A simple setpoint controller for dynamic manipulation of biological cells using optical tweezers

Optical tweezers are one of the most common and useful tools in non-contact cell manipulation. While several control methods have been developed for cell manipulation using optical tweezers, the control input is commonly treated as the position of the laser beam and open-loop controllers are designed to move the laser source. Investigating the interaction between the robotic manipulator of laser source and biological cells can help us gain understanding into the dynamic manipulation problem using optical tweezers. However, the interaction between the cell dynamics and the manipulator dynamics leads to a fourth-order overall dynamics, and the use of high-order derivatives of the state variables is usually required in the overall control input. In this paper, a simple setpoint control method is proposed for optical manipulation of biological cells. The proposed method is able to manipulate the trapped cell to a desired position without using the high-order derivatives of the state variables such as acceleration and jerk. The stability of closed-loop system is analyzed by using LaSalle's invariance principle, with the consideration of the dynamics of both the cell and the robotic manipulator. The proposed control method is simple and easy to implement. Both simulation and experimental results are presented to illustrate the performance of the proposed control method.