As mentioned in my previous few posts Justin and I have been working to characterize contact angles resultant from various exposures in the UV-Ozone system. Earlier this week we got our new oxygen tank installed and it appears that after using the 15min cleaning protocol (15min@150C with vacuum) noticeable decreases in contact angles can be…

In effort to understand the model, I have been studying simple diffusion experiments using rhodamine, a small molecule expected to experience little hindrance.  The model currently expects a small molecule the size of rhodamine to reach equilibrium within 1.5 hours.  In the following figure, the retentate is blue while the filtrate is green.   I…

Continuing the project that Mark had been working on, I have made some progress towards electroosmosis. Specifically, I was able to observe electrolysis through an intact membrane. Hopefully I will be able to observe electroosmosis through the movement of microspheres or nanoparticles through the capillary tubes. I tried a few variations of Mark’s design using…

This is an update of my progress with the diffusion model.   Sieving coefficients for standard setup (Renkin only) In this image there’s a strong sigmoidal curve for the 24 hour diffusion.  However, the cutoff (~34nm) is higher than cutoffs found in experiments.  The lower time curves have unexpected shapes.  This may be due to…

Last week I made a post showing the diffusion of DDM and BSA through SC267. I an effort to increase the negative charge associated with the membrane material I proposed using UV-Ozone exposure. A while back there was some concern that the UV-Ozone system was contaminated by PDMS, and that a standard cleaning protocol needed…

The purpose of this post is to see if there is a pattern in the Pore Density vs. Pore Radius graphs at certain manufacturing conditions. The following wafers all have widths of 15nm and RTPs of 1000. The porosities range from 6.48% to 8.33%. **** note: the y-axis label should actually read “pore density (#/nm2)”…

The goal of this rotation was to create a device to test the electro-osmotic properties of the membrane bound silicon chips. To perform this task, it was necessary to attach two glass pipettes onto both sides of a chip. The method required that the protocol be repeatable and easy to perform. Although it appears to…

Last week I made a post showing detection of detergent diffusion across membrane SC267. In the diffusion set up I had placed 6uL of a 50/50 volume ratio solution of 1.0% DDM and 1mg/mL BSA with 60uL of DI-water on the membranes backside. I allowed the setup to sit for two days and then used…

I’ve been thinking of demos/experiments to do with my upcoming class and one of them is SEM.  I was thinking of handing out some unknown nanoparticle solutions and have them figure out the size and maybe material by SEM, AFM and/or DLS. I’m approved to run the SEM now, so I hopped on today to…

Over the past few weeks, I have been trying to separate proteins with the SepCons. As a preliminary test, Barrett and I decided to first acertain that BSA could pass through a membrane with pinholes. Theoretically, the pinholes are so large that the BSA should easily pass through. However, it doesn’t appear that the BSA…