I’d like to build a system to dose CO₂ into a Pioreactor cluster using a manifold and a row of cheap mini solenoid valves, one per vessel. The solenoids would sit outside the Pioreactors and connect via tubing to luer‑lock fittings, which are what actually plug into the Pioreactor ports (so the valves themselves don’t need to be autoclavable or physically attached to the device).
My idea is to drive all the solenoids from a single HAT or similar board, and then control them through a small plugin or UI extension to send timed or event‑based CO₂ pulses. I’ve seen that some people have already experimented with solenoids together with Pioreactor, so I know this is at least partially explored.
I’m mainly looking for feedback on the practicality of this setup (electrical design, pressure/flow considerations, and any obvious pitfalls) before I start prototyping. Any thoughts or experiences would be very welcome!
Instead of a separate PIO HAT, why not have each Pioreactor control its own solenoid by plugging it into a PWM channel?
I’ve tried the valves that you linked to, but the tubing popped off due to the pressure of the gas inside. I’m not sure how you would go about securing the tubing as the inlet/outlets are smooth and not barbed. Maybe zip ties?
One big issue we’ve had with solenoid valves and CO2 gas is backflow, causing liquid from the vial flowing up the tubing when the solenoid is turned off. Eli Silver from the Harris Lab at Brown University helped us figure out how to resolve it.
In short, you need a three-way solenoid that will vent the pressure when it’s turned off. We’re using this one from HPControl:
@Martin is working on a plugin for the solenoid that should be ready soon. We’re also experimenting with push-in fittings to use 6mm PE tubing (more compatible with CO2 gas).
So for my case, I am just looking for a system to purge oxygen both from the liquid and head-space before starting the experiment. In order to do so, I work with Luer check valves (unidirectional) from Darwin Microfluidics. (Video Attached), I guess that as I only need to proceed before inoculation… foam formation and potential overflow is something that I should not really worry about.
For me, it would be extremely helpful to automate this directly from the UI (including adding stirring to the purging process), as it would allow me to set up the system inside my chamber and proceed seamlessly. This would also enable more precise control over the purging process by defining specific time intervals and correlating them with temperature and gas dilution rates.
In other setups, I typically work with pressure buildup inside the vial, but I’ve found that gas tends to escape through the tubing, so I instead use a septum-style sealed lid.
I’m really looking forward to seeing the updates that come out of the project you mentioned! Please let me know if there’s anything I can help with.
