Light-Driven Microdrones

Thanks to optical tweezers, minuscule objects like biological cells and their internal components can already be precisely studied and manipulated. Yet, even this remarkable tool has its limitations. For example, it is hard to change the orientation of a trapped object and thus to access it from several sides, or to make several small objects interact in a targeted manner. As for micromanipulators, these are e.g. limited by their angle of attack and the mechanical connection to the machinery driving them.

Each microdrone consists of a stiff sheet a few micrometers in diameter. On it are several nanoantennas that each absorb light of a specific wavelength and polarization and re-emit it in a defined direction, thereby pushing the drone itself in the opposite direction. Constructing each antenna to react to a different kind of light, they can thus be individually controlled, simply by varying the intensity of the light sources used to illuminate the drones. Akin to the individual control of the rotors of macroscopic quadcopter drones, this is used to move and rotate the microdrones in any direction.