The main difficulty with creating a simulation of the single channel dialysis chip is that the membrane is so very thin (20 nm). This is especially true when compared to its length of 10 mm but also when compared to the channel depth and permeate well (which in our case is actually a beaker of…
There is a reliability/handling issue with the single slot chips. 0.5 mm x 10 mm slots, 20 nm thick membranes with 40 nm SiN reinforcement. The membranes are easily packaged in an upper fluidic PDMS layer with inlet/outlets and two PDMS struts (on the membrane side to protect from accidental contact breakage.) The first test…
In order to rapidly test the entire setup for dialysis evaluation, including piezoelectric micro motor and recirculating fluid path, a means of quickly evaluating PDMS designs is needed. A mold was created with a multi-print technique in which printer toner is built up to sufficient height by over printing the same transparency. (see Fig. 1)…
The purpose of the fluidics in our hemodialysis system is to move the sample to and the retentate away from the membranes. The dialysate (permeate, filtrate) will be handled passively in the initial designs and therefore do not require fluidic manipulation. The parameters influencing the movement of the sample past the membranes include channel geometry…
I wanted to update everyone on the recent attempts at the formation of the a closed flow system by bonding PDMS to our membrane chips, using capillary tubing for the inlet and outlets. Last week when we tried to preform the UV Ozone bonding it was unsuccessful. I initially thought the bonding did not occur…
In continuation of the desalting work, I ran three additional controls: a SepCon with no slits (negative control) and direct addition of 4M NaCl producing final dilutions of 1:400 and 1:600 (these are the experimental final dilutions I have been working with). The results are shown below. I also calculated the flux for each condition….
This is just an update on the progress being made towards creating a closed flow cell by bonding PDMS to our membrane chips. For those who were not at the meeting on Tuesday we have successfully bonded PDMS to both glass cover slips as well as out membrane chips using the UV Ozone cleaner. Yesterday…
Yesterday afternoon I made a new batch of 10:1 (base : curing agent) PDMS and put it in the oven at 80C for two hours to allow it to cure faster (compared to the three days it takes at room temperature). Once the PDMS was cured Henry used the UV Ozone system to again try…
After posting my observed results from yesterday I came in today to find that one of the segment of the PDMS was strongly bound to the glass cover slip, so strong in fact that trying to remove it caused the cover slip to break. This result comes in response to the comment that Chris made…
I talked with Jim last Friday about a second possible dialysis system using PDMS bound to a glass cover slip. I made a batch of PDMS and let it cure at room temperature over the past few days. Jim had suggested I try bonding the PDMS to a glass cover slip using the UV/Ozone system…