I have had a chance to play with some of the chips from Lot 1278, specifically the design with the 2 micron slots. Results are a bit of a mixed bag. Wetting these chips continues to be a challenge. My first attempt to use the vacuum wetting protocol in ethanol resulted in a broken membrane,…
I’ve now made 18 pores in monolith devices, with only 1 real success, which was the first one that I report on already. All of the rest have failed for various reasons, mainly relating to the silicon nitride membrane in which the sensing pore is fabricated. The first issue is fabrication time. Fabricating a pore…
I have three monolith experiments to report, one of which was successful. In all three cases, I was able to make a pore, though it took about 5 times longer than it would have for the NPN-tented chips. This is likely a consequence of the reduced exposed membrane area in the monolith case, which is…
A quick recap: of the pores using the old NPN batch, 2 of them showed folding suppression. The first one I was able to collect events for 1000 and 2000 bp dsDNA, bnoth of which showed almost no folding, but had an unusually low event rate. The second suppressed folding for the first half of…
Just a quick update on my status: I got the NPN pre-filters from Greg in Montreal and finished testing 15 of them last week, so this week I will start doing additional experiments. I plan to explore the size separation capabilities in KCl, which should give even tighter distributions than LiCl. I don’t plan on…
First off, a quick update on the state of the lab. The day finally came, we had to pack up and put everything in storage, so unless there is a very pressing need, I’m done data collection for the time being. I don’t think that will be a problem; we have enough for publication as-is,…
Since my last update I have been trying to achieve reliable size-separation of DNA by length using dwell time with the NPN pre-filter. Originally I had hoped to achieve 250-bp resolution near the optimal length for the NPN filter devices that we are working with, but that turned out to be a bit overly ambitious,…
This update covers my efforts since our last skype meeting to show DNA size separation in a filter, as well as some very interesting TEM images of ALD-coated NPN and associated controls. Here is an inventory of my current chips: Oxide-spacer chips with nitride cap and no filter yet: 8 Oxide-spacer chips with nitride cap…
Just a quick update this time – since my last post I have been doing control experiments to demonstrate the effect of the filters. For the controls I have been using the chips without the nitride cap, since I am running low on the nitride ones (current I have 23 left, 7 with filters already…
Since my last update things have been going quite smoothly. Most pores I make are able to pass 3 or 4 samples before clogging, and I have filled in the various graphs quite nicely. I still would like to flesh out the low and high end of the DNA length spectrum, but I’ve started writing…