Hi all, After nearly a month of troubleshooting the fabrication of Whitesides Chamber we finally have the capability to generate a steady and linear gradient of molecules. In the presented case, we have generated a gradient of rhodamine 6G (R6G), which is a fluorophore that allows us to visualize and confirm the existence of the…
As mentioned previously intact membranes show a flux comparable to membranes with pinholes during desalting experiments. To confirm this a third intact membrane test and two pinholed tests were run under the exact same conditions. Previous pinholed samples had different NaCl solution volume in the SepCon, I wanted to remove any variability caused by this….
A few weeks ago Dave dropped of a humidity monitor for the third floor equipment room. Since then I have been recording the humidity every time I run a UV Ozone process for PDMS-glass or PDMS-pncSi bonding and there seems to be a correlation between the two. Over the last week there seems to be…
Yesterday I started a test to try and reproduce the results Henry was able to obtain with a closed flow system last week. Using four samples (W619) I ran the UV Ozone bonding process and allowed them to sit over night. This morning I found that only one of the four samples was bonded; recently…
Just an update on the closed flow systems I put together yesterday using vacuum grease. Even with the vacuum grease at the point of entrance of the capillary tube to the PDMS-pncSi system the PDMS was able to get into the trough of the membrane chip. I will talk with Henry today to see what…
Introduction One area of use to explore for the membranes is desalting, the removal of salts from solutions (such as those containing proteins). Ideal membranes have uniform pore distributions, high mechanical strength, tunable, sharp pore cutoffs, and high porosity. In this study intact samples from W565, which showed no air permeability but allowed rhodamine to…
Just an update on the PDMS-pncSi closed flow systems progress… The issues we were having early last week with bonding seem to have been solved. We used to run extra ozone flow for ten minutes after the initial 5minutes of UV Ozone. As it turns out this is unnecessary, we are able to get nearly…
In continuation of the desalting work, I ran three additional controls: a SepCon with no slits (negative control) and direct addition of 4M NaCl producing final dilutions of 1:400 and 1:600 (these are the experimental final dilutions I have been working with). The results are shown below. I also calculated the flux for each condition….
I was having trouble using the spectrometer to measure rhodamine concentration in the stir cell. I ran a standardized absorbency of the serial dilution of rhodamine. The curve is posted below. It appears to be linear. The molarity of rhodamine must be above 2uM in order for the spectrometer to read it. I think I…
Lingyun and I used the stir cell and spectrometer to measure the diffusion of rhodamine across the membrane. This was the first time I was able to construct an experiment in the stir cell while keeping both membranes intact. In the past one membrane would rupture or the cell would leak too much. For this…