Issues with OD/temp measurements

[bgwong]

The signal increases up to a certain extent, and then it decreases after the culture gets too dense and starts to decrease in value.

Here is an older post that gives more information:

OD measurements with two photodiodes?

Summary I’m looking for some advice on how to properly do calibrations with two variables. Background I’m trying to integrate hardware configuration for OD measurements to improve the consistency and dynamic range of the sensors. I figured adding a different sensor at a different LED-diode offset would do the trick. I did a simple, rough experiment and collected measurements off of 90 degree and 135 degree offsets with increasing amount of milk (to approximate scattering from cells). Heres t…

[bgwong]

@anupama You have the boards for it but the sensor on there was incorrect. You would have to switch it out with a different photodiode than what you have for it to work well.

[bgwong]

One other note. The RAW values are inverted due to the design of the hardware. In other words, The higher the RAW value, the lower the signal (e.g. photodiode signal). I know its a bit confusing but its an important distinction.

[anupama]

Thanks for explaining that the drop in the OD values is because culture become too dense and it is hardware related. We were worried if it is because of something we did wrong during the calibration.