The current method of testing water permeability through SepCons is to place a volume of water inside a SepCon and spin it inside a centrifuge. After a set period of time, the volume passed is collected. The “approximate” permeability can be calculated as: volume passed/(pressure*area*time of experiment) in units of uL/PSI/cm^2/min. The reason this is…
We have a high school student, Nikita, (from my Summer Nanotech class) who is volunteering in the lab. Jim and I have assigned him the project of exploring diffusion of very small molecules through porous and putatively nonporous membranes. Currently, we are focusing on hydrogen peroxide (H2O2 = 34Da) and detecting it with the Amplex…
In the last production cycle, there were several wafers annealed for longer than our standard 1 minute RTP soak time. Recall in my earlier post, I observed a significant change in pore morphology in a 30 nm thick silicon membrane annealed at 1050 C for 1 min/5 min. In this series of experiments, we observe…
In this experiment, I wanted to test how quickly vacuoles form in endothelial cells when cultured on pnc-Si transwells. Here I used 30nm SC502 RTP’ed samples with the pnc-Si side down. I seeded P9 bEnd3 cells at 50000 cells/cm2 on the pnc-Si side, allowed the cells to attach for 2 hours and then inverted the…
This is a draft of a figure I think I’d like to use in my upcoming paper about charge based separations (this paper will include the Bernhard data). I thought I’d post it here first to get some feedback. I’ll first discuss the figure and then outline the problems that I see. Panel a. shows…
A while back, we discussed leaving the rotation stage off during the a-Si deposition to induce a thickness gradient over a single wafer. The purpose of this experiment was to explore the different morphologies vs. thickness at a given RTP treatment. We estimated that we could cover a 3x thickness range over a 8 cm…
In my last diffusion experiment, I used wafer SC 442. The results seemed to show that IgG was indeed diffusing through the membrane. As a follow up experiment, I am trying to show that I can pass IgG through more than just the one membrane. Furthermore, SC 505 has a much larger average pore size…
As I was preparing for the BMES conference, I took a few pictures of endothelial cells on pnc-Si transwells that showed extensive vacuole/endosome expression (here). The most dramatic example occurred on a 50nm-thick membrane that was barely porous. So I wondered – are cells responding to mechanical or porosity differences (or both, or something else)?…
The results of my last diffusion experiment regarding BSA and filtered IgG (using SC 364) were inconclusive. (See “Diffusion Test– filtered IgG and BSA”) Looking at the histogram of results, there is no clear difference between the absorption of filtered IgG and buffer A. For this follow up experiment, I used SC 442. Of the…
In my 1st post detailing glial cells on pnc-Si transwells, I saw lots of cell clumps above the membrane window (see here). Since these cells were grown in the wells, I thought they could be piling on top of each other in the wells and getting trapped. Here, I decided to flip the sample so…