A team of scientists of the Julius Maximilian University of Würzburg (Germany) now plans to transfer these principles and features to the nanometre scale. Their intention is developing tiny nano drones that can be controlled via laser. The cloud: the polarised laser rays will not only carry control information but likewise the power for operation.
If successful, the scientists would have created an entirely new class of nano tools that can be steered with extreme precision through liquids – to the benefit of nantotechnologies and life sciences. For instance, these drones could assume tasks like performing 3D scans on nano particles, or arranging such particles in a given order. Another imaginable application would be manipulating objects within cells.
Physics professor Bert Hecht who leads the research team has an idea that illustrates the scientific dimension of the project: The nano drones will be made of monocrystalline gold. They will absorb laser light in multiple polarisation planes and forward their impulse to plasmonic waveguides. These waveguides are correspondingly shaped to generate a recoil through emitted photons. This recoil makes the drone travel through space.
But how can the drones be controlled, how can they change their direction? Hecht has an answer: “Interestingly, the stimulus of these waveguide modes becomes very asymmetric if one uses circular polarised light”, the scientist says. “This enables us to perform lateral movements or turns.” This property of light in the proximity of matter, discovered relatively recently, is called optical spin-trajectory coupling.
By applying pulse sequences with different polarisation it should be possible to “steer the flight path of nano drones through liquids as exactly as you can steer their large counterparts when delivering parcels”, said Hecht.
The project is funded in part by the Volkswagen foundation. The Experiment! Program of the carmaker fosters research projects that follow a rather radical approach in the areas of natural, engineering and life sciences.