Automated Transportation Of A Single Biological Cell In Living Zebrafish With Robot-aided Optical Tweezers System

In vivo biological studies,especially in living animals,are important to observe the overall effects on a living subject and demonstrate knowledge acquired through in vitro studies.Research on in vivo biological activities will be greatly improved by developing a unique engineering tool that allows trapping and manipulation of a single biological cell within living animals.In vivo single-cell transportation,as the basis of cell manipulation in vivo,can lead to a controllable experiment in terms of number and location and helps in observing the performance of a target cell in a particular in vivo environment.Optical tweezers(OTs)can be used to manually manipulate a single biological cell within living animals.However,manual operation suffers from significant limitations in handling biological particles under complex in vivo environments with various disturbances and uncertainties.This thesis proposes an automated cell transportation system that integrates robotics and OT technologies to automatically identify,capture,and transfer single cells in in vivo environments.This work is conducted based on the three following perspectives.First,an in vivo cell tracking system is developed to identify the position of a target cell and track the cell automatically.The system utilizes image processing techniques,such as background segmentation,threshold segmentation,and Hough transform,and thus can identify cell location in complex in vivo environments.The identified cell can be tracked based on site correlation of cell motility.This system can track the position of the target cell in real time.Second,a robotic OT manipulation control framework is developed to automatically transport single target cells in vivo.A P-type closed-loop control algorithm is developed using the feedback of the detected cell position to automatically transport a single cell in vivo.A disturbance compensation controller is also developed to minimize the influence of the drag force of blood flow.This control method exhibits advantages in adjusting the trajectory of the cell transport online,trajectory correction,minimizing the steady-state error,and eliminating overshoot and thus can be applied to dynamic in vivo environments.The proposed approach is validated through simulations and experiments of tracking single red blood cells in living zebrafish.Third,a disturbance compensation controller with collision avoidance capability is developed to handle the collision avoidance problem during in vivo cell transportation.Collision mainly contributes to failure of in vivo transportation.A collision-avoidance vector method is incorporated into the disturbance compensation controller to avoid obstacles during cell transportation.This method integrates obstacle detection and collision-avoidance determination into one single step,thereby reducing the online processing time while enhancing the efficiency in obstacle avoidance.Different collision avoidance strategies can be used by adjusting the operator to suit for different transportation environments.The effectiveness of the proposed controller is verified through simulations and experiments.In summary,the proposed robot-aided in vivo cell transportation control system is an effective tool for precise tracking control of single cells in vivo.This research will benefit target therapy applications,such as drug delivery,in vivo cell extraction,and exploration of cancer metastasis mechanism.