-swimmers communicate with each other, ”the scientists noted.