There was a paper years ago regarding an optical absorption CO2 sensor. They
utilized several cells, few had known CO2 concentration and one had the
sample. If I remember right they had poly heaters as IR light source.
They were subtracting the  sample cell reading from the reference cells
using some algorithm

Shay

-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of ABHIJITH.N
Sent: Wednesday, September 28, 2005 6:25 AM
To: General MEMS discussion
Subject: Re: [mems-talk] mems based CO2 sensor?


Hi Suresh
Generally mems based gas sensors are metal oxide sensos which show response
to reducing or oxidising gases.Unfortunately CO2 cannot be detected by such
sensors.So I think one method to do a CO2 sensor would be to use IR
absorption spectra.One should fabricate a tunable optical filter (ppl have
done that) and a IR detector with  on chip spectrum analysing circuitry
using mems technology.There may be other simpler solutions but i am unaware
of them.
abhijith