Influence Of Driving And Medium Parameters On Micro-driving Performance In Liquid Crystalline Microfluidic Driving

The Liquid crystal is a fourth-state substance with both fluid fluidity and crystal anisotropy.The Liquid crystalline materials will produce controllable microfluidic under the condition of external electric field,which makes it possible to be used as microfluidic driving medium.In order to explore the influence of external driving parameters and physical parameters of liquid crystalline materials on microfluidic,four kinds of liquid crystalline materials were selected,an experimental platform was built,and a large number of parameter measurement and microfluidic driving experiments were carried out.Based on the experimental data of parameters,the simulation software of liquid crystalline microfluidic was developed.The microfluidic of different liquid crystalline materials under different driving conditions was simulated,and the influence mechanism of driving and medium parameters on the microfluidic effect of liquid crystalline materials was studied.The main work of this paper includes:(1)The experiment of DSC for selecting the liquid crystalline materials suitable for microfluidic driving experiment.Firstly,the DSC experiment was carried out on the selected liquid crystalline materials to analyze the applicability of the liquid crystalline materials.Whether the image of the data obtained through the experiment has two obvious exothermic peaks,that is the solid state changes to the liquid crystalline state and it changes to the liquid crystalline state.The existence of two peaks showed that the liquid crystalline material has a relatively stable liquid crystalline state and could be used in subsequent experiments.(2)Liquid crystalline parameter measurement experiment for measuring the dielectric parameters of liquid crystalline materials in different temperature ranges,the selected liquid crystalline materials were tested.The physical parameters of each liquid crystalline material in the temperature range of liquid crystalline state were measured,including elastic parameters,dielectric parameters,viscosity parameters and threshold voltage.(3)Based on the physical parameters measured by experiments,a numerical simulation software was developed.In order to analyze the influence of driving and physical parameters,a simulation software was developed based on Non-Newtonian fluid continuity equation,Momentum equation,Leslie-Erickson constitutive equation,Frank free energy density equation and Angular motion equation.Based on the experimental data of parameter measurement,the viscosity parameters and torsional elastic parameters of Leslie material were calculated theoretically according to the related formulas of DOi and Marrucci-Greco.(4)In order to verify the influence of physical parameters on microfluidic driving effect,a liquid crystalline microfluidic driving experimental platform was built,and the micro-drive effect of liquid crystalline materials at different temperatures was tested,and the glass plate on the liquid crystalline box was continuously driven.In the experiment,the square wave electric field was used as the driving source electric field,and the intensity and frequency of the electric field(combined with the duty ratio)were used as the main research parameters of the external driving electric field.The results of the influence of different driving parameters on the microfluidic driving effect were obtained,and the influence of external field parameters on the microfluidic driving performance was analyzed.(5)Analysis of the influence of material physical parameters on microfluidic driving performance.On the basis of developing software calculation,the liquid crystalline microfluidic driving performance of four kinds of liquid crystalline materials was simulated by C++ language.The simulation data were compared with the actual driving experiment results,and the results were in good agreement.According to the simulation results,the influence of physical parameters of dielectric materials was analyzed,and the optimal driving dielectric material parameters were determined.We can know that the driving parameters of external field and the physical parameters of dielectric materials have great influence on the driving effect of liquid crystalline microfluidic from this paper.In order to obtain better driving performance,it is very necessary to choose a suitable driving external field with the best physical parameters of the medium.The conclusion of this paper will lay a theoretical foundation for the chemical synthesis of liquid crystalline microfluidic dielectric materials and the selection of external field.