I don’t think I ever posted it on the blog, but two years ago I discovered something neat. At the time, I was trying to make my nanofluidic transistor, and I was reading Marina’s thesis. She tried to improve the efficiency of our EO pumps by putting silver films directly on the front and back…
Two years ago (blog post), I asked Professor McAleavey to help me see if we could use NPN chips to generate ultrasound. I’d found a paper (An exact solution of AC electro-kinetic-driven flow in a circular micro-channel) that suggested, given the geometry of our chips, that if the chips could be used to generate sound, they’d…
I’ve been trying to make the following device work for the past few years: The people who have been studying this have been trying to use the phenomena to mix solutions, or using arrays of mismatched electrodes to generate a sort of conveyor belt pumping mechanism: My idea is to use the electrokinetic phenomena of AC…
I’ve been working hard on my model paper for a few months now. My first attempt at doing separations with Track Etched (TE) membranes, which are all 6um thick and come in pore sizes of either 30 nm or 50 nm, resulted in data that was all over the place: Note that the gold concentrations are…
We’ve known for some time that the sieving coefficient of our membranes changes over time. The reason for this is that at the start of the separation the concentration just above the membrane is the same as the bulk concentration, but as more and more fluid begins to pass through the membrane we get concentration polarization, and the membrane…
In my earlier posts, as well as in Josh’s NPN paper and Tom’s ACS nano paper, we’ve talked a lot about the resolutions of nanoparticle separations. What we mean by it is how well the membrane is able to discriminate between two similarly sized particles. For instance, we predict that a series of gold nanoparticle filtrations…
After correcting a minor error in my code that was giving me some weird limiting behavior, and optimizing the code to give me faster results, I generated the following curves: Note that, as experiment predicts, the ‘sharpness’ of the graph increases with increasing applied pressure. The model isn’t exact, and slightly underestimates the actual sieving…
The below figure has three different sieving curves. Solid lines are model calculations assuming a SiN membrane with 37 nm pores, and either 0.4, 1.3, or 5 PSI applied to drive the separation. Markers are real data. Note that the experimental data reflects the pressure-dependence of the curve, but is slightly different in concavity from…
I made a size ladder of ALD-ed chips. The chips I began with were ~35 nm average pore size, and I applied 2, 5, 7, 10, and 12 nm of alumina using the ALD in UR nano. This does represent an incomplete data set – the 7 nm and 12 nm alumina chips I first…