Imagine a robot that is able to move without any traditional power source. No electricity, no combustion, no wind, and no stored kinetic energy. That sounds far-fetched, but a team of researchers at South Korea’s Seoul National University have achieved that with their miniature Hygrobots.
The Hygrobots are able to move by repeatedly absorbing and then evaporating moisture. The bots have two types of nano-fibers on their body: one type easily absorbs moisture, while the other doesn’t. That causes contraction, like a muscle, which then relaxes when the moisture evaporates.
When that’s repeated multiple times, the Hygrobots are able to inch along like worms. The big challenge here is to create an environment that alternates between being humid and dry. One way to achieve that is with careful, but slow, climate control. But, the better way the researchers found was to put the Hygrobots on a wet surface in a very dry environment, which naturally creates a humidity differential perfect for their locomotion.