Researchers at the Institute of Biophysics in Szeged, Hungary, have employed laser tweezers to bi-directionally rotate a microscopic rotor made of a polymerized resin. The team created a rotor approximately 5 µm in diameter by performing two-photon polymerization on a UV-light-curing optical adhesive. The rotor was designed to respond differently depending on the position of its axis in relation to the focus of laser tweezers consisting of an infrared diode laser focused by an objective lens with a high numerical aperture. When the rotor was in front of the tweezers' focus, it moved counterclockwise; when behind the focus, it moved clockwise.The researchers, who reported their work in the June 17 issue of Applied Physics Letters, believe that rotors such as these may be useful in a number of nanotechnology applications, particularly in the manipulation of biological molecules.