Our company manufactures air pollution analyzers both for ambient and
smoke stack monitoring applications.  We recently saw a CO2 sensor
that was offered to our company as an OEM part.  The device analyzes
for CO2 by measuring the IR absorption at 4.7 microns.  The device
monochromator was a tunable interference filter made by silicon micro
machining.  To do a measurement, a variable voltage was applied to
electrostatic pads on the structure, thus changing the separation of 2
closely spaced membranes which formed a resonant optical cavity.  This
would tune the filter to the CO2 absorption band, then an absorption
free wavelength nearby.

The complete working unit with calibrated and linearized LCD readout was
$595.00.

We were immediately interested in applying this technology to other
gasses.  Unfortunately, the manufacturer of the sensor is in Finland,
and is commercializing the process from a university research
environment.  They were not free to discuss any other applications.

Are you aware of any research groups or US companies that makes similar
devices?  We are interested in:

1) sensors without the full support electronics and readouts

2) sensors for gases other than CO2

If so please email me at ehoopes@advpol.com or voice telephone
619-657-9800.

Thank You,

Ed Hoopes
Advanced Pollution Instrumentation, Inc.
San Diego, Calif.