pH probes / monitoring

Has anyone connected a pH probe to their Pioreactor?

Raspberry Pi compatible pH boards seem to be available from Atlas Scientific, Anyleaf, Homelab-pH, DF Robot and others. The Atlas Scientific seems to be mentioned most in my brief googling.

I guess integrating one of these may be a step harder than the average plug-in, as a calibration interface would be required.

nanocastro on the GOSH Forum has confirmed that IO Rodeo’s pH FeatherWing is fully open source, as are their two pHMetros. Assuming we can get the same accuracy out of these and a standard probe as we can with one of the closed source options above (at least I couldn’t see evidence that the 4 linked in my earlier post are open) I’d be more inclined to buy one of them first.

Since it’s open, there appears to be good documentation in English and there are hardware calibration buttons that I assume may remove potential plug-in complexity, I’ll order a pH FeatherWing, unless anyone pipes up soon to say they’ve already had success with another route.

Do you think we would actually need the Adafruit Feather for it, or could we have it all running on the Pioreactor’s Raspberry Pi? I’ll ask Jo & William on the GOSH forum too, since they appear to be its creators…

I haven’t researched much about what pH probes will work with the Pioreactor. Mostly I’ve said to others: “pH probes are too large to fit into the vial”, which is mostly true, but there do (1) . exist (2) micro probes of 6-8mm diameter that would fit.

Also note that I am assuming the use of the Vial Cap A design, which has a large port (g1/8 threaded, 8.6mm diameter) for additional sensors.

Finding an open-source pH probe that could fit this size may be the biggest challenge. Calibration routines, jobs, and charts can be created pretty easily with the software.

You could re-design the cap to accommodate a large probe, but that’s additional design work!

I haven’t actually found any Open Source pH probes, and I don’t imagine I will as I assume the probes take so much precision engineering that the community would struggle to build them anyway.

I am however now in discussion with the makers of the pH FeatherWing which is a board with a standard BNC connector that should accept the majority of commercially available probes, including the 6mm Cole Palmer one that I found via your 2nd link.

Hi Martin

Did you find a good solution for a pH probe?
We are looking into that as well. What did you test and what solution did you go with in the end?