I recently performed an experimental separation with 4 proteins in 100 and 10 mM KCl. All proteins are negatively charged at the pH of the experiments, and we would expect that less would pass through the membrane in the 10 mM KCl solution. Here’s the gel: You can see that the beta-gal in particular does…
With some of the recent high porosity membranes being produced, I wanted to demonstrate that we can use ALD to create a movable cut-off without sacrificing too much in permeability. I took sc713 and coated it with 5 nm and 10 nm of Al2O3 i.e. I shrank the pore diameter by 5 and 10 nm….
I’ve been working with the AFM recently and have had some success getting images on supported pnc-Si films. Yesterday, I imaged three samples from sc 698: one untreated pnc-Si film and two films coated with aluminum oxide (1.5 nm and 5 nm thickness). Here are the scans (500 nm x 500 nm). The topmost scan…
Today, I ran a quick experiment to confirm that water transport was not negatively affected by an aluminum oxide coating. I deposited 1.5 nm of Al2O3 onto a pnc-Si membrane which I then treated with an oxygen plasma in the YES system. I was curious to see whether the alumina coating along with O2 treatment…
Today while I was imaging a Al2O3 coated pnc-Si membrane on the high-res TEM, I noticed something curious as I placed the beam on a single pore for a few minutes. I was initially interested in the structure of the aluminum oxide coating, but found that something started to deposit on the pore walls as…
1) FIB. I tried to get a cross section of the pnc-Si with FIB with Brian’s help. The results are negative. It looks like the ion beam almost “melts” the membrane and destroys the pores instead of cutting. The tool also has in-built Pt deposition capability (from organo-Pt compound). So we tried to make the…
This is a quick post on comparing the contact angle after ALD on pnc-Si with aluminum oxide vs the untreated material (+/- ozone). The hypothesis is that the angle should drop since Al2O3 is hygroscopic. The angles are 85°, 45°, 61°, and 50° for the untreated, ozone, Al2O3, and Al2O3 and ozone case, respectively. These…
This is a follow-up to my initial report on using the ALD to coat pnc-Si pores with Al2O3. Below are the TEM micrographs and histogram of a series of depositions I performed with 3 different process times. I was targeting a 5 nm, 10 nm, and 20 nm reduction in pore diameter. The average diameter…
Today I made my first attempt at depositing aluminum oxide on pnc-Si using URInc’s Cambridge Nanotech’s Savannah 200 atomic layer deposition tool. Ritala and Leskela give a nice primer on ALD theory. ALD relies on layer-by-layer growth of film by reacting a precursor with the surface of interest. In this particular system, we react trimethylaluminum…
Charles developed a new microEO chamber, and I did some quick particle tracking experiments. The fluid in front of the membrane was filled with 200nm fluorescent polymer beads, and the power supply was used to cause the fluid to flow within the chamber. Bead speed was measured with Henry’s particle tracking programs. Picture of microEO:…