Idea Proposal: Spoiled Food Detector

Hi Becky!

I haven’t fully fleshed out the idea yet, but I want to make a little shelf attachment for my fridge door, that can read if my vegetables are still edible.

I’ve been looking at a combination of pH sensors and ethylene sensors (rather unsuccessfully).

The pH sensor is quite expensive (, so I will look at making my own, following these instructions:

The ethylene sensor seems to be rather expensive/inaccessible as well:

So now I’m looking at this methane sensor:, as decaying food will also emit methane.


Sketch of vegetable freshness monitor, using pH sensor:

proposal-sketches-01The box would sit inside a shelf in my fridge door. The sensor would read the pH level of the water that the leafy green vegetables are sitting in (+ other veggies that sit in water), and translate it to a freshness level out of four bars: the fewer bars that are lit up, the less fresh the veggie is!





I was considering that the methane sensor wouldn’t make a lot of sense in combination with veggies, but perhaps I could translate it to work with spoiled meat:


So the idea is generally the same (in the sketch I am playing with the idea of red-yellow-green lights instead of bars), except that the meat sits in separate, closed compartments such that the air can saturate with methane.



I will update this post throughout the day with more details as I come across them—just wanted to make sure that I got it up on time!