| Microparticle manipulation research is of great significance in the fields of biochemical analysis,chemical synthesis,medical diagnosis,environmental monitoring,and drug development.Among them,acoustic manipulation and dielectrophoresis（DEP）manipulation are favored by researchers for their advantages of label-free,low sample consumption and high efficiency.However,the high-frequency interdigital transducers mostly used for acoustic manipulation result in a complex and costly microfluidic structure,while the microelectrode structure and shape in the DEP manipulation lead to low channel flow,which cannot meet the demand of high efficiency,low cost and high throughput.In order to solve the current problems of high processing cost of acoustofluidic chips and low throughput and time-consuming processing of DEP microfluidic chips.In this paper,we propose a method based on low-frequency acoustic transducer to manipulate particles and cells.This method not only successfully manipulates the motion of PS microspheres and red blood cells,but also solves the high cost problem of using high-frequency interdigital transducers.In addition,a W-electrode DEP microfluidic manipulation platform with simple structure and high sorting efficiency was designed and fabricated,which was used to achieve the separation of eutectic gallium indium（EGa In）particles from red blood cells.The details include the following:Ⅰ.Preparation and performance analysis of EGa In particles.To address the problems of high cost,complexity of synthesis process and difficulty of surface functionalization in the fabrication of EGa In particles.In this study,EGa In particles in the range of 1-50μm were prepared using 200,300,350 and 420 mesh screens,and the effects of pressure of squeegee and screen mesh on the size distribution of EGa In particles were investigated,low cost,controlled size range liquid metal particle preparation was achieved.Ⅱ.Experimental study of acoustic wave manipulation of PS microspheres and RBCs.In response to the drawbacks of high-frequency transducer structure and high processing cost in acoustofluidic chips,In this study,we developed developed an open microfluidic platform capable of manipulating particle motion by using a combination of liquid crystal and acoustic wave driving method.When the transducer driving voltage is 13 Vpp,the frequency is 7.2k Hz,and the liquid crystal driving voltage is 30 V,the speed of PS in the liquid crystal flow field reaches 54.821μm/s.The experimental platform achieves the movement of PS particles in the high-viscosity 5CB liquid crystal according to a predetermined trajectory,as well as the movement of red blood cell enrichment.Ⅲ.Numerical analysis and experimental study of DEP manipulation of EGa In particles and RBCs.For the shortcomings such as low throughput of dielectrophoretic electric field sorted particles,the separation of EGa In particles from RBCs was simulated by COMSOL software in this study.An orthogonal test of the influencing factors（flow rate,driving voltage,driving frequency,and solution conductivity）was designed using L16（44）,and the optimal driving conditions for the W-electrode microfluidic chip were derived as a flow rate of 30μm/min,a voltage of 10 Vpp,a frequency of 100 k Hz,and a conductivity of 7μS/cm,when the sorting efficiency could reach more than 90%.The platform not only realizes the sorting of EGa In particles and separates EGa In particles from RBCs,but also improves the sorting throughput of the platform to 30μl/min.In summary,this project successfully manipulated PS particles,red blood cells,and EGa In particles by applying an acoustic or electric field around a microfluidic chip to achieve the manipulation of particles and red blood cells.The microfluidic platform designed in this paper expands the application of microfluidic technology in the fields of biomedicine,chemical detection and drug synthesis. |
