I would like to build a electronic flatulence (fart) detector. I was thinking of methane because detectors are readily available, but I read http://en.wikipedia.org/wiki/Flatulence and it says:
However, not all humans produce flatus that contains methane. For example, in one study of the feces of nine adults, only five of the samples contained archaea capable of producing methane.
Oxygen, nitrogen, carbon dioxide are listed but I think they would be too common in normal air. That seems to leave:
- Hydrogen sulfide
- Methyl mercaptan
- Dimethyl sulfide
- Dimethyl trisulfide
Does anyone know if practical sensors are available that detect those gases or have other ideas? I think somewhere around the $20 or less mark would be good, so I wasn't really seeking a full professional solution like gas chromatography that may normally be used.
The application is for under office type chairs, so maybe heat detection could be used although I'm not sure it would be posible to tell the difference between the desired event and someone just sitting down on a cold chair, although maybe a pressure sensor could be used along with some filtering to not trigger until the temperature had stabilized a bit.