One of Christine’s projects was to determine if pinholes affected electrical resistance (TEER) measurements.  She summarized her work here.  I collected her data and did some negative controls to finish this work up.  Here’s the graph: The “no membranes” data…

Separations were performed at 2 different salt concentrations with equal volume filtrate and retentate (to avoid dilution problem). Separation time was 40hrs rather than the usual 24. The lower salt concentration run has a lower cutoff – which is just…

Christine and I have been looking into whether the O-ring position affects transport through pnc-Si transwells.  The hypothesis was that the unstirred water layer under the Sepcon might be diminished by switching the O-ring from its normal position (“O-ring bottom”)…

UPDATED: More sizing characterization (see chart and figure below). We recently purchased our own gold ladder, and today I’ve done some of the initial characterization.  Particles come in 5, 10, 15, 20, 30, and 40nm.  Here are the absorbance scans…

Anant and I have been doing long-term discoloration experiments for the past few weeks.  We set up samples in “ideal” conditions – pnc-Si in transwells with pnc-Si side down, autoclaved samples and in the incubator (lower OH-).  The only non-ideal…

PDMS/membrane deflection was measured on Veeco profiler by JP and me. The main problem with this kind of measurement is that it is taken form the backside of the membrane and the walls need to be excluded from the measurement.…

In my last post, I concluded that switching the o-ring position from below the membrane to the top in the sepcon produced no leaks. The reason for this switch was to reduce the 1mm “dead-space” (created by the o-ring) that…

PES Membranes: I tested 100 and 300kD PES membranes from Pall. 5 and 20 nm particles were used in both water and 10mM KCl. I won’t show all of the data, but I didn’t see any particles in any of…

In these trials, I used TER to look at the resistance between membranes with different amounts of pinholes. Finding a trend would produce a quicker way to scan for pinholes as opposed to checking each slot on the wafer with…

The new electroosmosis wafers have randomly distributed chips with 1, 3, 6, or 9 .1x.1mm freestanding pnc-Si squares.  The idea is that we can use these to get a better EO rate vs. active area curve.  SC125 seemed to have…