Module Design And Study Of Cells Separating System Based On 3D Printing

Developed from micro electro mechanical system,microfluidics integrates the operations of biochemical experiments such as sample reaction,preparation,separation and detection into a very small chip.It has the advantages of low reagent consumption,low detection cost,high sensitivity and high efficiency.In this research,a cell separating system based on 3D printing was innovatively develops.The system consists of three parts: one was the droplet generation module,which was used to quickly and stably provide uniformly mixed cells droplets.The second was the micropump module,which acted as the power source of the cells separating system,and pumped the cells solution generated by the droplet generation module into the cells separating chip precisely and uniformly.The third was the cells separating module,which separated different cells from cells flow pumped by the micropump module to achieve efficient separation of blood cells and circulating tumor cells(CTCs).The main contents and achievements are as follows:(1)The factors that affect the processing quality of the light-cured 3D printer were explored,and a set of processing parameters suitable for the microfluidic module in this paper were found.Specifically,the effects including the resolution of dynamic mask,light intensity,exposure time,single curing layer thickness and photosensitive resin material on the processing accuracy were investigated.By adjusting different parameters,the test pieces were processed,and the processing errors were measured and calculated.Finally,the high dynamic mask resolution was selected,and the single printing layer thickness was set to 10 μm,the exposure time was set to 1500 ms,and the photosensitive resin model was D1141.When the size range of microchannel was 100～400 μm,the errors in width direction and height direction of the microchannel were about 10 μm.(2)Completed the design and fabricate of the droplet generation module from the cells separating system.A cross-shaped droplet generation module was fabricated by 3D printing,and the effects of the continuous phase flow rate and dynamic viscosity in the droplet generation module on the effective diameter of the generated droplets were explored.The numerical simulation and experimental results showed that the effective diameter of the generated droplets decreases with the increase of the continuous phase flow rate and the dynamic viscosity,and the maximum droplet equivalent diameter was about 120 μm.The module can adjust the properties of the continuous phase to obtain droplets of ideal size,and provide droplets of uniform size and cells concentration for the micropump module.(3)Completed the design and manufacture of the micropump module from the cells separating system.A valveless piezoelectric micropump module was fabricated by 3D printing,and the effects of driving voltage amplitude and driving voltage frequency on the pumping efficiency of piezoelectric micropump were investigated.The numerical simulation and experimental results showed that the pumping efficiency increases with the increase of the driving voltage amplitude,first increases and then decreases with the increase of the voltage frequency.The maximum pumping efficiency was about 150 μL/min in the voltage range of 0-200 V.The module can precisely and stably pump the cells fluid obtained by the droplet generation module into the cells separating chip by adjusting the voltage characteristics.(4)Completed the design and manufacture of the cells separating module of the cells separating system.In this study,two cells separating chips with different cross-sectional dimensions were designed,which can be applied in different scenarios.Through numerical simulation and particle separating experiments,the optimal flow rate of cells separating for each chip was found.Numerical simulation and experimental results showed that the smallsection cells separating chip can separate 93.33% of blood cells and 87.96% of CTCs from the original mixed solution when the optimal flow rate was 400 μL/min.The concentration of blood cells obtained after separation was increased by about 3 times compared with that before separation,the ratio of CTCs to blood cells in the obtained CTCs solution was increased by10.76 times compared with that before separation,and the concentration of CTCs was increased by 2.65 times.The optimal flow rate of the large-section cells separating chip was 200 μL/min for cells fluid and 1000 μL/min for sheath fluid.In the separating experiment of blood cells and CTCs,the purity of the isolated CTCs was about 40.64%,and the proportion of cells was increased by about 327.7 times.The module is assembled with the droplet generation module and the module to build cells separating systems with different processing throughputs.