Rotting food detector

Hi there,

I'm new on the maker scene and to date I've only really played around with some LEDs using a raspberry pi. I am planning on picking up an arduino for my next build though and was hoping I could get some advice on how best to proceed.

I want to have several sensors for different types of gasses, specifically: methane, Co2 and Ethylene in my fridge reporting back to the arduino so I can get a notification of some type that I should clean up my leftovers.

My questions:

I've read that any catalytic sensor should work if it's properly calibrated, if this is true, how would I calibrate it? Are there any guides on setting the threshold for these sensors?

Are there any specific types of sensors you would recommend?

Has anyone done this or something like this before and if so what advice would you offer?

I find it hard to imagine that any detector could beat my nose in this sort of application, but some people lack a good sense of smell and might benefit.

Calibration would probably be difficult.

Google "callibrating gas sensors". Basically, buy a canister of the gas you need and use it in an enclosure with the sensor. Alternatively, send the sensor to a lab to get it calibrated.

My older son cannot smell most things. Used to make skunk study skins for a lab while he was in college. they made him stop. Now he has a wife that tests things for him.


I would take a more practical view of calibrating and set up the sensor(s)- you probably just want a VOC sensor- in a fridge with only the food item you want to test for off-ness and workout the level of each gas you can test for as the food deteriorates.

You are basically doing a rough calibration to the state of the food rather than the actual concentration of a particular gas, each food type will release different gases and at different levels as they deteriorate.

ie. on arduino:

0v = fresh
1v = OK
2V = risky
3V = chuck it
4V = you chuck
5v = destroy fridge

something like that

then you know for example that the pizza is no good when the VOC sensor is at a particular level.

I don't think having an accurate calibrated reading for methane, CO2 etc. in a fridge with a mix of foods will tell you if your pizza has gone off.

If you have fruit and vege in the fridge at all then even at low temps they will continue to respire releasing CO2 and in some cases ethylene even if they are perfectly fresh, particularly if you've just put them in warm.

Good luck,

sounds like a meth lab in the design phase :grin: