Better protection for the electronic components when using salt water

After the last run we noticed a noticeable salt buildup of salt on the outside of one of the sleeves. I don’t think it was a major leak and everything seems to be working ok, but maybe there should be an option of a more waterproof housing. From my experience - salt water corrodes everything pretty rapidly (especially electronics).



It’s a bit concerning that there was some salt crystals in the sleeve. That probably means there was some overflow going on. With salt water, especially when dilution events aren’t very frequent, I am fearful that there might be salt crystals that build up the fluidic lines, causing the blockage for flow to/from the peristaltic pumps. This is especially critical for the efflux lines, since a blockage there would cause over flow.

@bgwong I wouldn’t be too worried about salt build up in the lines - we haven’t really saw it in the other growth systems we used (and this is the only evolver vial that we saw this happen). I think a more probable explanation is that it could be an accidental spill during the set-up etc. But still it would be nice to have electronic components a little bit more protected.

I’ll post here any spills that we observe.

@bgwong have you looked at consistency for overflow patterns? It appears this leaked out through the heating resistor screw port, but I might have expected it to leak out via the LED ports at the bottom. Are there differences based on the volume/location of the overflow? Or cap design (i.e. wide nylon vs old style green caps)?

If overflows are pretty consistent, maybe having a channel in the acrylic “floor” could help direct flow away from the electronics. If they are very inconsistent, maybe we should look into waterproofing sprays for certain components that are very exposed (i.e. heaters, LEDs). In my experience, the thermistor is the most sensitive to overflow, but I’m not sure how best to protect it.

The nylon caps are wider and help center the vial so it helps consistently align the vessel with the OD sensors. Since they are wider, anything the overflows typically just flows off the side, instead of flowing to the bottom of the LED ports. I’ve started to design some “vial shields” that help manage flow and protect some more of the electronics so it drops onto the platform and gets drained away.


I haven’t fully tested them yet but if anyone is interested in helping out with testing this, or designing a better system please let me know. I can share some thoughts on the designs. The solidworks file is here.