Study Of A Microfluidic Chip System Based On The Liquid Quantitative Shunting Mixing And Detecting

Microfluidic chips are based on the chips with a few millimeters,which are injected into the liquid which is to be tested with micro liter or liter capacity to complete a series of basic steps such as separation,mixing,reaction and detection.Microfluidics is a cross discipline of multi direction,which involves the specialties of chemistry and fluid.It can be used in the fields of biochemical analysis,instant diagnosis,screening and synthesis of materials,bionics of tissues and organs.The microfluidic chips can not only improve the speed of analysis,but also greatly reduce the cost of analysis and the consumption of samples.at the same time,analyze faster provides a great application prospects for analysis of trace elements.According to the principle of microfluidic drive system and micro-mixing in microfluidic chip and the requirement of research project,the whole structure and processing process of microfluidic chip are determined in this paper.The scheme is to realize the quantitative distribution of samples and reagents.Finally,the volume of blood particles was measured by impedance sensor,and the concentration of protein in blood was measured by absorbance.The quantitative flow distribution in microfluidic chip can be realized by two different technical schemes.Based on the capillary electrophoresis driving technology,the cross flow injection method is used to distribute the sample of microfluidic chip.The specific scheme is to use double cross channels to realize the process of quantitative injection and separation analysis of fluid by controlling the voltage and switching direction.The cross channel model was established by using finite element simulation software COMSOL,the boundary conditions of the fluid were set up,the coupled multi-physical field was applied,and the quantitative distribution process of the micro-fluid was simulated.The relationship between potential difference and separation efficiency and separation velocity is analyzed by comparing two groups of different data.The curves of the relationship between cross separation channel and sample concentration at different times are obtained.Another way is through the pneumatic valve to achieve micro fluidic chip micro quantitative fluid shunt.Since the two volume of solution to be mixed disparity,therefore the use of pneumatic Valveless Micropump driven on fluid shunt after quantitative were mixed in a micro mixer,mixing after impedance test and absorbance test,accordingly the microfluidic chip inside the micro channel structure design.The overall structure of the microfluidic chip is divided into three layers,including the upper cover plate,the middle layer and the lower substrate.According to the design requirements and material properties,the cover sheet and the substrate using borosilicate glass material,the intermediate layer adopts organic polymer PDMS chip.The structure of processing by photolithography,are sealed on the three layer structure by thermal bonding method.Based on the structure and driving principle of the valveless micropump,the size effect,flow velocity and flow resistance of the fluid in microscale are analyzed theoretically by using the COMSOL software,which is used to simulate and analyze the influence of the structure parameters on the instantaneous flow rate of the microfluid.According to the diffuser / shrink tube structure of the valve free micropump,the calculation formulas of flow rate,pressure and resistance coefficient are derived.At the same time,the flow field in the valveless micropump is simulated and analyzed,and different angles are obtained.The effect of length and width on the instantaneous flow rate under different pressures is analyzed.Finally,the mixing effect of the inner ribbed passive micro mixer is analyzed.Through the diffusion control equation of the fluid,the evaluation method of mixing and mixing performance is strengthened.The finite element analysis model of internal rib micro mixer is established by using COMSOL software.Ten sections with equal distance are intercepted on the model.The effects of different inlet velocity,diffusion coefficient and dynamic viscosity on mixing efficiency are simulated and analyzed.The curves of the relationship between each section and the concentration are obtained.