Robot-Assisted Optical Trapping and Manipulation of a Biological Cell with Stochastic Perturbations

Several control schemes have been proposed for optical tweezers, but most existing methods assume that the optical trapping is maintained throughout the manipulation, and Brownian motion is ignored for the simplification of stability analysis. However, the optical trapping is not effective when a biological cell is initially outside the optical trap, and even if the cell is initially trapped, it may escape from the optical trap due to random Brownian perturbations and kinetic energy gained during manipulation. This paper presents a new robotic control technique to address the trapping and manipulation problem of biological cell in presence of random Brownian perturbations. By using the proposed method, the cell can be automatically trapped when it is not inside the optical trap and the optical manipulation of cell is enhanced by saturating the position feedback. The stability of the closed-loop system is analysed from stochastic perspectives. Experimental results are presented to illustrate the performance of the proposed control method.