The latest CO2 gas sensors utilize an infared light source, and detector to detect the concentration of carbon dioxide gas in air.
I created this shield for the Arduino Mega to investigate the feasibility of using the visible spectrum of light for gas detection.
The system will measure the amount of light absorbed at each wavelength. Different gasses may react uniquely to different wavelengths; creating a "absorption spectrum fingerprint". This data can be analyzed by a computer to measure the % concentration of any gas in air. (perhaps carbon dioxide, carbon monoxide, nitrogen, oxygen, hydrogen...)
The system is comprised of a light source containing 30 unique LEDs, each with a different wavelength between 400 and 900 nm.
On the other end of the system is a light sensor which measures the light intensity after traveling through a sample.
This method of spectroscopy is useful in many fields related to chemistry, biology and material science.
OpenEAS is a general purpose Arduino shield for emission-absorption spectroscopy.