South Korean scientists have developed tiny robots that don't need an engine or battery to power their movements. But it's not perpetual motion. Instead, the robots run on environmental humidity, absorbing the moisture in their surroundings to be powered by water.
In a new paper in , the scientists from Seoul National University describe the advantages of microrobots and how their so-called hygrobots could increase their usage. Microrobots can already help people have children and pull cars, but they're limited by the number of power sources available to them.
To solve the problem, the Korean team took an interdisciplinary approach. The paper's authors include Beomjune Shin of the SNU's department of mechanical and aerospace engineering as well as Gee Ho Park of the school's program looking at stem cell biology. The product is a bot inspired by plants.
"Most botanical movements are hydraulic in nature," the paper notes. The "simple transport of fluid (mostly water) in and out of the plant tissue generates motions." A great example of how water can create movement can be seen in with a few droplets of H20.
But robots are more complex than straw wrappers. A robotic system needs to have some semblance of reliability and stability. That movement should be in the correct direction and should be accountable to some mathematical predictability.
Building a frame out of fabricated hygroscopic PEO (polyethylene oxide) nanofibers with different densities, the SNU team was able to build a hygrobot that moves "spontaneously in a ratcheted fashion on a moist surface at a speed high enough to enable practical applications." They were also able to get their inchworm-style bot running through a variety of humidity levels thanks to the right nanofiber mixtures.
As for those practical applications, the team thinks medical and military scenarios, where a lack of an electric heat signature could be a plus for a variety of reasons. They were also able to create a mathematical model of motion for the hygrobot, which will allow the team to "obtain optimal geometric design to maximize the locomotion speed."
In other words, the hygrobot is just going to keep getting better.