Résumé
Optical tweezers have received significant attention in the past few decades and many techniques have been proposed to achieve assorted manipulation tasks on cells or micro-objects. While traditional techniques for optical tweezers utilize laser beams for direct trapping and manipulation of cells, several approaches have also been proposed to achieve grasping and manipulation of cells. Most grasping approaches, however, have failed to solve the existing difficulties in the grasping process of cells due to limited sensing capability and presence of Brownian perturbation in the micro world. In this paper, a novel human-assisted grasping technique for manipulation of biological cells is proposed to facilitate the grasping process of biological cells. In the proposed technique, several microbeads are first trapped and used as fingertips to perform a grasping task on a biological cell. Based on human observation, the positions of the laser beams that trap the microbeads are remotely and simultaneously controlled through a touchscreen, and thus generating a grasping formation of the trapped microbeads to grasp the cell. After the cell has been grasped, a simple region control technique is utilized for automated manipulation of the grasped cell. This paper offers a flexible, reliable and efficient approach for grasping and manipulation of biological cells, and thus extending the feasible applications of optical tweezers. The stability of the control system for manipulation of the grasped cell is investigated by using a Lyapunov approach, and the feasibility of the proposed human-assisted grasping and manipulation technique is demonstrated by experiment result.