Real-time 3D force/position sensing system by a single CCD for optically driven micro-robot

Many researchers have measured cellular mechanical properties for uncovering cellular life phenomena. No method, however, has simultaneously realized both mechanical analysis of cells and high-speed tracking ability of cell-manipulator in three dimensional (3D) space. Hence, it is difficult to measure accurate cellular mechanical properties and understand cell life phenomena because cells are 3D structures. There are significant problems. To solve these problem, herein we developed a novel system which concurrently enables both real-time 6 dimension of freedom (6-D.O.F.) positioning of microrobots measuring cell and analysis of 3D mechanical properties with a single CCD fixed to micro-scope. This system was realized by installing three markers like circular truncated cone to the microrobots. By observing diameter of each marker from a single plane image, we got position and posture of the micro-robot. Then, cellular reactive force was calculated from displacement between 3D position of micro-robot and laser focus. Compare with conventional 3D imaging systems, this system had advantages in that it can image and mechanically analyze in 3D from a single plane image in real time. Accordingly, this unique system contributes to the micro mechanical analysis for cellular biology.