Hi all, Previously we described a two-compartment flow system integrated with a nanoporous membrane in between; and we showed that the nanporous membrane effectively reduces fluid flow from one compartment to the next. Seeing that today is our last NRG meeting this summer, I will present a revisit to the prediction of flow distribution within the membrane-based…
Hi all, During last NRG meeting some questions are raised on what is the transmembrane pressure in Dean’s chip-in-a-beaker dialysis system and what is the direction of flow of the whole system. i gave them some thought and proposed the following scenario. Please feel free to correct me should I made any mistake. i am simply throwing…
Hi all, A while back (in the link below) I have posted the analytical solution that allows us to solve the flow rate distribution in our shear-free system. shear stress reduction via pnc-Si: analytical solution However we do not have a closed-form solution at that time. After a brief discussion we believe that there should…
One major problem that we faced with our current shear-free chemotaxis system is the lack of high image quality. Since the silicon-nitride (SiN )grid is 100 um away from the coverslip surface on which the cells migrate, the out-of-focused SiN grid blurs the image. This makes cell tracking much harder. An example of a movie…
To assess how shear-free our [ “shear-free” chemotaxis system] is, we tracked the motion of nanoparticles in the shear-free compartment as we input a known flow rate in the flow compartment. The nanoparticles we use are the 210 nm dragon green fluorescent beads. ==================================================================Following is a 6-min long movie of the nanoparticles flown at a flow…
Hi all, We have already showed in our earlier [ post ] that our shear-free chemotaxis system can indeed elicit chemotaxis, suggesting that we have successfully translated a gradient through the membrane to the shear-free side of the system where the cells reside. However, it is still nice to show via fluorescence how the translated gradient looks…
Hi all, this report will serve both as an update and a template for my upcoming BMES 2012 poster on the shear-free chemotaxis system. Introduction: Because of its capability in hosting reactions and transporting materials in small volumes, microfluidics enables the efficient processing of precious reagents. However, the shear stress inherent in the use of…
Hi all! Last time we have presented a theoretical perspective on the shear stress reduction enabled by our shear-free microfluidic system. This time we will show an agreement between the shear-reduction predictions made by the analytical solution and a COMSOL simulation. For details on the analytical solution please refer to the following post: [https://trace-bmps.org/datablog/2012/04/26/shear-stress-reduction-via-pnc-si-analytical-solution/] COMSOL…
Hello everyone, presented here is a theoretical perspective on the shear stress reduction enabled by our shear-free microfluidic system. Briefly speaking, the shear-free microfluidic system consists of three main components: a flow compartment, the pnc-Si membrane, and a shear-free compartment. The membrane attenuates the fluid flow from the flow compartment to the shear-free compartment while permits…
Hi all! Above is an image of the bioreactor made from the square, 5-slit pnc-Si chip and a PDMS structure. Fused-silica capillary tubings were inserted into the bioreactor to form the inlet and the outlet for the transfer of the cells into the lower compartment, which is made entirely out of PDMS. Note that the…