One of the major design challenges was to find a way to keep the bots, which move like a corkscrew, from getting entangled in the eyeball’s mesh of biological molecules. The solution involved adding a kind of non-stick coating. Oddly enough, the Planck team turned to the world of plants to solve that problem.
“For the coating we look to nature for inspiration,” said Zhiguang Wu, first author on the study, in a statement. “We applied a liquid layer found on the carnivorous pitcher plant, which has a slippery surface to catch insects.”
Wu said that the synthetic non-stick layer is similar to the Teflon coating of a frying pan.
“This slippery coating is crucial for the efficient propulsion of our robots inside the eye,” he said, “as it minimizes the adhesion between the biological protein network in the vitreous and the surface of our nanorobots.”
For movement, the eyebots rely on a standard system used by other kinds of medical nanobots: magnets. Each of the bots has propeller-shaped elements that are seeded with tiny metal particles. Those particles respond to an external magnetic field, controlled by the doctor, which ultimately guides the robot to the desired location in the eye.
To test the new technology, the Planck team carried out a series of experiments using dissected pig eyeballs. Using a small needle, the team injected tens of thousands of the bots into the eyeball’s vitreous humor. They then used the magnetic fields to rotate each bot’s individual nanopropeller, guiding the entire swarm to the retina.
The next step in the research is to load the nanobots with cargo and test out different kinds of drugs and medicines. The idea is to deploy a nanobot eyeball swarm — savor that phrase for a moment — to deliver treatments within the eye without the need for surgery or other invasive techniques.
“We want to be able to use our nanopropellers as tools in the minimally-invasive treatment of all kinds of diseases,” said co-author Tian Qiu, “where the problematic area is hard to reach and surrounded by dense tissue.”