(by Giovanni Calcerano) A team of researchers from Seoul National University of South Korea has created small robots that can move by absorbing moisture from the surrounding environment, without using any other form of energy. These new devices, called by the hygrobot researchers and described in the journal Science Robotics, can crawl, wriggle back and forth and twist like a snake. And in the future they could be used for a wide variety of applications, including the supply of drugs to human tissues.
The inspiration for these little robots comes from the phenomenon of plant growth, ie the ability of plants to change shape and size by absorbing water from the ground or from the air. For example, pine cones close when they are wet and open when they are dry, to ensure that the seeds inside them can disperse as far as possible.
However, the hygrobots in question are not made with plant substances but with materials able to imitate their mechanisms. Inspired by the seed bristles of Pelargonium carnosum, a shrub from Africa, the researchers have superimposed two layers of nanofibers, one of which absorbs moisture and the other does not. When the robot is placed on a wet surface, the moisture-absorbing layer swells, "pulling" the structure upward and away from the surface. Once the layer dries, the robot comes back and the cycle repeats. Using the structure of hygroscopic nanofibers in the best possible way, the research team was able to construct a device that, as we read in the research, moves "spontaneously in a continuous way on a humid surface at a speed high enough to allow applications. "practices. The team was also able to operate the robot in different conditions and at different levels of humidity, thanks to the choice of the right nanofiber mixtures.
To prove possible practical applications, the researchers showed that an antibiotic soaked hygrobot is able to cross a culture plate full of bacteria leaving behind a sterilized trail, much like the trail that a snail leaves on its way. . A hygrobot could therefore be used to "clean" a specific target tissue from bacteria that could hardly be reached by the usual systemic or topical therapies currently used.
It is also important to note that a robot that works only thanks to humidity is to be considered particularly precious because humidity is a natural source of energy and is not toxic, unlike batteries which can explode or release substances harmful to the body. human.
As for further applications, the team also thinks of military scenarios in which the lack of a "heat trail" could represent an advantage on more than one occasion. In addition, the hygrobots could also be equipped with sensors that respond to other gases and not just to water vapor, thus enabling them to operate in different scenarios.