An Experimental Study Of Non-newtonian Flow In Microchannals

Non-Newtonian liquid is a kind of liquid that does not obey the Newton's law of viscosity.They can be either natural or artificial.Blood and polyacrylamide solution,while both being non-Newtonian,is natural and artificial respectively and their microstructure differs greatly.In this article,these two liquids were both engaged in the experimental study of the flow characteristic in microfluidic chips.Some patterns showed in the flow process were analyzed and concluded.The main contents of this article are as follows:1.A platform on which flow experiments in the microfluidic device can be conducted was built.All sorts of needs such as conducting,controlling,observing,recording and pressure measuring can be fulfilled on the platform.Such was the preparation for the flow experiment of blood.2.PAM solution were used in the flow experiment in a single micro-tube powered by pressure.The results showed that the driving pressure had to reach a certain threshold to actually drive the flow in the micro-tube if the diameter of the tube is small enough.This pressure threshold had direct connection with the average molecule weight of the PAM.Meanwhile,other parameters that would affect the characteristic of the PAM solution were discussed.After that,a numerical pattern between the driving pressure threshold and the mass fraction under a certain condition was concluded from the results of the flow experiment,and the causes of this pressure threshold were discussed.3.A kind of microfluidic device was designed and fabricated based on the real parameters of the vessels and the characteristic of the vessel network extracted from the analysis of both shape and structure of the vessel network inside tumor tissue.Red blood cell(RBC)suspension was engaged in the flow experiment replacing the whole blood after the reliability of doing this was checked.in consideration of difficulties in controlling the experiment,sequential image of the flow was acquired as the result.RBC velocities,along with the relationship between the flow characteristic of the suspension and the hematocrit,inlet flow rate and size of the micro channel,was obtained.Some kind of regular patterns was concluded.4.Morphological analysis was conducted on the structure of the artery network of the retina,characteristics of the network was extracted.That combined with the parameters of the real arteries grants access to design two sets of microfluidic device mimic the typical structures of the artery network,four kinds in total.Flow experiments were conducted utilizing these two sets of chips.The results were processed and checked for the flow characteristic of the RBC suspension.Fahreaus Effect was observed?Cross-validation of the results was conducted,based on the function given by Fahreaus effect.