Biological applications of fiber optic trap

We have already developed a single-laser beam optical fiber trapping system. A biological cell dispersed in water solution could be easily trapped by a single laser beam emerging from an optical fiber, and the optically trapped micro-object could be freely transferred in 2-D plain synchronized to the trapping fiber. In this paper, multibeam cell manipulation was successfully demonstrated. Experimental results were as follows. (i) Separation/coupling of an individual cell from the cell groups was easily achieved using plural optical fibers. (ii) Optical force acting on an elliptically shaped object was experimentally analyzed. From these results, it was found that the optical force acting on an elliptically shaped object tended to rotate the object about the center of mass G of the object. (iii) Biological cell laid at the bottom of the sample chamber could be levitated against gravity using plural optical fibers. Micro object was captured and held at equilibrium point, where the force of gravity, the total axial forces in the downward direction and the total transverse forces in the upward direction balanced. From these experimental investigations, we verified that transverse forces played an important role in levitating a microscopic object using plural optical fibers.