Reversible motion (IMAGE) University of Warsaw, Faculty of Physics Caption The novel double catalytic self-propulsion mechanism for Janus particles from the Nature Communications paper. The particles are made of anatase (a mineral form of titanium dioxide) and have a (bright) hemisphere coated with gold, as seen in the inset electron microscope image in the upper left corner. The bright field microscopic images are frames from a movie, in which initially (a-d) the particle exhibits free Brownian motion. The lightning bolt marks the start of illumination. (e-h) The particle propels when UV light activates the first catalytic mechanism. In the schematic drawing in (e, i) the gold colour represents the coated hemisphere. (i-l) The change of lighting to green visible light induces motion in the opposite direction. Scale bar in (l) is 5 micrometres. (Source: UW Physics, M. Lisicki) Credit Source: UW Physics, M. Lisicki Usage Restrictions The image may only be used with the following caption: The novel double catalytic self-propulsion mechanism for Janus particles from the Nature Communications paper. The particles are made of anatase (a mineral form of titanium dioxide) and have a (bright) hemisphere coated with gold, as seen in the inset electron microscope image in the upper left corner. The bright field microscopic images are frames from a movie, in which initially (a-d) the particle exhibits free Brownian motion. The lightning bolt marks the start of illumination. (e-h) The particle propels when UV light activates the first catalytic mechanism. In the schematic drawing in (e, i) the gold colour represents the coated hemisphere. (i-l) The change of lighting to green visible light induces motion in the opposite direction. Scale bar in (l) is 5 micrometres. (Source: UW Physics, M. Lisicki) License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.