Oxygen Sensor

Greetings,

I would like to measure the oxygen in the air of a room. What sensors are there that I can use?

I tried to find on the internet and only found Grove O² Gas Sensor. Are there others?

Thank you,
Pedro Oliveira

I have never had to buy a sensor for this.

There are spectra of air samples available freely. Here is one. Check page 5 and 6. I would reccomend maybe graphing the values to ensure you can pick a frequency not overlapped by other molecules.
http://irina.eas.gatech.edu/EAS8803_Fall2009/Lec6.pdf

Oxygen seems to have a "fairly" clear weak/broad peak around 6-7micrometers (w-b 650nm) in the thermal IR. Laser diodes are cheap in the 650nm range and there are plenty of photodiodes that are susceptible to that wavelength.

I have no idea if the sensitivity or the resolution of the photodiodes available will be able to give you the resolution you require, but dry air (you could pass a sample of the air through a desiccating agent in a tube?) should give a fairly responsive change in transmittance?

The absorption band usually used for oxygen sensing is around 760nm (13100cm^-1 in wavenumbers). You can google the spectrum. The lines at lower wavelengths are weaker and the laser around 760nm are also available at low prices.

Ah. Use this then. Did not know they were that cheap at 760nm!

Also, for a photodiode sensitive over that region, you could use a bandpass filter over the photodiode to get a little better filtering?

http://www.knightoptical.com/_public/documents/1372681785_760nmbandpassfilterinterferencestandardnirrange10nmfwhm760fib.pdf

This means you may be able to use a 760nm centred IR LED instead.

In the UK, these are about £2 each:
http://uk.mouser.com/ProductDetail/Plessey-Semiconductors/PLR3535AAS000/?qs=sGAEpiMZZMu4Prknbu83ywh%2bNcac0Y7%2bSdPgYG3n4eTI9PE%2F0foVDw%3D%3D

A 760nm laser would be the best of course...

Plan B:

4OXV CiTiceL®
Oxygen (O2) Gas Sensor (Battery)

Made in UK