The Effect Of Physical Parameters Of The Liquid Crystal Material On The Micro-drive Performance

The micro-driving method based on the liquid crystal drainage effect is an important branch of microfluidic control.Liquid crystal driving by applying an external field is currently the main research direction.Whether it is electromagnetic or temperature field driving,the physical parameters of the liquid crystal material are important factors that determine the driving performance.Therefore,it is necessary to study the influence of physical parameters on the driving performance.In this paper,taking nematic phase thermally induced liquid crystal DFP-PBC as the main research object,the influence law of temperature on the viscosity,elasticity and dielectric constant of liquid crystal material DFP-PBC is obtained through physical parameter measurement experiments and a large number of electric and magnetic field driven experiments,The key physical parameters that affect the driving performance of the DFP-PBC material are obtained.The research content of this article is divided into the following three parts:?1?Measurement of the main physical parameters of the liquid crystal material DFP-PBC.Differential scanning calorimetry?DSC?is used to determine the melting point and cooling point of the material.Build a liquid crystal material physical parameter measurement system.Making sure that the DFP-PBC material is in the liquid crystal state,the liquid crystal parameter measurement system is used to obtain the liquid crystal's expansion constant K₁₁,bending constant K33,and static dielectric perpendicular to the optical axis at different temperatures.Important physical parameters such as constant?_?,static dielectric constant parallel to the optical axis direction?_?,dielectric constant anisotropy??,and rotational viscosity of liquid crystal?₁are obtained.The relationship between each parameter and temperature is analyzed.?2?Improvement of the experimental devices and methods for external field application.Firstly,a new power amplifier and a temperature control part were made in the electric field driving experimental device;secondly,a magnetic field controller,an arc extinguishing device,a new observation part,and a temperature control part were added in the magnetic field experimental device;finally,in the part of driving experiment content,angle experiment,temperature experiment and continuity experiment are added.?3?Experiment and analysis of liquid crystal material DFP-PBC electric and magnetic field micro-driving.First,using the modified electric field driving experimental system,the relationship between the micro-driving speed and temperature of the liquid crystal DFP-PBC,the amplitude of the driving square wave electric field and the duty ratio,and the twist angle of the liquid crystal cell were studied;secondly,the modified magnetic field driving experimental system was used The relationship between the movement speed of the liquid crystal DFP-PBC driven by a strong magnetic field and temperature,magnetic field strength,duty cycle and period,and the twist angle of the liquid crystal cell were studied.Finally,a comparative study was conducted with the driving effect of the liquid crystal 5CB material,and the influence of the physical parameters of the liquid crystal material on the driving effect was analyzed.The research results in this paper will help to choose the appropriate liquid crystal material as the medium for microfluidic driving,or lay a theoretical foundation for synthesizing new liquid crystal materials suitable for liquid crystal drainage microdriving,so as to obtain the best driving effect.