Tiny robots powered by light have been developed that can hunt down and collect bacteria, according to research published in Science Advances. These nanorobots are approximately 50 times smaller than the diameter of a human hair, bringing researchers closer to the goal of interacting directly with the microscopic world.
The development of these microdrones is based on using the recoil produced by individual photons to move microscopic devices. The robots contain as many as four plasmonic nanoantennas that absorb light and emit it in a specific direction, creating a tiny recoil force similar to the recoil produced when a bullet is fired. This allows the microdrones to generate substantial acceleration and speed despite their small mass.
The researchers have further reduced the size of these light-powered robots, producing devices smaller than one micrometer while retaining propulsion based on photon recoil. The new control method takes advantage of nanoscale antenna wires built into the robot, which naturally tend to align with the polarization direction of incoming light. By changing the light’s polarization, the researchers can control which direction the nanorobot faces, creating a steering system that works somewhat like the directional control used in larger vehicles.
These robots are highly maneuverable and can make extremely fast 90-degree turns, helping them scan broad areas of a sample in an organized and efficient way. They can also selectively capture, carry, and release substantial numbers of bacteria under controlled laboratory conditions. This means the nanorobots can effectively “clean” microscopic environments by gathering bacteria from one area and depositing them at specifically chosen locations.
The robots remain fully maneuverable even while carrying larger groups of bacteria, although their speed decreases somewhat under the added load. The ability to keep functioning while transporting larger bacterial clusters points to possible future uses in microbiology, biomedical research, and precise manipulation of materials at the microscopic scale.