Advice for OD calibration range

Dear Pioreactor Team,

I have been testing the OD calibration of the Pioreactors for the last couple of months and I would like to take your advice on several questions to improve the outcome of the calibration.

  1. I am planning to run long experiments where the culture turbidity can reach an OD of 6-8. Hence, I tested to calibrate the capture OD measurements at the range of 0.02 - 6.3. However, for a certain OD range, the calibration plot was a horizontal line (as the picture below). Does this occur due to PD / LED limit?

  1. Another thing I realized is that, the choice of MAX OD value for the calibration has an influence on the lower OD measurements. For instance, Pioreactors which were calibrated with MAX OD = 6.3 showed higher variation in lower OD measurements compared to Pioreactors calibrated with MAX OD = 2.5 (picture below). The right OD value of the inoculum was supposed to be around 0.05, which was confirmed by using spectrophotometer. Hence, does this mean that, for capturing high OD values, one need to sacrifice precision in lower OD measurements or is there a way to have good precision in lower OD values while being able to calibrate for high OD range?

  1. Pioreactors calibrated with an MAX OD = 2.5 hits a measurement limit once the OD measurements reaches around the calibration limits (pictures below). Do you think one can avoid this measurement limit 1) by changing the plot fit from polynomial to linear 2) by disabling the calibration from the config.ini?

In advance, thank you for your help and time!

1 Like