Small robots that move without a motor, with the help of moisture in the air, were developed inspired by the movement mechanism of seeds
By: Or Amr
A group of researchers from Seoul National University has developed a group of small robots that are able to move without a motor or batteries. Instead, as the researchers explained in the journal 'Science Robots', the hygtobots move by absorbing and evaporating water.
There are certain seeds which can propel themselves into the ground; Pelargonium carnosum (Pelargonium carnosum) is an example of such a seed. The researchers examined how such seeds move without the need for a motor and found that their outer shell contains many layers - some absorb moisture from the air and the others do not. When the air is moist, the outer shell stretches and causes bending, resulting in movement.
The researchers then applied what they learned to small objects, through the use of nanofibers as an outer shell, with some fibers absorbing moisture and some not. These small objects are a form of hygrobots because they move based on moisture activity. In order to cause movement, each hygrobot is uniquely designed so that when it is relaxed, only one end of it moves and causes the entire robot to move in slow motion. The movement is in a certain direction, with the moisture causing the robot to bend and relax itself in a toothy way.
The movement of the hygrobots required control of the degree of humidity in the environment. In some cases, the team quickly cycled the air in which the robots were operated between dry and humid. But they also found that using the right combination of nanofibers and a dry environment allows them to produce a hygrobot that is able to move across a wet surface using only the natural moisture differences.
The team recorded on video some of their creations while in motion, including a robot in the shape of an inch worm that makes its way on a surface, and another robot, which in its movement resembles a sand snake, on another surface. Another video shows a smaller version of the worm-shaped robot moving in a petri dish and carrying an antibiotic that cuts bacteria stuck to each other on the surface. According to the group of researchers, the robots may one day be effective for various military uses, for medical treatments or as robots that are able to deliver drugs into the body.
