My previous post outlined the results of a EQ format separations using membranes from wafer 319. I have followed up that experiment using the same membranes, but in a diffusion based separation. I separated 2uL of 9.3 mg/mL clarified brain extract using a reservoir of 60uL. I allowed the diffusion process to occur overnight, and…

There’s been some discussion on whether furnace-annealed-only wafers are more uniform than RTP’ed ones. Today, I looked at several samples from wafer 304 (FA 1000 C) at different positions along the y-axis. (0, 5) – 25kx (0,2) – 25kx (0,1) – 50kx (0, -1) – 25kx (0, -4) – 25kx There’s a clear change in…

We finally achieved a separation using the EQ format. 4 SepCons from wafer 319 were loaded with 500 uL of .93 mg/mL clarified brain extract. They were run at 1000 rpm (which we roughly figured to be 3.3 psi initially) for 2 hours. After 2 hours, I judged the flow through the membrane to be…

Here are the conversion ratios for the URMC TEM images (so we’re all using the same standard): 30kx – 0.39 px/nm50kx – 0.67 px/nm150kx – 2.2 px/nm300kx – 4.5 px/nm These numbers should be used for wafers 187, 189, and > 310. Unlike the RC TEM conversions, these numbers seem to be consistent between the…

Dave and I tested 8 wafers (187, 189, 310, 316, 318, 325, 327, 329) from the last 3 runs and traces of copper can be found within all the wells. However, the amount and position of this contamination varies greatly, with the most particles being located near the top of the well, away from the…

This is re-do of a post I made before the new year regarding the predictions of the ‘Tong equation’ for wafer 310 (I deleted the earlier post because I came to the wrong conclusion). I wrote MATLAB files to calculate the predictions of the Tong equation from porosity, pore diameter, pressure and membrane thickness. Also,…

Here is a look at all our water permeability through nanomembranes to-date. There appears to be subtle trends showing increasing permeability with radial position (r – values) and a not-so-subtle trend showing decreasing flow with protein (cyt and albumin). Note that with the more recent membranes we’ve been able to do repeats. The permeabilities are…

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…

I derived the governing equation for the volume transfer from SepCon devices in the wet/wet (EQ) format. It is … where the equilibrium volume for the cup can be calculated apriori using the cross sectional areas of the cup and the surrounding annulus … with the total volume of interest given by and the time…

This is probably not of general interest, but for the sake of full disclosure, I have spent considerable time working with our wafer supplier (Virginia Seiconductor) to resolve some issues regarding the surface quality of their wafers. It would have been much more productive to simply switch suppliers, but unfortunately, they are the only place…