Last week I reported that carbonization can shrink pores.  This week I was able to completely occlude the pores with a change in the process recipe.  Instead of cutting off the acetylene flow before the thermal treatment, I kept the gas on for the entire process.  What resulted was a complete occlusion of the pores….

I reran the samples from this post on coomassie stained gels.  The sensitivity is lower, but the results look reasonable. First off I check out how well the sum of the retentate and filtrate matched the starting sample.  This was much closer with the 100mM trial.  There seems to be more error/loss in the 10mM…

Dave did a series of 20nm SiO2 film depositions at different temperatures (constant bias) and gave them to me to AFM.  I guess he wanted to see if film roughness changed drastically over the range of ‘room temp – 400C’ in order to investigate this as a potential source of pinholes. I used a new…

In this gel I evaluated the linear range of coomassie brilliant blue. From this test it looks like things are linear from .0156 to .125mg/mL.  My guess is that the protein ladder bands in the previous experiment fall within the range. I used the Bradford assay to find the total concentration of the stock protein…

Previously I have silver stained all gels because the separations look very clear with this staining technique.  However, the silver stain is not giving very quantifiable results.  Coomassie staining means a loss in sensitivity, but it’s the gold standard for quantifying protein amounts.  Here I’ve stained one of the protein separation results and rerun with…

I’ve always wondered what the variability was in the pore statistics extracted from TEM images of different fields on the same membrane (SC 141).  I took a series of ten images from random positions (corners, edges, center) and ran them through the pore processor.  Here are the results: (images taken at 100 kx) position porosity…

After some experimentation with acetylene concentration and anneal temperature, I was able to find a carbonization recipe that appears to shrink our pores by 1/3 the original diameter.  Below are images of an untreated sample (TEM 148: 15 nm pnc-Si 1000 RTP) and a carbonized sample (see recipe at end of post). A closer look…

Before Anant left for India, we were doing cell adhesion studies with pnc-Si transwells and getting some weird morphologies.  Check it out here, here, here, here, here. This is in contrast with the 2D studies that Anant did for the cell culture paper in which cell adhesion looked good.  The main difference is the transwell…

First, last week I had some images taken with new “visiting” AFM. These were frontside of the membrane with parylene deposited from the well side and the front side with deposited parylene on it. 1-1. Parylene deposition was not successful and although the dummy wafer showed thickness of parylene about 22nm, I suspect the were…

Earlier this week, Maryna and I did some AFM of her samples.  She vapor-deposited parylene on the well-side of pnc-Si and was interested in whether/how well that polymer got through the pores.  We got some really interesting-looking scans, but I’ll let her post those images. As controls, we looked at clean chips from the same…