We have successfully plated adipose derived stem cells (ADSC) on microporous silicon nitride (SiN) membranes. Cells plated on nanoporous SiN appeared fine at time of seeding, but membranes were broken at 2 hours – possibly due to media washing or cell spreading/contracting. Josh Miller made new Microporous and Nanoporous Nitride liftoff membranes. These membranes were…
After a false start with non-microporous TEOS chips, I quickly did an image comparison with truly porous chips using polystyrene beads. The TEOS and Silicon Nitride chips were both fabricated in the single-well CytoVu format (single 2 mm window, 5.4mm die size). The TEOS chips allows water and media with serum to much more easily…
We have re-started the PEG x-linking project at RIT. One of the goals is to create microwells made of PEG on top of a membrane in order to culture individual cells or small colonies of cells with the potential for a co-culture with a confluent monolayer on the opposite side. PEG is available as PEG-Diacrylate…
A group published a paper in Lab on a Chip (2012) using track-etched membranes for electro-osmosis. There are a lot of eerily familiar terms and concepts in the paper. The title even sounds familiar: Low-voltage electroosmotic pumps fabricated from track-etched polymer membranes They created a device with metal mesh electrodes on the opposite sides of…
To follow up on some of Dave’s work – I was curious if the ALD alumina affects the strength of pnc-Si membranes. Punchline: 2.5 nm of Alumina seems to increase the burst pressure, while 5.0 nm reduces the burst pressure. Methods: As part of routine QC, we had already measured robustness on 6 SepCons to…
Dan Mendelson performed gold separations using wafer 255 and has shown that this wafer has a cutoff for gold near 25 nm. Below I have plotted the data of filtrate gold concentration as a function of the feed concentration for the three wafers we have tested. The bottom panel is a replot of the Malvern…
I continued work with a couple of new wafers and settled on one that lowered the cut-off to between 5 and 10 nm gold particles. For completeness, I will also include some of the old data that has been further analyzed. All experiments were performed with BBI stock gold solutions (0.01% w/w?) diluted 1:1 with…
Motiviation and Background: Nakul and I have been performing a lot of DNA filtration and attempted DNA shearing experiments. We found that large DNA fragments (>1000 and >2000 bp) pass through ~30-40 nm max pore size membranes when pressurized to 10 psi (even in low salts). This is in contrast to the Bernhard data where…
So I think I have confirmed that PDMS is at least one of if not the major contributor to the contact angle problems in the UV-ozone system. Control image before any treatment: I then dried the chip and placed it in the UV-ozone system with two slides that each had two strips of PDMS. Since…
Nakul and I noted last week that the UV-ozone system was not performing. We took pictures of control and treated samples (2x) to measure contact angles on Amorphous, pnc-Si, Oxide and Nitride TEM grids. Our results were pathetic – most samples had less than a 10 degree decrease in contact angle, staying near 60 degrees….
