Oil Droplet Dielectrophoresis And Its Application On Biosensors

Dielectrophoresis technology is one kind of method to effectively manipulatemicro particles. It can be used for collecting dielectric particles and live cells,separating particles, assembling nanoparticles. It has a broad applications in thebiological engineering and medicine research.This dissertation mainly aims to apply the dielectrophoresis technology captureand collecting of the emulsion droplets. We choose three different oil(toluene,hexane, silicone oil). The different voltage value, frequency, conductivity of oilphase and water phase were varied for investigating the dielectrophoresis behaviorof the oil droplets using quadrupole electrode and interdigitated electrodes.Combining with the simulation results and the theory, we proposed the oil dropletdielectrophoresis force formula and the velocity formula of the dielectrophoresistraveling wave. The vesicle electric electrorotation experiment was carried out. Asimulation of sensing avidin was also done based on the rotation rate of biotinmodified veside.First of all, we did simulations based on the theories of electric double layerand Newton fluid, discussed the dielectrophoresis movement behavior of differenttypes of particles on the electrode and deduced their theoretical formula. ThroughComsol and Matlab software, we simulated the particle collecting experimentquadrupole in different electric field. Through the experimental observation, weconclude that the PS spheres and oil droplets on the star electrode and asymmetricinterdigitated electrode had both the positive and negative dielectrophoresisphenomenon depending on the frequency of the field. In low frequency range, theparticles sufferd mainly positive dielectrophoresis force and move to the edge of theelectrode; which in high frequency range, the particles were driven by negativedielectrophoresis force and moved to weak electric field area away from theelectrodes. Using electrode, the positive and negative dielectrophoresis of particlewere observed as well. In a specific range of voltage and frequency, we can alsoobserve the traveling wave dielectrophoresis movement of particles in AC electricfield.We observed the elecrorotation of vesicle in real-time when sinusoidal AC field was applied to auadrolet electrods. The rotation speed and its influencing factorswere discussed comprehensively. The best electrorotion experiment conditions weregiven. Finally, according to the results of electrorotation experiments, we simulatedthe rotation rate of biotin modified vesides biotin on the surface of lipid vesicle,using interaction of biotin and avidin, changing the presence of different avidinconcentration.The innovation of our study is that we carried out the systematic simulationanalysis and experimental observation for the oil droplets and vesicledielectrophoresis, which were rarely reported. Further, we proposed an innovativeidea using the change of angular velocity of vesicle electrorotation to test avidin insolution. Through the simulation and experimental analysis, we completed the mostworks, but there are still some improvements need to be done, such as the study ofother droplets, and the improvement of detection sensitivity of biosensor.