| Micro-nanometer particles can be fixed,separated,collected,captured and transported by the microfluidic technique based on dielectrophoresis(DEP).The technology has great potential in many aspects,such as biomedicine,instrument making industry,criminal cases investigation,purification of sewage.Due to the DEP force subjected by many factors,it is significant for particles controlled precisely and effectively by microfluidic technique to analyze and utilize parameters of DEP.Based on DEP force to manipulate micro-nanoparticles enrichmented,captured and assembled,this topic investigated the controllable DEP parameters and convection mechanism.And the research work was undertaken as the following aspects.Firstly,based on the DEP force driving spherical particles,the principle of DEP force of cylindrical particles was discussed,and the function of DEP force of two-dimensional particles was deduced.According to the finite element method,the model of making the micro/nano electronic material contact with electrodes was built.By coupling force-electricity-flow field,the process of assembling carbon nanotube and graphene by DEP force was stimulated.The influence of parameters of DEP force on assembling carbon nanotube and graphene was quantified and some results were got.In the near electrode area,the shape of the electrode significantly influences the efficiency of assembling two-dimensional graphene,and rectangular and circular electrode will be better than the triangle electrode,but the effects of electrode shape on one dimensional carbon nanotubes are smaller.Type of DEP is determined by frequency,and frequency of 10~5 Hz was considered to assemble carbon nanotubes and graphene between electrodes.The optimum range of?,which is the ratio of electrode spacing to the length of material,to assemble carbon nanotubes and graphene is0.5~1 and 0.4~0.6 respectively.Secondly,considering that the transmembrane voltage will affect the cell activity,it is suggested that negative DEP was utilized to stabilize the cell in the low electric field,and the impact of convection of AC electroosmosis(ACEO)was introduced.A model with four electrodes was intended to simulate the motion of cells in this microchannel structure.It was analyzed that the distribution of the original flow field will be disturbed by ACEO,which is contributed to Hela cells deviating from the target region.And by quantifying the Hela cells deviating from the target area,the results showed that Hela cells can be captured in the target area as follows:when the voltage is 2 V,the frequency is less than 420 Hz and more than 31000 Hz;when the voltage is 3 V,the frequency is less than 630 Hz and more than 10000 Hz;when the voltage is4 V,the frequency is less than 570 Hz and more than 16000 Hz;when the voltage is 5 V,the frequency was less than 630 Hz and more than 17000 Hz.Therefore,by controlling the voltage and frequency,the effects of ACEO can be avoided,ensuring that the DEP force drives Hela cells to move into the target area.Finally,particle enrichment experiments were prepared and tested based on DEP.Using polystyrene microspheres as the Hela cell model,a three-dimensional model was established to simulate the movement of polystyrene microspheres by positive/negative DEP force.With the simulation results as a guide,an experiment was carried out to enrich the polystyrene microspheres with interdigitated electrodes.Comprehensively,a range of voltages from 2 V to 3 V was given to enrich the polystyrene microspheres effectively... |
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