A Virtual-Assisted Controller for Biological Cell Transportation in a Dynamic Environment with Variable Field of View

Existing control methods for cell transportation with optical tweezers are generally implemented under the following assumptions: The obstacles are known in advance; and that the field of view (FOV) of the microscope is fixed during the transportation process. The unknown obstacles suspended outside FOV may float closely to the targeted cell, thereby always leading to failure of existing transportation methods. Fixed FOV also restricts the available manipulation space, thereby limiting the transportation within a small area. In this article, a novel control method that abandons the mentioned impractical assumptions is designed. The approach integrates the functions of cell transportation, cell maintenance, and obstacle avoidance. A series of virtual-assisted geometrical models, including 'virtual obstacles,' 'protecting ring,' and 'time varying reference region' are proposed to avoid unknown dynamic obstacles. Simulations and experiments on long-distance cell transportation with variable FOV, in accordance with the actual situation, are successfully performed. Therefore, the effectiveness of the proposed control method is demonstrated.