Modelling And Control Of Dielectrophoresis- Based Micromanipulation Systems

In recent years,miniaturization has been an important trend in the development of natural science and engineering technology.Micro-nanoparticle manipulation technology is one of the key technologies of miniaturization.Dielectrophoresis is an ideal tool for micromanipulation and has a very broad application prospect.Because dielectrophoresis-based manipulation offers advantages such as noninvasive to the manipulated particles,controllable,low cost,and the device is easy to manufacture and easy to integrate into "chip labs.".Many biomedical and nano engineering studies and application require flexible and precise control of micro-object's position and orientation.While most current dielectrophoresis-based micromanipulation devices are incapable of meeting the demands.Aiming at enhancing the flexibility and accuracy of dielectrophoresis-based micromanipulators,this paper introduces control technology into the dielectrophoresis-based micromanipulation system through control the applied electrode voltages in real-time,thereby changing the uncontrolled open loop working mode of current devices.In this way,precise,real-time adjustment and control of the position and orientation of the manipulated particles can be achieved.The main contents of this paper mainly include the following aspects:(1)A new hybrid modeling method is proposed to establish two-dimensional approximation analytical spatial electric field models under arbitrary applied electrode voltages.The proposed method combines theoretical analysis using charge density method,numerical simulation,model identification and electrostatic derivation in its modelling procedure.Based on phasor notation of harmonic signals,the proposed method is applicable to modelling of electric fields that not only spatially varying in magnitude,but also spatially varying in phase.Quadrople and hexapole electrodes are used as modelling examples to illustrate the proposed method.Existing theoretical models and finite element simulations conducted by COMSOL Multiphysics software prove its effectiveness.(2)Based on the established electric field model,analytical expressions of the force and torque experienced by the particles are obtained through electrostatic mechanism analysis and derivation.,and the spherical and long ellipsoidal particles as the control object,through the mechanical analysis The dynamic model of the whole system of the system is established.The established models characterize the input nonlinearity and state nonlinearity of the systems.With the system model established,control design can be feasible then.In addition,manipulation systems with quadrupole polynomial electrodes and hexapole polynomial electrodes are designed for spherical and long ellipsoidal microparticles respectively.(3)For the purpose of flexible,precise and robust dielectrophoresis-based microparticle position control,several control designs are proposed.Dynamic model reference control is firstly used to illustrate that the dynamic strategy is able to effectively cope with the input nonlinearity problem of the system,and its trajectory tracking performance is verified through Matlab simulation.Then dynamic sliding mode control is designed to deal with position control in the presense of uncertainty and disturbance with known upper bound,Lyapunov theorem is used to prove the stability of the system.The effectiveness of the control design is demonstrated by simulation.Then,to achieve accurate trajectory tracking in the presence of uncertainty and disturbance with unknown upper bound,the adaptive law is introduced to merge with dynamic sliding mode control.The effectiveness of the adaptive dynamic control is verified by simulations.(4)Considering the demande of position and orientation control of microparticles in applications,uncertainty and disturbance estimator based dynamic sliding mode control is developed for the decoupled micromanipulation systems,and its stability is demonstrated.Matlab simulation shows that under the same conditions,the uncertainty and disturbance estimator based dynamic sliding mode controller has better chattering mitigation effect,smaller tracking error and better robust performance than uncertainty and disturbace estimator-based model following controller,dynamic sliding mode control and adaptive dynamic sliding mode control.Then the proposed controller is used for sequential control of position and orientation control of a spherical microparticle to realize the translational motion trajectory tracking and orientation trajectory tracking.Simulation results show that the predetermined trajectory is accurately tracked in the presence of uncertainty and disturbance,and does not produce control chattering.The proosed control offered a robust control design for a kind of non-affine nonlinear system in the presence of uncertainty and disturbance,which includes dielectrophoresis-based micromanipulation systems.