My PhD exam was postponed (tentatively to early September but it’s up in the air still) due to an impending bureaucratic nightmare, so for the last few weeks I have been running more filter experiments, and I have discovered some interesting trends. While it is generally the case in nanopore experiments that the average dwell…
Warning: the following post contains spoilers for Vincent’s talk at Rochester on Monday. Since the last update, I have tried to get the gold nanoparticles working properly, with no luck so far. The zeta potential we measured in KCl was 0mV, showing that even though we had visual confirmation that there were particle suspended in…
From my last blog post, was talked about designing an assay whereby the NPN filter would exclude DNA-conjugated gold nanoparticles while allowing short DNA to pass. Since then, I (with the help of my colleague Dan Tassier) have been wrestling with gold nanoparticles to find conditions in which the nanoparticles were stable, while also allowing…
Since I’m now back pretty much full time on the filter project, I’ll give a quick update about where we stand and where I’m going with it, as well as some (negative) results from this week. On the membrane transfer side of things, we finally have a tool that can produce fine enough vapor…
The new oxide chips arrived this week, so I have materials for lots of experiments going forward. The current inventory stands as follows: ~100x NPN chips (mostly still in wafer form) 81x 20nm SiN + 200nm + 10nm SiN cap 93x 20nm SiN + 200nm oxide Imaging of the membranes shows the expected images for…
My last experiment did not go as planned, but the results are very interesting nevertheless, and might provide another interesting application for these tw0-membrane systems that we had not yet considered. The start of the experiment went as planned: painted PDMS on the chip, used additional PDMS to glue the gasket to the PDMS layer,…
I decided that instead of trying to figure out why it was delaminating, I would simply remove the option altogether.To that end, I painted PDMS on two NPN chips up to the oxide spacer. Attempt 1: This chip was one I laminated myself using my breath to contact the membranes. In case it’s unclear,…
I am doing a few more membrane transfers and trying to troubleshoot my delamination problems, and I wanted to run my protocol by you guys before I mess up any more chips. I was able to get about 3/7 transfers visibly very good without any wrinkles, but they all still delaminate, either during the fabrication…
Since the control experiments seem to be going OK I decided to try again with one of the NPN-tented structures that Greg made originally. Since piranha cleaning seemed to be making a difference I wanted to pre-clean the chip, but from previous experience with a couple of poorly-tented NPN chips as guinea pigs, the NPN…
A quick update since we last talked about how DNA controls were proving to be problematic: Things are working again (more or less). I went back top basics, remade most of my solution, ordered new DNA samples, and, most importantly, piranha-cleaned my chips. The first three experiments I did on basic 30-nm thick 5.4mm square…