Study Of A PDMS Microfluidic Chip For Detecting The Cell's Resistance

With the rapid development of micro-fabrication technology, micro-fluidic chip obtained widely attention from academic and industrial fields because of its many advantages such as significant system coherence, cheap and low sample consumption. Thus, studies on biological cell based micro-fluidic chips have also been deepened. In addition, the PDMS which is an important production material of micro-fluidic chips shows a broad application prospect in biology and medicine with its advantages such as low price, easily production method, the characteristics of non-toxic and so on. This subject was based on National"863"Project"High-throughput Cell Electro-fusion Microsystem"and National Natural Science Foundation Project"Study of a high-throughput cell-electrofusion method". Because the volume of the post-fusion cell is bigger than the not one and the PDMS is non-toxic, PDMS was selected as the main material to produce the micro-fluidic chips. The Coulter principle was used to detecting the resistances of cell which could distinguish whether the cell is fusion or not.Although common-used cross-type micro-channel configuration was used as reference in this paper, the morphological instability in focusing flow was found by simulation. Therefore, several improvements had been done. For example, different perspectives, different proportional on length of sample channel and sheath channel are established and simulated on the configuration of focusing flow. The SPSS software was used for the regression analysis and model establishment of multiple environmental factors, which provide the basis of setting conditions that the channels'length of sample channel and sheath channel determined by the size of actual cells. The lengths of the channels were from one to three ceilometers and the angle of them was 45 degree.PCB was used to fabricate the positive and negative modules. Based on these two modules, three chips, i.e. PDMS-PDMS, PDMS-glass and PCB-PDMS were made. On the chip fabrication aspect, the proportion of prepolymer, curing agent, and the solidifying temperature were studied, and the different surface modifying and packaging methods were also discussed. Finally, scientific procedure on chip fabrication was established.About the experiments, the experimental and simulation results on the configuration of the focusing flow were compared and the result showed they had good coherence. Focus-flow queuing detection experiments were carried out by using standard particles (50μm) and MC-3T3-Z1 cells. The MC-3T3-Z1 cell and HEK-293 cell were used to detecting resistance. The results show that the change of electric resistance value was positively correlative with the size of cells.The microfluidic chips used in this paper have some advantages such as low price, simple fabricating procedure, and so on. The electric-resistance detection different cells can be implemented by controlling the channel configuration and external pressure. These chips can be used to distinguish different cells and provide the basis for following target-cell capturing.