Overview: The study of ADSC spreading on various surfaces was conducted to determine if porous surfaces and the porosity of the surfaces had any effect on cell spreading. Eight different surfaces were studied and each of the membranes were SiO2, these included: 0.5um low porosity (LP), 0.5um high porosity (HP), 3um LP, 3um HP, 5um…
As part of the ongoing study of NPN membrane filtration characteristics I used the SEM to look at membranes after they were used. Unless otherwise indicated, files with a “t” (top) indicate the chip was membrane side up. “b” stands for the bottom, or trench side. In a standard forward centrifuge setup we expect the…
UPDATE: Some data presented here is out of date. For up-to-date data, see my next post here. — Lately I’ve been performing comparison experiments between our NPN membranes (wafer 1132, 3 slot SEPCON, 40-48nm pores and 13-20% porosity) and commercial cellulose triacetate filtration membranes, with respect to the degree to which they hinder the diffusion…
Last week, I worked with Kevin to create a prototype cell culture device that could be compatible with his Raman system in Nottingham. The space constraints of the physical system are challenging: The overall working distance of the system must be less than 1.5 mm (smaller is better), must maintain only MgF2, media, and cells…
In this post, I’m going to discuss the results of the different PEG molecular on silane samples. We used same condition to make 4 chips for each sample. And we treat them with BSA, IgG, and PBS to rest the adsorption. We are using the SEM, contact angle and XPS as the testing method. The way we…
The following plot is an attempt to summarize recent work measuring rate of flow through a membrane as a function of concentration. We investigated 100 nm NPs, (totally blocked), 20 nm NPs (partially blocked) and IgG (mostly passed). In all cases, the buffer used was 1xPBS and 0.1% Tween 20. This plot mostly shows the total…
Our recent work using NPN to separate free IgG from 20 nm NPs has shown that we can pass liquid under either forward or reverse configurations using the centrifuge. We had thought that there would be greater resistance in the forward orientation due to cake layer formation. We had found high resistance to flow in…
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 a more difficult problem. Sarah and I made some nanofluidic transistors a few weeks back,…
In my last post, I described a new process for reducing fluoropolymer build up during RIE. Unfortunately, the new process had substantially lower yields (half) than the process I was using before. In this post, I am detailing my attempts to make the MgF2 nanomembranes stronger to try and improve the yield of my current etching…
In our previous post I relate how our first experience with the membranes encountered some difficulties. These were mostly of two kinds: clogging or braking of the membrane and somewhat arbitrary sizing of the particles. We think we have fixed both. In our latest experiments we have used manually-extruded particles. These are obtained after the…