I’ve been taking lots of zetapotential measurements with my current setup. Serendipitously, it appears that the more I use the electrodes, the more stable my zetapotential measurements become. Because the system seems well behaved now, I decided to move on to…

Last week Sarah and I made several standard nanofluidic transistor (NFT) stacks (3 nm Ti, 12 nm Ag over a 3-slot SiN membrane – wafer # 1024) in the cleanroom. I then measured the zetapotential of these devices at pH 7.43,…

This paper (SiN paper) by Ulrich Rant et. Al. details several experiments conducted with a single pore drilled through a SiN membrane via TEM. They measure the relationship of pH vs. zetapotential for both a model protein (avidin) and their…

The blue line reflects measurements taken with my zetapotential setup. Each data point is the average of three independent measurements of zetapotential (a new 3-slot SiN wafer 1024 chip for each measurement) and the linear fit for the pressure vs.…

I’ve been going to considerable lengths to try and get reproducible zetapotential measurements from my streaming potential device. Zetapotential measurements are the closest we can experimentally get to measuring the surface charge of a membrane, and are important for three…

This paper (Variance of Streaming Potential) examines the sources of error in zetapotential measurements. Jess and Zydney both cite it in their EO papers as a source of experimental procedure – in particular this paper found that waiting for the…

This is part three of a series of posts on constructing a mathematical model of the movement of gold through a porous membrane. In part one, I implemented William Deen’s mathematical model of the electrostatic and steric effects that contribute…

Prior to my qualifying exam about a month ago, I put together a simple model of transport (detailed in this previous post) across a nanomembrane that incorporated electrostatics as well as terms describing both convective and diffusive transport across the…

UPDATE: I have since ported the program into Matlab. If you open the following zip document(Archive) you can run Find_Sieving_Coefficient. You can select a results file and after ~5 minutes the expected sieving coefficient for the pore distribution is spat…

I’ve spent a long time in lab trying to optimize the protocol for streaming potential measurements. The slope of an applied pressure vs. streaming potential graph can give us the apparent zetapotential through the helmholtz-smolachowski equation. The apparent zetapotential is…