Previous posts: Anodic Bonding Theory, Anodic Bonding Setup   I had originally hoped there would be enough residual impurity in the oxide layer to create a direct bond with Vincent’s chips. This was a foolish hope. Pyrex is at least 4-5% doping and standard p-doped silicon wafers are 5-6 orders of magnitude less than that, with…

In my previous post, I mentioned the effects of varying electrode geometry on the TEER value measured from COMSOL simulations. I had assumed that membrane has uniform porosity i.e. 100% active area, which is the case with the commercial polymer membranes. pncSi and analogs, however, have only a a finite section of its total area…

Previous Posts Anodic Bonding Theory, Anodic Bonding at RIT I’ve put together an anodic bonder setup here at the U of R and will be moving it inside the cleanroom shortly.     I tried a couple of known combinations to see if the bonder was working properly. The general principle is to liberate sodium ions…

Key Ideas I took a wafer with ~400 chips of varying square window sizes, ran my MgF2 process, and recorded the pressures it took to burst them. Overall yield was about 20%, most of them smaller windows. I was expecting ~50% based on my previous work. Variation in the etch step destroyed the yield. MgF2 nanomembranes…

Background: This is a follow up to the blog that Jim wrote on the basics of TEER measurement. This is the link to my old blog, which also describes the theory and some other preliminary data about TEER measurements. The resistance (R) of a wire is the resistivity (ρ) times its length (L) divided the cross sectional area (A) of…

Transendothelial electrical resistance measurements are expressed in the units . Where the measured resistance is multiplied by the area of the membrane to enable a comparison between measurements in different systems. We have often wondered why, but the reasoning for this normalization is straightforward. Consider the simplified ‘transwell’ geometry where a membrane separates two compartments…

Last fall we decided to try to integrate a filter immediately upstream of Vincent Tabard-Cossa’s nanopore DNA sensors. The idea is to assemble back-to-back a NPN membrane a standard nitride membrane used in Vincent’s nanopore fabrication system an oxide spacer. Currently the lifetime of these sensors/sequencers is limited by clogging events. The purpose of our…

As part of my thesis work, I hope to create modular pumps and flow sensors using silicon nanomembrane technology. Devices that could generate/detect microliter and nanoliter scale flows would decrease the overall size of microsystems, replacing larger micropumps (pneumatic PDMS, Chip-sized peristaltic pumps) and costly detection schemes (laser reflectometry). These smaller devices would enable efficient scaling of ‘culture…

In a previous post (linked here), I discussed a naïve way to incorporate concentration polarization into our theoretical model of the sieving of charged nanoparticles. Essentially, I considered the particles to be uncharged point particles that were subject to a force pushing them toward a surface (fluid velocity) and a force pushing them away from…