My name is Simoné and I work in a research facility on plant developmental biology. I use your Qwiic Scale card for a pressure probe, i.e. a device that can be used to measure hydrostatic pressure of plant cells (the so called turgor pressure). The measurement is done by physically piercing a cell by a thin oil-filled glass capillary. The capillary is connected to a chamber holding a piston, used to apply pressure to the oil, and a pressure transducer (in my casea Kulite XTL-123B-190M-17BARA, an absolute pressure transducer). Once the cell is pierced, if there is no leakage, the meniscus formed between the oil and the cell sap will move away from the capillary tip because of compression of different elements of the device (like oil, joints etc…) and the true turgor pressure is then measured when the meniscus is brought back (by using the piston) to its position before piercing (so close to the cell wall).
In my current configuration, after calibrating the pressure reading, I can read a maximum pressure of 6.2 Bars. If on some samples this pressure is above tugor pressure, in some other samples (like hypocotyles) the turgor can larger then 10 Bars, which means that I can’t get a measurement on those tissues.
In order to solve this issue, I tried to reduce the gain of the Qwiic Scale, from 128 to 64, using the following code line at the end of the Setup part:
myScale.setGain(NAU7802_GAIN_64);
If by using the default gain I get a reading of around 0.5 Bars, when I set it to 64, I get 0. I still see 0.0000…even plotting 32 characters. I thought the effect of modifying the gain would have been linear (so going from 128 to 64 would have led to a factor of 0.5) but maybe I got it wrong!
Could you please give me some help on this issue?
Thanks a lot in advance,
Simoné