I recently tested the burst pressures of samples from W510, 511, and 513. None of the membranes are pinhole free. Silicon thickness varies (15 nm, 10 nm, 20 nm). See Dave’s post for complete fabrication information.
W513 has noticeably higher burst pressures compared to W510 and 511. Overall W510 is in the worse shape overall, having the most pinholes and few intact membranes. W513 is in the best condition of the three.
Chris gave me a few wafers to look at with AFM – an oxide sputtered in the recently cleaned chamber and VA Semiconductor wafers cleaned with “Normal Power” or “Full Power” Megasonics. I employed a couple of new “tricks” to help with the imaging this time. All of these scans were taken almost entirely in…
A little while back I posted a design for a capture device that would (nominally) work for dialysis on real patients. Due to strict requirements to avoid clotting, the design included a lot of curves and nuanced structures that would be no problem for a lithographical or molding method, but which are a step too…
From my last blog post, was talked about designing an assay whereby the NPN filter would exclude DNA-conjugated gold nanoparticles while allowing short DNA to pass. Since then, I (with the help of my colleague Dan Tassier) have been wrestling with gold nanoparticles to find conditions in which the nanoparticles were stable, while also allowing…
SiMPore has been collaborating with the Infotonics Center to scale our SepCon production to a 6-inch wafer. The wafers are patterned and deposited at their facility and then brought back to UR where we anneal and etch. This week, we etched several wafers and the initial results look promising. The big news is that we…
Following up on our previous work with SiN-NP with varied RIE times, Sarah and I measured permeability and permeance using a new measuring system better suited to the higher permeance and permeability we expect with the larger pores and higher porosity. Using the pressure regulator pictured above, we can set pressures of 3 psi and above…
I tested all the microbeads that the Gaborski and Lapizco-Encinas labs own. The results are summarized below. The sizes ranged from 50 nm to 2 µm. I mixed them to concentrations of 0.2 g/L for all bead less than 1 µm and 1.0 g/L for all 1 µm or greater. Interestingly, the scans look rather…
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I guess this is the trend we expected to see. Keep in mind these three wafers were etched with the stainless cell that leeched iron spindles so that could be weakening the membranes…
The McGrath lab now has wafer 504 and 509 in their possession. Could someone pressure test these? Check with Jess/Tom before you start popping membranes out, though. These were etched in the new “old” etch cell.
It may also be worth trying various annealing treatments to try and reduce stress prior to pressure testing them. Maybe we could get some additional strength out of them..
I’m also curious about 504, since the edge does not look that great. We’ve got to get a better etch working soon…