Research On High-throughput Label-free Inertial Microfluidic Cell Separation Technology

Cell separation has always been the key technology of sample preparation in biomedical research.Both cancer diagnosis and single cell analysis need to isolate target cells from large cell background.The target samples are for subsequent downstream detection and analysis,so as to realize the diagnosis of the disease.Compared with the traditional large-volume cell sorting technology applied in clinic at this stage,the cell separation technology based on microfluidic can accurately manipulate the displacement of liquid or cells on the micro scale.Due to the small size of equipment,low cost and less sample consumption,it has great potential and high operation accuracy in the application of point of care testing(POCT).Among various microfluidic cell separation technologies,inertial microfluidic technology has attracted extensive attention because of its simple structure and high throughput.In order to explore the research of high-throughput label-free cell separation technology based on inertial microfluidic,four different single-stage inertial chips are studied and designed,and a multi-stage inertial microfluidic chip with high-throughput label-free cell separation and focusing is designed on the basis of the single-stage chip.In this thesis,rectangular section single spiral channel,rectangular section double spiral channel and trapezoidal section single spiral channel with the same section width of 400?m are designed,and three symmetrical rectangular serpentine channel with different section widths(200?m,150?m,100?m)are designed.Through preparation and experimental exploration of these channels,the general modes of focusing and separation of large and small particles in rectangular section spiral channel,trapezoidal section spiral channel and symmetrical rectangular serpentine channel are obtained respectively.Based on the single-stage chip designed and explored,a multistage inertial separation and focusing chip relying only on inertial microfluidic is designed and developed.The multi-stage chip integrates three-stage channels.The first stage is a spiral channel with trapezoidal section,and its separation performance is better than that of rectangular section spiral channel;The second and third stages use symmetrical rectangular serpentine channels with different sectional widths for further separation,focusing and deceleration of samples.The multistage channel can achieve a separation purity of 98.10% and a separation efficiency of 99.36% at a flow rate of1.3m L/min for separation of 5?m and 15?m particles.At the same time,our device can separate many kinds of circulating tumor cells(SW480,A549,Caki-1)from the background of large cells.The separation efficiency is > 85%,the separation purity is >90%,and the enrichment factor is about 20.The designed multistage channel provides the possibility of direct connection for subsequent analysis and detection.The flow rate at the final outlet is only dozens of microliters,which can be integrated with some low flow rate detection methods.The whole work aims to provide a convenient and efficient sample processing and detection method for rapid medical diagnosis.