Fabrication Of Metal Proportion Controllable Janus Particles Based On Compound Droplets And Their Electrokinetic Property Investigation

As a new fluid control technique,droplet microfluidic technology can generate droplets at the micro/nano level,and the resulting droplets have various forms and functions.It has become a new way for biological,chemistry,medical,materials and other engineering field to develop new materials and devices,which applications,cover,single cell analysis,drug screening,personal care,etc.Janus particles as a bipolar particle have good amphiphilic,and Janus particles with different structure have a various functions and potential applications,including drug delivery,composite materials,MEMS devices and so on.Traditional methods of Janus particles synthesis are complex,which need many instruments and have low utilization ratio for the materials.Compared with the traditional methods,the droplet microfluidic system can fabricate Janus particles with varying metal ratios simply and quickly.The droplet-based microfluidic chip is a research platform,which aims to provide methods for the applications of various fields.Different kinds of glass capillary microfluidic chips are designed and prepared based on the droplet's structure and function.In this paper,we designed a glass capillary microfluidic chip with ?-type glass capillary for “one step” fabrication of the Janus droplet.The research on the fabrication of metal proportion controllable Janus particles based on this chip is as follows.According to the basic theory of two phase flow in microchannels and stress analysis during the droplet formation process,the relationship between droplet size and fluid velocity is deduced,and the simulation model of droplet generation based on co-flow method is established.The key factors influencing the size and frequency of droplet formation,such as fluid velocity and surface tension,are simulated and analyzed to provide support for the design of glass capillary microfluidic chip.Based on the theoretical analysis and simulation design,the “one step ”generation of Janus compound droplets experimental platform is designed.The influences of continuous phase and dispersed phase velocity to droplet size,size uniformity and generation frequency are analyzed.The relationship between the two dispersed-phase velocities with the metal proportion in Janus compound droplet is studied.The Janus compound droplets are synthesized with high efficient and the Janus compound droplets are used as structural inducers to form the metal proportion controllable Janus particles under UV light.The Janus particles' asymmetric polarization,negative dielectrophoresis(DEP)force,frequency response characteristics and rotating in a non-uniform electric field is analyzed according to the dielectrophoresis particles manipulation theory.And then,the movement of Janus particles in the non-uniform electric field is analyzed.