Research On Cell Detection, Classification And Sorting Using Microfluidic Technology

Cell is the basic unit of all living structures and functions. In addition to the virus, it isthe smallest unit with full vitality of life. Cell detection, classification and sortingtechniques are important tools for biomedical research and clinical diagnostics. It has beenwidely used in various medical research fields, such as hematology, immunology, oncology,pharmacology and molecular biology. In recent years, the development of Point-of-caretesting technology makes miniaturized equipment with simple, accurate and timely featuresmore and more popular. Using this technology, patients can be examined with accuratediagnostic information on site by medical staff, which will help the diagnosis, monitoringand treatment of disease. Microfluidic chip has a series of features such as small size, highefficiency, high integration, fast analysis speed, low price. Microfluidic chip brings apromise to miniaturize cell detection, classification and sorting equipment, and has broadapplication prospects in human daily life. Therefore, using microfluidic technology for celldetection, classification and sorting, takes great significance and value, and has become oneof the hottest research topics in related field.The purpose of this dissertation is to explore cell inertia focusing, cell optical signaldetection techniques and cell electrical impedance detection technology, especially studydeeply on cell distribution in the microfluidic channel, label free cell classification usingmembrane elasticity and microfluidic cell electrical impedance detection method. The maincontents and contributions are as follows:1. Developed microfluidic chip based cell optical signal coding techniques. By meanof integrated spatial pattern inside microfluidic channels for cells scattered light encodingand signal processing method, small and low cost photodiode can be allowed in system toreplace bulky and expensive photomultiplier tube for large angle scattered light detection.Meanwhile, we can get three-dimensional distribution of cells in the microfluidic channelby combining encoding information and sysmetric flow velocity distribution in straightmicrofluidic channel.2. Developed a method to quantitatively assess the three-dimensional focusing designeffectiveness by using optical signal coding technology. Without the use of complexhigh-power microscope or visualization devices, the method can evaluate cell focusingperformance by particles flow velocity within the microfluidic channel.3. Proposed label free leukocyte classification using cell membranes elasticity and size difference of neutrophils compared to other types of white blood cells. In this paper, wehave performed the test using small amount of human blood. In a greatly simplified bloodpreparation process, skipping the usual steps of anticoagulation, centrifuge, anti-bodylabeling or staining, filtering, etc. We have demonstrated that our device and detectionprinciple can count neutrophils in whole human blood and is very suitable for Point-of-caredevice applying for cancer treatment.4. Aiming at the disadvantage of current microfluidic chip based cell electricalimpedance detection method, we have presented a microfluidics cell impedance detectionchip design in feature of relatively simple fabrication, suitable for mass production process.Instead of electroplated or deposited metal electrodes, off-the-shelf gold pins were used aselectrodes to simplify fabrication process, reduce cost, enhance device durability, and aboveall, achieve superior uniformity in E-field distribution for improved signal quality.5. Proposed cell classification method based on impedance ratio and demonstratedpreliminary result using white blood cells. Meanwhile，we have extended microfluidics cellimpedance detection application to cell sorting field. By detecting cell impedance signalfrom downstream channel, we can monitor cell sorting, optimize sorting parameters andvalidate sorting efficiency during the whole process.