Research On Key Technologies Of Zebrafish Larva Micromanipulation System

Zebrafish is a typical species of vertebrate model animals due to its attributes that include high genetic similarity with human beings,ex vivo growth in aqueous medium,high physiological growth rate.In the past decades,Zebrafish has been proven to be an increasingly researched biological target,and has important scientific value in biological genetics,development,and drug toxicology,etc.However,research of Zebrafish larva's specific organ mechanism and healing potion requires to inject foreign materials(such as molecular compound,biological drug,etc.)precisely into the target site,which is usually operated by longtime-trained operators manually.Manual injection is laborious,time-consuming,and has a low experimental consistency,i.e.,different results may be obtained by operators with different experiences even if operating in a similar manner.Although micromanipulation systems towards life science(including microinjection,microimaging,microsurgery,etc.)have attracted a wide attention of scientific researchers,and microinjection systems with targets of cells or embryos have been commercialized,no mature micromanipulation scheme is developed for Zebrafish larvae that have their own consciousness and behavior,irregular contours,and complicated inner structures.This paper aims to solve key scientific problems in micromanipulation system for Zebrafish larva,and presents complete scheme and novel design.The main content of the paper includes:For the new concept of micromanipulation system of Zebrafish larva,combining specific requirements proposed by life science researchers,this paper presents implementation scheme and key technological indices.According to different experimental tasks,this paper designs two-dimensional and three-dimensional rotation control of Zebrafish larva,compliant capture technology,and three-dimensional localization of Zebrafish larva inner organs.Compared to traditional manual microinjection,the developed system achieves single injection with average time of 150 seconds,and the injection survival and success rate are not lower than those performed by operators.In addition,the system has a potential application in injecting other organs such as kidney,liver,etc.For the feedback problem in Zebrafish larva micromanipulation system,based on the traditional computer vision algorithms,according to the narrow field of view and depth of view of the microcopy imaging,this paper presents a series of computer vision algorithms,including wide-range automated locating end-effector tips,precise localization of holding pipette tip,three-dimensional localization of pipette tips,three-dimensional localization of Zebrafish larva inner organs,etc.Different from the traditional computer vision algorithms,the proposed algorithms focus on micropositioning strategy,that aims to solve the problems of fully or partly missing image feedback.For the posture control problem in Zebrafish larva micromanipulation system,this paper presents the control strategy utilizing micropipettes and rotational plate.The twodimensional rotation process is modelled as switched system,and the stabilization controller is designed with a class of general switching signals,mode-dependent dwell time with unstable subsystems.The designed controller adopts multiple combinations of PD controller parameters,which is capable of effectively lowering conservatism of traditional fixed-parameter PD controller.In addition,to realize the rolling motion of the larva,this paper develops a 4-DOF micromanipulator with an additional rolling axis,which enables the rolling control of the Zebrafish larva.For the problem of compliant capture control of the Zebrafish larva,this paper presents the switched model predictive control algorithm.The capture process varies with the inhaled length of the capture fish skin,mainly due to the fact that the inhaled blood and skin stiffness tends to persistently be inhaled if the inhaled part is too large.Thus,we modeled this process as a switched linear system,with constraints guaranteeing that fish cannot be inhaled too much to prevent damage,not too little to prevent drop out,and designed the nominal controller with admissible switching time constraints.In addition,we also give the method of computing feasible region of the switched system,and corresponding simplified-specialized version in applications.Finally,this paper gives the verification of the presented algorithms,and concrete implementation manners with considerable details in designing stabilization controllers with admissible switching rules.We also give full analysis of the system performance indices(such as stability,accuracy,efficiency of algorithms;success,survival rate of the system,etc.).