Configure sparging and electrolysis

1. On the Configuration page, check config.ini contains the following. The installer adds 4=relay and the [electropioreactor.config] section; channels 2 and 3 were set in Nutrient solution.

   [PWM]
   # map the PWM channels to externals.
   # hardware PWM are available on channels 1 & 3.
   1=stirring
   2=waste
   3=media
   4=relay
   5=heating
   
   [electropioreactor.config]
   electrolysis_power=2.5              ; LED D intensity (0-10 %, clamped at runtime)
   sparge_duration_seconds=10.0        ; solenoid open time per cycle (s)
   sparge_interval_minutes=60.0        ; cycle frequency (min)
   od_pause_after_sparge_seconds=5.0   ; OD settle window after sparge ends (s)

2. Open electroPioreactor from Activities on the Manage screen.

3. Set a test spargeBubbling gas through the culture. Here, CO₂ from the cylinder flows down the anode on a timer set in the electroPioreactor job. in the job’s Settings panel: interval 1 minute, duration 1 second.

4. Listen for the solenoidAn electric valve on PWM channel 4 that opens to sparge. It must be 3-way venting (3/2), so the line vents when it closes. clicking open at each sparge.

5. Open the needle valveA fine-adjustment valve on the solenoid's front port. It sets how fast CO₂ flows; turn clockwise to close. while watching the vial, until the bubbling looks right.

6. Set your working sparge interval and duration in the job’s Settings panel. The MEP runs 3 seconds every hour.

Notes

• All four parameters are editable live from Settings. od_pause_after_sparge_seconds applies from the next sparge.
• ElectrolysisSplitting water with an electric current: hydrogen at the cathode, oxygen at the anode. It supplies the hydrogen the HOB grow on. power stays clamped to 10% at runtime to protect the electrodes.

Check your work

1. During the test spargeBubbling gas through the culture. Here, CO₂ from the cylinder flows down the anode on a timer set in the electroPioreactor job., what do you hear and see each minute?

   • A click, but no bubbles entering the vial
   • No click, and no bubbles entering the vial
   • A click, then bubbles entering the vial
   Show the answer

   Answer: A click, then bubbles entering the vial

   • If you see A click, but no bubbles entering the vial: Check the cylinder is open (pin screw fully down) and the needle valveA fine-adjustment valve on the solenoid's front port. It sets how fast CO₂ flows; turn clockwise to close. is not closed.
   • If you see No click, and no bubbles entering the vial: Check the solenoidAn electric valve on PWM channel 4 that opens to sparge. It must be 3-way venting (3/2), so the line vents when it closes. lead is in PWMOne of the HAT's five switched power outputs. In this build: 1 stirring, 2 media pump, 3 waste (product) pump, 4 CO₂ solenoid (relay), 5 heating. 4, 4=relay is in config.ini, and the 12 V supply is connected.

2. When the solenoidAn electric valve on PWM channel 4 that opens to sparge. It must be 3-way venting (3/2), so the line vents when it closes. clicks shut, what does the bubbling do?

   • Carries on after the click
   • Stops with the click
   Show the answer

   Answer: Stops with the click

   • If you see Carries on after the click: Check the solenoid overrideThe dial on the front of the solenoid. 0 is normal (closed without power); 1 holds the valve open. is at 0.

≈ 0.02 g CO₂e per view