We have two cutoffs for the Millipore Biomax PES membranes: 50kD and 30kD. I tested the “EO” rates for both of these membranes and plotted them in this figure with standard deviations (3 trials of 50kD and 4 of 30kD).
50kD has a significantly higher rate of “electro-osmosis.” I will try to compare these rates to those found in the literature.
With the new heater installed in the AJA sputter tool, the production team decided to run a set of wafers at six different chamber temperatures to re-characterize membrane morphology, mechanical strength and overall quality of material. These films were all deposited with 25 W substrate bias and annealed at 1000 C in the RTP with…
In yesterday’s post I showed that I was able to obtain good negative adsorption assay results, but there was one major problem. The cellulose and PES actually had higher protein concentrations after the assay. I suggested this was because they are drawing in water to some extent, but protein was not able to pass through…
Recently, I have been trying to pass 5 nm, 10 nm, and 15 nm gold through untreated, carbonized, and ozone/carbonized membranes. These experiments were done in the pressure cell with fresh samples. I used a 1:1 dilution of Au stock and DI water. To wet the membrane I placed a 40 uL drop of water…
One area of use to explore for the membranes is desalting, the removal of salts from solutions (such as those containing proteins). Two dialysis products made my Thermo/Pierce were tested to develop a protocol and test manufacturer’s claims. These products are the mini-dialysis unit on the left and the dialysis cassette on the right; both…
My last experiment did not go as planned, but the results are very interesting nevertheless, and might provide another interesting application for these tw0-membrane systems that we had not yet considered. The start of the experiment went as planned: painted PDMS on the chip, used additional PDMS to glue the gasket to the PDMS layer,…
Hello Everyone, Kilean helped us to set a training session for NanoParticle Tracking Analysis (NTA) in UR Medical Center. For this training session, i had 4 samples including: Beads, Liposomes, Media + 10% serum, and PBS. Here is a summary of what we learned, i am also summarizing a paper that i found for comparing…
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How does this compare to pressure driven flow rates for these membranes? I’m curious about whether there is a bigger EO push, or just less resistance. This difference is interesting though, so the similarity in PES and cellulose flow rates may just be a coincidence, or related to cutoff….
Here’s a rough calculation:
In pressurized flow our membranes are on the order of hundreds of ul/(min*cm2*psi) and PES membranes are tens of ul/(min*cm2*psi) at same pressure.
My EO data shows pnc-Si are about 7 ul/min. If we normalize that to active area (.004cm2), we have 1750 ul/(min*cm2).
For the PES the 50kD value in this post is 3 ul/min. The active area of PES (when you remove anything blocked by the o-ring) is about .43cm2. Normalizing 3ul/min with this gives you 5.17 ul/(min*cm2).
This is a huge difference! In fact EO seems to give us an extremely high rate of transport even when compared to pressurized flow. The next thing for me to check is probably the relationship between driving voltage and EO rate.
Correction:
For PES diameter is .43cm, area is .145cm2, and flow rate is 20.7 ul/(min*cm2).