I tested W612 for air permeability and burst pressure, shown below.
It should be noted that the air permeability and burst pressure values are comparable to W504; looks like a good reproduction! I also tested a sample with the hexane residue and debris, no difference in permeability or burst pressure was seen.
Background pores included (0,0)
Background pores removed (0,0)
Background pores included (0,4)
Background pores removed (0,4)
I have been developing a microsystem for Paul Dunman’s group that will allow them to flow in bacteria, immobilize them on antibodies, and then subject them to varying concentrations of antibiotics. The full system will incorporate a fluidic mixer and a NPN membrane as a way to introduce the antibiotic I have been working with…
Katia in Dr. Shestopalov’s Lab functionalized some pnc-Si windowless chips. The process she follows is shown in Figure 1. She provided chips at various stages of the process. “Grignard”, “Diazirine”, and “PEG”. After functionalization, the chips were wetted with 20 µL of 1:1 pbs then 40 µL of 5 mg/mL f-BSA was added. The…
SU-8 3010 has been used to create a scaffold in the fabrication of the liftoff membranes. The supplier of the negative resist, MicroChem, rates it for a 13 moth shelf life. We were having difficulty achieving good liftoff with membranes in the second half of last year. The SU-8 had expired by several months, so…
These are the sieving curves for 50, 75, and 100 nm NPN membranes. The 75 nm NPN 30 nm gold data point is just an estimate, since the membrane broke before enough filtrate could be collected for an absorbance measurement. However, our estimates of zero gold tend to be pretty good (gold is very visible in solution,…
The last post I made about the BSA/DDM separations using “treated” and “untreated” SC269 samples explained a problem I was having in which the initial retentate drop was diffusing around the edge of the sample chip. It seems that SC269 is naturally more hydrophillic than SC267 therefore when “treated” it becomes so hydrophillic that the…
This is a short review of a few experiments that Tom had set up this morning. Carbonized membranes: A few carbonized membranes that were used for permeability measurements were tested in EO. The membranes were left in the sepcon, which was filled and placed in a reservoir. Electrodes went inside the sepcon and the reservoir. …
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Was there anything different about the membranes you burst tested that failed ~2-3 PSI? Debris on the edges, perhaps? I also think you meant to say that w504 had a cutoff of ~29 nm.
There was no debris on the membranes with lower burst pressures, one of them did have the pentane spots however. I also tested another “spotted membrane” and this had a BP of 7. I did mean 29nm, sorry.
I think we should produce histograms w and w/o the background ‘pores’ and show size-by-side images of the original TEM and the one with pores outlined. This will allow folks to make their own judgement and use the numbers they trust for their purposes.
I added histograms with and without background pores, along with the images used to create them.
The image for “(0,0) background pores removed” is the same as “(0,4) background pores removed”.
Fixed.
What do you do to remove the “background pores”? I see changes at many pore sizes in the histograms, so you are not just using a size cutoff…
Also, if the flow rates are correct, many of the small pores must be open, since there are large differences in the density of the biggest pores… How do these measurements compare to Maryna’s theory – Maryna?
All I did to remove the smaller pores is change the threshold, though I realize now that I should assign a cutoff, as changing the threshold changes all the sizes.
Yeah, I’m not sure how to best make this adjustment, there are arguments for both thresholding and applying a size cutoff. Obviously, the objective to to most accurately reflect reality…