Hemodialysis chips are not surviving the priming process and the 4 hour dialysis treatment. We want to verify that the membranes are being weakened and also to determine if coating with oxide will ameliorate the problem. Using single slot chips from wafer 1153 I performed burst pressure tests on three groups of chips. 1. Bare chips…
We have wondered if we can skip anodic bonding and bond the chips using our UV ozone process. There are pros and cons to this approach, mainly that the setup and procedure is easy, but the contact and alignment is difficult. So I gave it a try. Here are a few SEMs of ozone bonded…
This is an addendum to the results I posted in my previous blog. I am trying to simulate cell growth on a transwell device and perform TEER measurements using a small chopstick electrode pair configuration. I modeled transwell membrane with different membrane areas, and observed the effect of cell growth on TEER values. TEER values,…
In my previous posts so far, I performed simulations to understand the behavior of TEER variation upon changes in electrode and membrane configuration. None of those models addresses the effects of cell growth on the TEER values. In real experiments, people measure the TEER of system before adding the cells (background TEER), and then monitor…
In an effort to better understand and check Karl’s model of sieving, I’ve built a significantly simpler version. The goal is to investigate the potential benefits of thinner membranes in dead-end filtration and separations. In my model 1 ml of water is displaced from the top bucket to an originally empty bottom bucket with a…
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…