Transportation of multiple biological cells through saturation-controlled optical tweezers in crowded microenvironments

Transportation of biological cells has attracted increased attention in bioscience and nanomedicine. Existing approaches to achieve automated multicell transportation are generally based on numerous overstrict conditions or assumptions, including static and clean environments, complex theoretical convergence conditions, omitting tool kinematics, and off-line calibrations. This paper presents a novel approach for the automated transportation of multiple cells by using robotically controlled holographic optical tweezers. First, a swarming controller is developed with easily satisfied convergence conditions. The offset between centers of the cell and optical tweezers is constrained by saturation control to maintain the cells in the optically trapping area. An artificial first-order kinematic model of the tweezers is considered in the controller design to reduce controller oscillation. Second, a solution to the collision avoidance of random-moving obstacles is developed to remove the assumption of static or clean environments. Finally, an automated method based on the drag force model and gradient descent optimization is presented to calibrate cell dynamics online. Experiments on yeast cells are performed to verify the effectiveness of the proposed approach.