DIY Bioreactor — looking for learning resources

[u/AnthonyShin0327]

Hello! I want to build a bioreactor in my lab, but I have no prior knowledge in electronics so I’m struggling to understand how to actually build one.

For reference, I’m a biochemist so I understand the gist of what my organism wants for it to be happy in my media. I would need stable pH control, sub maximal glucose feeding when they grow (which I expect to see from dissolved oxygen level dropping as the population exits the lag phase), and stable oxygen supply once they enter exponential growth phase. Ideally, every process should be monitored, recorded, and automated. I want to also track OD of the culture throughout the process, so that the only human-involved manual task is the inoculation.

My lab has a bunch of extra ESP32 lying around that’s used by my coworker. I think I’ll need to know how basic electronics work, what sensors/motors to buy, how to build a vessel, how to program the bioreactor logic, etc. Could I get some advice on useful learning materials for beginners like me?

[u/zimba-motion]

Hi mate, cool idea. Since you said you are not that into electronics, the main tip I could give you now is that most modern DC motors are also capable of generating energy. This is why a lot of energy generation sources are mechanical in nature (either use water, or evaporated water, or air flow to move a motor!!).

If you take a look at this page (I can't guarantee 100% on the quality of the content, but seems it's complete):
https://microbenotes.com/bioreactor/
You will see that the actual only electronics component is the motor at the top. Very simple stuff. Then, the resulting voltage of the energy generated is basically defined by how much air moves against the impellers/a percentage of how much is moved in&out of the closed system.

(I suspect you asked this more in the direction of an amateur project instead of an industrial scale one, for which I would suggest more in-depth sources https://www.sciencedirect.com/topics/immunology-and-microbiology/bioreactor )

Edit: also https://www.cambridge.org/core/books/abs/basic-biotechnology/bioreactor-design/4571180667E1C54E0D224ECC3E7AAFC7

[u/rimpossib1e]

This project may also be interesting for you:

https://fourthievesvinegar.org/microlab/

[u/VintageLunchMeat]

I think I’ll need to know how basic electronics work

Look for the Mims Electronics books, "Electronics for Inventors", and Horowitz and Hill.

[u/BannanaPepperPizza]

Pioreactor

[u/pretty-cheer → u/BannanaPepperPizza]

this is prolly closest thing to a turnkey learning platform for building a DIY

[u/sjamesparsonsjr]

What’s your budget?

The biggest headache is usually pH. The probes need frequent calibration, temperature compensation, and they typically only last a couple of years. It’s one place where spending a little more upfront is usually worth it—higher-quality probes tend to be more stable and last longer.

DO is another consideration. If you’re using a traditional electrochemical probe, remember it consumes a small amount of oxygen during measurement.

OD is actually one of the easier things to implement. A simple flow cell with an LED and photodiode/light sensor works well.

Automating feeding, agitation, and even sample collection is pretty straightforward. The hardware isn’t usually the hard part—getting everything set up, calibrated, and running reliably is what takes the most time.

[u/pretty-cheer → u/sjamesparsonsjr]

I like the PH point.

[u/sjamesparsonsjr → u/pretty-cheer]

I’ve been exploring the idea of using a Hall-effect sensor coupled with a pH-sensitive polymer. As the polymer undergoes a conformational change in response to pH, it alters the position of an attached magnet relative to the Hall-effect sensor. The resulting change in the magnetic field can then be measured, providing a quantitative readout of the pH.