I would like to add a pH sensor and a dissolved oxygen sensor to my smart sleeve. Has anyone tried this before? Does anyone have any insight in this matter?
If you’ve added a sensor to your smart sleeve before, please share your story, even if it is not one of the sensors mentioned above.
I’m currently working on developing oxygen (and other gas) sensing functionality in eVOLVER. The short answer is that it’s really hard to get DO and pH sensors to scale across many vials. The cheaper (~$200/channel) galvanic probes are bulkier and take up a lot of space in the vial lid, and the expensive (~$2000/channel) fluorescence-based probes (like Presens or Pyroscience) require proprietary optical sensing devices and are harder to scale and integrate with eVOLVER.
One approach we’re working on is measuring gas concentrations with a single off-vial sensor, taking gas efflux from individual vials, but of course this doesn’t help with pH. If you’re interested in measuring pH/DO on a single vial or small number of vials, it would probably be easiest to set it up with a separate arduino/SAMD21 and breadboard to record ADC voltage measurements from the probe and send them to a computer with a python script running a serial connection. If you do want to have a pH or DO probe in every vial, you might want to work off the spare “RS485_LIGHT” arduino, and modify that script to record ADC values (like RS485_TEMP), and work through the eVOLVER server code to broadcast that data to the DPU. Or, work with a probe set that has logging software that can work with multiple sensors, and just record data outside the eVOLVER framework.
Additional considerations: If you’re trying to seal the vial to control oxygen flow, you’re going to want O-rings around the probes and under the lid, and airtight ports for your influx and efflux. Also, with a probe constantly submerged, biofilm accumulation can potentially throw off your measurements.