Miniaturization has long been a high priority in the tech industry and traditionally the biggest challenge to overcome was simply manufacturing at small scales. But in many fields, we’re reaching a point where new challenges are arising. For example, we’ve nearly reached the absolute smallest possible transistor size in processors. Similar challenges await us in the field of robotics, as physics work a lot differently at tiny scales. Nano-scale robots don’t just need microscopic motors; they also have to overcome forces like surface tension. That’s why a team of researchers from Belgium and France are killing two birds with one stone with their Thermobots, which are able to walk on water thanks to manipulation by lasers.
There are many kinds of insects, such as mosquitoes, that can easily stand on water. They’re able to do that because they’re small and light enough that they can remain on top of the water without breaking the surface tension. They aren’t floating in the same sense as a boat, because they aren’t relying on displacement. They just aren’t exerting enough force to overcome water’s tendency to stick to itself. It’s easy enough for us to create objects that can achieve the same results, but giving them the ability to move around is a different question. Even our smallest motors are too heavy for a robot to stand on water, and that’s before even considering batteries, controllers, and so on. The solution that these researchers settled on was to use lasers to manipulate their Thermobots.
I’m hesitant to call these Thermobots “robots” at all, because they’re really just static pieces of plastic. The plastic bodies have “feet” so that they can stand on water, but they don’t have a single moving part or electronic component. Instead, external lasers heat up the water in specific spots. The infrared lasers collide with the water and create tiny currents. Those currents are enough to push the Thermobots away. By controlling the exact locations of the infrared lasers, the researchers can direct the currents to guide the Thermobots along set paths. An overhead camera watches the robot and ensures that the lasers strike the water in the correct points to push the robot where it needs to go. The Thermobots that they demonstrated measure 10mm across and at this scale the technology isn’t very useful. But similar techniques could be used in the future to manipulate nanobots that are too small to have any onboard means of propulsion.