Discoloration – loose ends & ground up wafer
There were some ideas being thrown around a couple weeks ago about discoloration results. I tested a couple of them out last week. These experiments were with w615 pieces, in the 37C oven in serum-free DMEM. I tested if vacuum grease or nailpolish would cause discoloration, I repeated the membrane up vs. down experiments that Anant did, and then I ground up a part of w615 and added it to the well.
It looks like membrane up and membrane down discolored at about the same rates. A couple of Anant’s posts (post2) showed conflicting results with membrane up vs. membrane down discoloration, so it doesn’t seem like there is a consistent result with this test. Neither the vacuum grease nor the nailpolish caused discoloration any faster than control. I think if these substances caused discoloration, the chip would be discolored right under the grease or polish spots. Therefore, I don’t think we can blame grease or nailpolish for any of the results from the Sepcon format experiments.
Interestingly, it looks like the presence of lots of ground up wafer pieces slowed discoloration. If there is a catalytic effect amongst aSi, pnc-Si and SiO2, I would expect that ground up wafer would accelerate discoloration. Instead, it’s possible that a huge surface area increase from the ground up pieces decreased the discoloration rate of the chip sample.