Research On Dielectrophoresis Motion Control Mechanism Of Biological Cells And Cell Patterning Biochip

The technology of cell manipulation plays an important role in cell research.Dielectrophoresis, which has advantages of non-contact and easy to control, provides a non-invasive mechanisms for manipulation of biological cells research. Based on the technologiesof dielectrophoresis and microfluidic chip, the thesis analyzed dielectrophoresis motion controlmechanism of biological cells, presented a cell patterning chip, and realized cell patterningunder action of dielectrophoretic force. This study has certain theoretical significance andapplication value for research of cell high throughput detection and cells interaction. The mainresearch contents are as follows:First, the basic theory of dielectrophoresis and the control mechanism of celldielectrophoresis motion were analyzed. The dielectrophoretic force expression of particles inalternating electric field was deduced. The impact of the AC frequency, the solutionconductivityand permittivity on dielectrophoresiswas discussed, and then the dielectrophoreticresponse of multi-layered structure sphere was analyzed according to the characteristics of cellstructure. The forces acting on particles in the fluid was also analyzed. Those studies laidtheoretical foundation of cells dielectrophoretic manipulation.Second, the dielectrophoresis chip for cell patterning was designed based ondielectrophoresis. The chip has three layers, the top and bottom are electrode layer and themiddle layer is microchannel. The distribution of the potential, electric field strength anddielectrophoresis were simulated by finite element simulation software COMSOL Mutiphysics,and then the structural parameters of the chip were optimized and determined. The width ofelectrodes is20μm, the distance between each other is40μm, and the height between top andbottom electrodes is50μm.The dielectrophoresis chip for cell patterning was fabricated and packaged considering thecharacteristics of microfluidic chip. The fabrication processes of ITO electrode and PDMSchannel were presented. The method of packaging the chip was also described.Third, according to the special requirement of dielectrophoresis chip, the experimental system for dielectrophoresis was developed. Then the positive and negative dielectrophoresisexperiments of yeast cells were performed. The influence of the AC amplitude, frequency andsolution conductivity on yeast cells dielectrophoresis were also exhibited and discussed. Theexperimental results showed that dielectrophoresis response of yeast cells with the change offrequency was in keeping with double layer model. With the increase of the frequency ofelectric field, yeast cells have experienced three stages in turn: negative DEP, positive DEP andnegative DEP. Furthermore, the AC frequency for cell patterning experiment was determinedto be1MHz, the AC voltage was8Vp-p, and the conductivity of the solution was5μS/cm.Finally, under those parameters of dielectrophoretic manipulation, patterning experimentof yeast cells was performed on the dielectrophoresis chip. The yeast cells affected by positiveDEP force moved to the higher density region of electric field, i.e., crossing points of top andbottom electrodes. The feasibility of the chip for cell patterning was examined and verified.