In the latest issue of the prestigious scientific journal Nature Communications, researchers from the University of Würzburg showcased a breakthrough invention: nano-scale machines that act like “cleaning robots.” They are so small that their diameter is a mere 920 nanometers (less than a thousandth of a millimeter), and their mass is over a thousand times smaller than previous similar designs.
Laser-driven race cars in the microworld
How do you power a machine that can’t fit a battery? With light. The nanorobots are set in motion using a standard, unfocused laser beam. They utilize special “plasmonic antennas” that reflect photons in such a way that the machine is literally pushed forward. By altering the light’s polarization, scientists can precisely steer the robots, forcing them to turn and draw complex patterns (during tests, the machines flawlessly “drove” the letters “EP5,” for example).
What’s more, these nanorobots are incredibly fast. Under favorable conditions, they can speed along at up to 50 micrometers per second, a truly sprinter-like result at this scale.
A vacuum cleaner that catches staph
The real magic begins, however, when the nanorobots encounter bacteria on their path. Scientists tested them in suspensions containing real pathogens: E. coli and staphylococcus (Staphylococcus carnosus).
The gold elements of the robot, gently heated by the laser light, create a specific field around the machine (utilizing so-called thermophoretic forces). It acts like a microscopic vacuum cleaner that literally attracts and “glues” surrounding bacteria to the robot. Crucially, the temperature around the robot rises by less than 10 degrees Celsius, which is completely safe and does not damage living cells.
The machine can gather a whole cluster of bacteria around itself and tow a load hundreds of times heavier than its own weight. It can then transport them to a designated zone. The entire process is 100% reversible – simply turn off the laser, and the captured microbes instantly float away.
The medicine of the future?
As the researchers themselves note, the potential applications for this invention are massive. Imagine such robots programmed to pinpoint and trap toxins in the body, safely “sweep” dangerous pathogens from specific tissues, or perform highly precise targeted drug delivery directly to the site of an infection without putting strain on the rest of the body.