Construction And Analysis Of Acoustic Micromixer And Liver-mimic Tissue Based On Microfluidic Chip

As a new science and technology which involves many subjects and fields,microfluidic technology has developed rapidly in recent years.Microfluidic chip has advantages,such as low sample consumption,simple operation,high degree of automation and integration,short reaction time,and high analytical sensitivity.Because the structure and size of microfluidic channels are similar to cells and organisms,more and more researches in microfluidic field are processed for biological research.Utilizing microfluidic technology,spatiotemporal control can be realized on a micro-scale.The fundamental investigation can be carried out in microfluidic chip from solution-to particle-level,and cell-to tissue-level.Based on the microfluidic technology,combined with acoustofluidic technology and pneumatic valve technology,we constructed an acoustofluidic mixer and an integrated microfluidic chip,which are used to realize the rapid mixing of solution and the construction of liver-mimic tissue model,respectively.Compared with other acoustofluidic mixing devices and in vitro liver tissue model,the acoustofluidic mixer has the advantages of continuity,stability and reusability,and the liver microtissue model has more complex three-dimensional tissue morphology and physiological characteristics.Our results provide new ideas for the study of molecular interaction on the chip and liver tissue engineering.The results of this research are as follows:1.A microneedle-based in situ mixing acoustofluidic device was designed and fabricated.The acoustofluidic device consists of two piezoelectric transducers and a microfluidic chip.Under the actuation of electric signal,the piezoelectric transducers can generate acoustic wave to act on the microneedle structure in the chip,resulting in the local vortex flow around the microneedle structure,which is used for the mixing of solution in the channel.In the research,the influence of microneedle structure,driving voltage and driving frequency of piezoelectric transducer,total flow rate in channel were evaluated in experiments,and verified by quantitative calculation.The mixing condition with the best mixing effect was obtained and the fast mixing in millisecond-level was achieved.Then,by the fluorescein mixing experiment and fluorescence quenching experiment,the excellent performance of the mixer in the field of in situ mixing and chemical reaction application,such as continuity(100 min continuous experiment),stability(200 on/off repeated operation and stable temperature in experiments),reusability(22 days repeated use),were confirmed and proved.Next,by up-grading the design of the chip,a mixer with the function of concentration control was prepared and verified with excellent mixing effect.Finally,the product formation model of enzymatic reaction in laminar flow mode was simulated and verified.The calculation method suitable for the evaluation of enzymatic reaction rate was proposed.The kinetic constants of the enzyme were calculated by measuring the enzymatic reaction in different substrate concentrations.All the results confirmed this acoustofluidic device suitable for investigation of different instantaneous chemical/biochemical events associated with various molecular interactions and reactions for applications in molecular science and life science.2.An integrated microfluidic chip was designed and fabricated for the construction of liver-mimic microtissue unit.The integrated microfluidic chip consists of four layers: fluidic layer,control layer,support layer and glass slide layer.The interaction between the inner patterned valve and the outer patterned valve designed in the control layer is used to prepare the liver-mimic microtissue unit.In this research,the driving pressure of the inner and outer patterned valves were tested,and the results showed that the pneumatic control system works well and independently.Then the function of microchamber modification in the construction and recovery of liver-mimic microtissue units was explored.The result showed that the cell pattern could be realized and the liver-mimic microtissue units can be recovered in the microchamber with gelatin modification.The cultured liver-mimic microtissue units have good cell activity and can simulate the microstructure of the liver in vivo from the morphological and physiological point of view.Finally,using the stacking method to assemble the liver-mimic microtissue units,the liver-mimic microtissue block can be obtained.The fabricated liver-mimic microtissue block has good cell viability and similar to the liver tissue morphology in vivo,indicating the potential to reconstruct the morphology and function of the liver in vitro.All the results provide a new idea and method for liver tissue engineering in the field of regenerative medicine and personalized medicine.