Research Of Automatic Cellular Measurement And Separation System Based On The Mechanical Properties Of Cells

As the basic units of life, the researches into the structures and functions of cells areof great biological significance. With the vigorous development of cell biologicalstudies, people demands for higher performance of the cell separation and purificationmethods. Although a large number of cell separation and purification methods havebeen developed, the cells have to be marked using labeled biomarkers such asfluorescein or magnetic beads, which will absolutely change the characteristics of cellsand cause problems into later scientific experiments after the process of cell separationand purification. As a result, the cell separation and purification method based onlabel-free biomarkers becomes a new research spot.As a newly discovered label-free biomarker, the mechanical properties of cellsreceived more and more attention. However, the current methods of mapping thecellular mechanical properties are mostly carried out manually and this results in thatthe measurements are time consuming, which cannot meet the demand of testing a largequantity of cell samples for biological statistical analysis. Meanwhile, the current cellseparation and purification methods cannot be used in the label-free biomarker field,hindering the cellular mechanical properties’ application in the cell biology as thelabel-free biomarker. To solve these problems, an automatic cellular measurement andseparation system based on the mechanical properties of cells known as a label-freebiomarker is proposed in this dissertation. AFM is used to characterize the mechanicalproperties of cells rapidly, and cells are then separated automatically based on thecellular mechanical properties to improve the efficiency of cell separation withoutbringing any harm to cells. To achieve these goals, the major studies of this dissertationinclude:(1) The lack of effective abilities to locate the probe around the cell centers rapidlyand accurately is the main roadblock during AFM measurement. To solve this problem,the technique which combines the visual image processing method and tip positioningmethod based on local scan is proposed to locate the AFM tip and the cell centersrapidly and precisely, thus improving the efficiency of AFM based cellular mechanicalproperties measurement.(2) To separate cells accordingly, we still need to pick and place cells from onepetri dish to another after AFM measurement. So the cell picking method based on capillary micropipette is discussed in this paper. It mainly includes setting up the fluidcontrol system, analyzing the advantage and disadvantage of different cell pickingmethods, based on which one fluid control strategy based on voltage feedback is givento realize the automation of cell picking.(3) Finally, the newly developed technologies are implemented on an automaticcellular measurement and separation system based on the mechanical properties of cells.It mainly includes the rapid tip positioning method, stable cell picking method withoutharming the cells and the software and hardware design of the automatic system.Experiments have been carried out with the newly developed system to validate theeffectiveness of the proposed method.In summary, the work of this dissertation is not only of importance significance topromote the application of the cellular mechanical properties as a label-free biomarker,but also providing instructional theoretical methods and research approaches for thedevelopment of the automatic nanomanufacturing and cellular molecular biology.