Last week, we reported that it was possible to anneal membranes after they had been etched. Below is a summary of results from membranes that were annealed over a range of temps and under different conditions. w600 (20 nm oxide) w510X (40 nm oxide) amorph. anneal 700 C no defects no defects amorph. anneal 750…
As per Chris request, here is a photo with a brief description. Sorry the image is still not good… the surface of the plastic reflects lights and it is transparent, plus I am using a poor camera. But I hope the description is useful and anyway tomorrow we can check it out in the meeting!
Since Paul sent an email saying he will be on leave from this week, I spent some time in the hopeman metal workshop with Paul working on our second diffusion chamber before he leaves. We actually failed four substrates before we made it. Here is the enhanced version. First, we made the hole through the…
Last week Jess and I did some diffusion tests using the prototype chamber. We observed there was some fluorescence background noise from the plastic substrate. So we decided to make the buffer well (the hole on the substrate) all the way through the Polycarbonate sheet and seal the well with a slide. We can see…
Yesterday afternoon I made a new batch of 10:1 (base : curing agent) PDMS and put it in the oven at 80C for two hours to allow it to cure faster (compared to the three days it takes at room temperature). Once the PDMS was cured Henry used the UV Ozone system to again try…
W509X, with single 100um by 1000um slits, was tested for air permeability and burst pressure. Prior to testing, I inspected all membranes for pinholes.; every sample had pinholes on the membrane perimeter, as shown below. The first two images are in reflection mode (pinholes appear black) and the last is a transmission image (pinholes appear…
After posting my observed results from yesterday I came in today to find that one of the segment of the PDMS was strongly bound to the glass cover slip, so strong in fact that trying to remove it caused the cover slip to break. This result comes in response to the comment that Chris made…
Below are images from two samples that were annealed at 950 C and 1050 C post-EDP etch. The lower temp anneal produced a membrane with many features that do not seem to penetrate the nc-Si. There were a few (couple in each field) smaller pores ~ 10 nm in the outer samples. This supports Jess…
I talked with Jim last Friday about a second possible dialysis system using PDMS bound to a glass cover slip. I made a batch of PDMS and let it cure at room temperature over the past few days. Jim had suggested I try bonding the PDMS to a glass cover slip using the UV/Ozone system…
I tested four samples (-1,1); (-1,2); (-1,3); and (-2,4) for air permeability and burst pressure. The first three samples showed no measurable air permeability for three attempts each. The sample from position (-2,4) did have a very small air permeability of 11.2 cc/(cm2*atm). Based on the results of rhodamine diffusion it seems odd that I…