"Greenhouse Effect" is melting the Earth ice core every minute and creating dangerous icebergs. By knowing the exact concentration of CO2(Carbon Dioxide), we can do something to reduce the CO2 and to protect our Earth. Here is the Arduino-based CO2 sensor designed by DFRobot lovely engineer.
This is the first CO2 sensor in the Arduino market. The output voltage of the module falls as the concentration of the CO2 increases. The potentiometer onboard is designed to set the threshold of voltage. As long as the CO2 concentration is high enough (the voltage is lower than the threshold), a digital signal (ON/OFF) will be released.
To ease the difficulty of using this CO2 sensor, a Gravity Interface is adapted to allow plug&play. The Arduino IO expansion shield is the best match for this CO2 senor connecting to your Arduino microcontroller.
This is an electrochemical Arduino-based CO2 sensor, it is suitable for qualitative analysis. There are other Infrared CO2 sensors, which could make a quantitative analysis.