In an attempt to improve membrane life in cell culture, different RTP times were tried on a single wafer. Samples from W514 were RTPed in Ar at 800C for 1, 5, and 10 minutes, respectively. Cells were then seeded at confluence on membranes, with membrane stability monitored for breakage. Discoloration was monitored on samples without…
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…
I am in the process of inspecting each membrane in the newly created wafer 612. First of all, some samples (~10% counted so far) have tears on the membrane edges, shown below. Images were taken at 20x microscope magnification (reflection image followed by transmission). I also have been seeing circular defects which do not penetrate…
Last week I ran cell culture growth experiments on RTPed (800C 5 minutes in Ar) samples from W567 (single slit 100um x 1000um). For this study I tracked discoloration w/cells, membrane stability w/cells, and the bead assay w/cells to see if we can predict if a membrane used in cell culture is intact by monitoring…
I recently received three pinhole-ridden wafers for cell-related experiments. All three have been RTPed at 800C for 5 minutes in argon, which is the typical procedure we have been using for cell culture. The bursts pressures for each wafer are shown below. W520 is weaker than 558 and 559; I plan on using the stronger…
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 recently received wafer 567 from Dave for cell culture work. It has many intact membranes but is riddled with pinholes, having only 3 pinhole-free samples. I decided to test them for air permeability and burst pressure, shown below. I also noticed some odd features on the membrane and surrounding Si. They are circular but…
I recently tested W510X and W600 described by Dave here for air permeability, rhodamine diffusion, and burst pressure. No air permeability was observed; even a sample with one very small pinhole (W600 800C anneal) only had a permeability of 11 cc/atm*cm2*s. To verify the lack of pores I performed rhodamine diffusion on the W600 700C…
Desalting of 4M NaCl in deionized water was performed using our membranes in the SepCon format. I ran the SepCons in the same as way as the previous study, using a low stir rate and floating the SepCons. Once again, a conductivity probe was used to measure the amount of salt in the dialysate. Transport…
W509X, with single 100um by 1000um slits, was tested for air permeability and burst pressure. Prior to testing, I inspected all membranes for pinholes.; every sample had pinholes on the membrane perimeter, as shown below. The first two images are in reflection mode (pinholes appear black) and the last is a transmission image (pinholes appear…