Research Of Integrated Cell Processing Microfluidic Chips Basing On Dynamic Temperature Mass Transmembrane Properties

The development of cryo-biology has achieved significant results in the long-term preservation of various biological samples.However,the current cryopreservation procedures commonly used are often in the same way.Lack of cell specific process will cause non-optimal cryopreservation survival rate,which may cause waste and loss of samples,especially for some precious bio-samples.In addition,repeated manual operations in traditional cryopreservation research would easily cause measurement errors and sample contamination.All of these are inconformity to the trend of future technology in precision,miniaturization,integration and automation.Therefore,using microfluidic technology to study the properties of cell membranes and cryopreservation,as well as designing and manufacturing microfluidic chips for the integration of cryopreservation processes in this study is meaningful.In this study,a microfluidic chip with a “stair” microstructure was used to capture and observe the osmotic reaction of Jurkat cells(leukemia)in the permeable protective agent and the non-permeable protective agent at two temperatures.Then,image processing technology and the mathematical model of mass transfer across cell membranes were used to fit and obtain the permeabilities of Jurkat cells to water and dimethyl sulfoxide.A transmembrane mass transfer model under dynamic temperature for Jurkat cell was built.Based on the numeric model,a microfluidic chip with micro gold temperature-controlled electrodes,which can be used to study the relationship between the properties of cell membranes and temperature changes,was designed and manufactured by "Lift-off" technique.Aiming at cooling and rewarming process during cryopreservation,this paper combines photolithography,wet etching and soft etching technology to design and manufacture a high-transparency multi-layer microfluidic chip based on ITO glass and PDMS materials.The heating performance and heating range of the on-chip micro-heater were tested and studied.The heating performance and heating range of the on-chip micro heater were tested and studied,and the micro temperature sensor was calibrated and tested at 0 to 80°C.Furthermore,the proportional control method with Bang-Bang algorithm was used to realize a temperature control system based on the Arduino control board.Additionally,based on the temperature distribution recorded by the thermal imager and the temperature distribution in the flow channel obtained by multi-physics simulation,a variety of designs and layouts of micro heaters were compared and analyzed.Finally,the theoretical analysis,simulation analysis and experimental verification and analysis of the cooling effect of the on-chip cooling channel above and below room temperature were carried out,and natural cooling was also compared with.For the gradual concentration addition of protective agent during cryopreservation,the removal of protective agent after rewarming and the resuspension of samples after centrifuging,this paper designed and manufactured a small sample cryopreservation microfluidic chip that can achieved integrated protective agent gradient generation,active mixing control for biological sample addition,sample centrifugal enrichment,protective agent removal,sample resuspension and sample collection.In the research,different chip materials were compared and selected.The gradient concentration generation method was theoretically studied and experimentally compared.The structure design,dynamic characteristics,control methods and mixing effects of the on-chip mixing microcavity driven by the micro air pump were carried out.And then,the design and test of the method of sample centrifugation,enrichment and protective agent removal in the chip were completed.Moreover,the resuspension process of sample pellet assisted by the on-chip microchamber was tested.The microfluidic chip in this paper can realize the functions in the cryopreservation process such as temperature control and concentration control on the chip,and provide theoretical and experimental guidance traditional cryopreservation research method and operation process optimization together with the aid of numeric model of dynamic temperature transmembrane mass transfer.