Permeance of a sample was first calculated by taking a TEM image of the membrane and extracting pore size histograms. The flow rate through each pore can be calculated and then summed to determine the flow rate through the sample. The flow rate is then normalized by the pressure and surface area to calculate permeance…
The samples of nanoparticles from the Barcikowski lab finally arrived after 9 days in transport. Regrettably, the ice pack they shipped with was completely dead, and it is possible that the samples were in some way ruined. After we received the shipment, I immediately ran a small amount of each sample in the DLS machine,…
The main difficulty with creating a simulation of the single channel dialysis chip is that the membrane is so very thin (20 nm). This is especially true when compared to its length of 10 mm but also when compared to the channel depth and permeate well (which in our case is actually a beaker of…
There is a reliability/handling issue with the single slot chips. 0.5 mm x 10 mm slots, 20 nm thick membranes with 40 nm SiN reinforcement. The membranes are easily packaged in an upper fluidic PDMS layer with inlet/outlets and two PDMS struts (on the membrane side to protect from accidental contact breakage.) The first test…
It is well believed that the pore formation is directly related to the silicon crystallization. In this post, I’m gonna further show that how does the crystallization process affect the pore formation. The crystallization process can be divided into two stages. The first one is the nucleation of silicon atoms. In this stage, crystal nuclei…
We have suspected that those non-open pores in the TEM image of pnc-Si are pits in the silicon membrane for a long time. Last week, I SEMed a sample, oxide (30nm)/Si(25nm)/oxide(30nm) annealed at 800C for 1min, to verify the pits features. The first figure is a TEM image which the majority feature looks like non-open…
In this post, pores from four different structures are compared. Those four different structures are nitride/silicon/nitride (NSN), nitride/silicon/oxide (NSO) , oxide/silicon/nitride (OSN) and oxide/silicon/oxide (OSO) . The thicknesses of nitride, oxide and silicon are 30nm, 30nm and 25nm, respectively. Wafers with four different structures were etched first to remove the substrate. The four different free…
It was speculated that the rate of diffusion through a charged membrane had a direct relationship with pressure – as pressure increases, the kinetic energy of the charged particles is more likely to overcome the electrostatic repulsion of the membrane, until at a high enough pressure the repulsive force is small enough to be ignored….
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…