Questions about the Oxygen Sensor (MIX8410)

I have an Oxygen Sensor (MIX8410), connected to the Seeduino 4.3 through a Base Shield. I am a little confused about how the code is working. When I connect the sensor, and run the code provided on the wiki page, on the Serial Monitor Vout is measured at 1,55V and the O2 reading is 16% (instead of 21% - the measurement is on open environment. If i change the Vout at this line

float Concentration = MeasuredVout * 0.21 / 2.0;

and instead of 2.0, i give it 1,55, the O2% is correct (21%). Should I leave the line intact, or change it, depending on the environment I intend to use the sensor (which is about 10% oxygen)?

Hi there,
So full scale is 25% , how do you calibrate it , Do you allow proper warm up also?
GL :slight_smile: PJ

What do you mean by full scale?
I calibrated it using a professional oxygen meter. I want to use the grove one on a range from 9% to 15% oxygen environment. If I leave the code line I mentioned as it is, the O2 reading, after 20 minutes of warm up is at approximately 16,26% O2 and the Vout it prints is at 1,55V. I am using 3,3 V as Vref…
If I set the output voltage variable at 1,55 the O2 is at 21%.

If I start decreasing the O2 level of the environment, at around 13%, I have to change the output voltage variable from 2.0 to 1.48 in order to read the correct O2 level, based on the reading of the professional instrument used to calibrate the Grove O2 sensor. Do I always need to change the output voltage variable, based on the range of O2 I am working?

Hi there, That’s a good question. I don’t know the answer for sure but , I would think the sensitivity would greater as well. The data sheet say’s it’s full-scale reading is 25% so being in the middle is a good thing, IMO. YES.
I have used PPM and even a PPT ,O2 and Moisture Analyzers, Meeco & CNC liquid based, frozen mirror type from Osaka japan. For the semiconductor industry Ultra Pure Gases required to make clean wafers and the least fall-out in the industry. Those instrument’s took DAYS to dry down to there LDL. Warm up is key. Zero is important as is the voltage range (taking into account any offset)
GL :slight_smile: PJ
Four generations of Analyzer carts, I went around the world installing and training folks up on these Bleeding edge of technology.

You are doing a kinda calibration. a Zero and Full-scale