OD calibration issues - signal maxed out?

Hi, I was wondering if anyone has run into an issue where it seems like the light detectors are being maxed out? I’m having trouble with our OD calibrations, and it the signal from the sensors stays relatively constant regardless of the OD of the solution.

Can you provide more details? Like what OD it says on the plate reader? What type of cells you have been using? What media type?

Also, can you tell me what OD you are reading from? OD135? OD90? Can you also send me your calibration curves?


We are using E. coli cells in M9 minimal medium.

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The curves generated from the OD_135 seem alright, but then if we use that calibration, the OD values don’t make sense, and using the same vials that we used for the calibration yields different ODs, some even being negative and some being NaN

We tried completely blocking any light by putting a paper towel in, and we still got the same value in the GUI

The OD 135 looks pretty good. Did you select the OD135 calibration file on the setup screen to use that calibration for the experient? If a calibration file was successfully generated, you should see the name pop up when clicking the button next to “OD:”. All calibration files you generated should be there. When you start the experiment, it will use whatever calibration file you have active.

Yes, I’ve tried loading that into the calibration, but we still got incorrect ODs with that calibration

We’ll reach out soon to help you out.