w302 Permeability
Wafer 302 appears to have no pinholes and held up pretty well in the centrifuge, up to 5psi for many hours in a wet-wet format.
Here are some quick numbers on flow rate over 2 hours, 3.3psi, including radial position:
1x PBS (no protein)
68 uL (r=4.1)
91 uL (r=4.1)
99 uL (r=4.5)
Using Jim’s new equation. 99uL of passage of PBS in 2 hours results in a permeability of almost 190 uL/(cm2-min-psi).
2mg/mL Cytochrome C in PBS
11 uL (r=3.6)
11 uL (r=4.2)
24 uL (r=4.1)
After the two 11uL samples finished running, I quickly measured then re-loaded them with more material for a second run. This time the cytoC conc was 1.2 mg/mL. I ran them at a higher pressure of ~5psi over 22 hours. The first broke, but the second ended up passing an impressive 112uL. This is not much lower than would be expected if there flow is directly proportional to time and pressure, suggesting protein clogging or closing of the pores was not a significant problem.
There does not appear to be a strong correlation between r-value and the variation in the above measurements – although there was not much range in the r-values. The TEM images for this wafer show a surprisingly different porosity in pictures of 0,3 and 0,4.