Design And Verification Of Microsecond Mixing Microfluidic Chip

Microfluidic technology has been rapid development in the field of chemical engineering,biological engineering,and detection/analytical process because the diminutive scale of the flow channel increases the surface to volume ratio,and beneficial for many applications,such as chemical synthesis,and transport phenomena on the microscale.Fast mixing is essential in many biochemistry analyses,such as cell activation and protein folding,which require rapid mixing reactants,so the micromixer become an important component in a microfluidic system.A passive mixer with the obstacles are symmetric distributed in the channel is simulated,the reasons for producing mixing and limitations in the mixer are discussed.For solving the limitations,a new structure called cascaded splitting and recombination(C-SAR)is proposed.The new structure has greatly improved the effect of mixing.It can get a good mixing performance at Reynolds number range from 34.6 to 147.7 with sub-millisecond mixing time.Using PDMS(polydimethylsiloxane)as chip material,the chip was fabricated by molding method.Rhodamine B and DI water are used to validate the mixing performance in the C-SAR mixer,the result of experiment is good agreement with the simulation results.In addition,in order to achieve microsecond mixing time for micromixer can be applied to most experiments that require rapid response.A new type of C-S mixer is proposed.This mixer can get a good mixing performance at Reynolds number range from 16.6 to 100.In aqueous solution,mixing time is 44?s when Reynolds number is 100,at this time,the total flow rate is only 1.5?L/s.Moreover,in the theory the C-S mixer can have a complete mixing with the total flow rate is 8?L/s when the viscosity of fluid is 30cp,and mixing time will short to 8.25?s.In the validate experiment,the result of experiment is slightly below the simulation results,but it also meets the standard of full mixing.In the viscosity adaptation experiment,the solvent of Rhodamine B solution is replaced by a glycerol solution of 20%mass ratio,the result shows the good mixing performance is reach when the total flow rate is larger than 1.25 ?L/s.it shows that the mixer has a certain adaptability to the viscosity change of the solution.