I do apologise for the late reply.
As I am the one running the experiment for the R&D I made a decision to put less strict condition on it. At least to have a first clue on what's going on.
Also because the stand-alone logger and sensor are massively expensive (we are speaking about 500+ pounds).
1) I dod not need anymore a "soft bag", so I probably will use something (with the same volume) but more handy, let's say a plastic airtight box?
2) I CAN now run a cable/wire from inside the sealed box to the outside and connect to an Arduino UNO to log the results.
I still need to make air tight the hole where I will run the cable though! But it should not be too difficult.
Now I will reply to some of you:
This device is bulky and expensive, but also precise, repeatable, and easy to interface with Arduino.
Yes and I found a Vernier shield that will allow a straightforward connection between this sensor and the Arduino UNO. Now I will need to understand HOW to log the date for example on a SD card???
We are around 300£ here.
Quick and dirty version:
Sensors, something like an R22, or one of the many clones (or an R17 if you want smaller), buffer the readings with an op-amp (you'll want to amp it up anyway, output in air @ 1 bar is ~11mv).
Assuming you're surrounded by air, you could send the readings using a bluetooth board, or if you prefer wifi, maybe do it with an ESP8266.
You might try googling arduino ccr controller, its been done a few times :)
This is a cheaper option: http://www.cambridge-sensotec.co.uk/shop/ad300/176-r17-van-oxygen-sensor.html
The thing is I will need to investigate and "play a bit" with the board and sensor and some tutorials in order to understand HOW to make it works. Of course, all this new knowledge will be an added value for my future projects... BUT it will need more time.
We are around perhaps 70-80£ total here.
You'll find most galvanic sensors are around £40-60. Typical life is ~18-24 months (you can get longer, despite what the literature says).
See previous quote :)
It depends on what range of O2 concentration you want to measure. 0-25% (normal atmosphere to oxygen depleted) is pretty easy and cheap. 0-100% (enriched atmosphere) is more expensive but should not be too hard to meet your requirements.
co2sensor.com, despite the name, has a good sensor for the 0-25% range.
Ideally 0-100% but I believe 0-25% will work as fine as well.
FYI, I could not reach your link.
OK guys so let's start from the new "rules" (less restrictions) of the project :)
And, obviously any more insights or suggestions will be really appreciated, just simply to say "don't do this if you are not expert because you will take 2 months to learn (I do not have 2 months :) ) etc.
Thanks a lot to everyone participating on this thread.