Transportation of cm-sized solid substrate by laser

We have found that a cm-sized object floating on water is transported by the irradiation of green laser (wavelength: 532 nm). The object which are made of aluminum move away from the forces point of the laser as the laser are irradiated to the object. Based on the experimental results, the difference of interface tension surrounding the object leads to the transportation of the object, which are generated by the gradient of temperature induced by the irradiation of laser. The maximum of driving force due to the irradiation of laser is 0.9 μN at least in the present work, which is 6 orders of magnitude larger than that for a technique of laser tweezer.