Carbon dioxide sensor??

Hi, I'm working on a project that measures outdoor air quality. Wondering if anyone knows a CO2 sensor that's not too difficult to use with a microchip (bs2 or arduino)? or knows of any links to air quality projects (the ones on MAKE seem to be broken links..) thanks! Kiera

rbhamare3 years ago
H2O Sensors...
hey , can you tell mi about underground H2O(water) detection sensor...???
mark484306 years ago
The small electro-chemical sensors are great for home projects and very inexpensive (20 bucks) to purchase. Google "CO2 Figaro" to find them. The dual-beam infrared tend to be more stable, longer life, more expensive ($100+) and are the standard for CO2 detection in green building construction. Google "CO2 Senseair" to find these.
This is the only thing kieranof ever posted (nearly 2 years ago) - he's gone.

Yep, it's also more as two years after you responded, but I still get a lot of useful info here.
No problem. I noticed the question on a google search for CO2 sensors on another project. Since it came up on the first page, I figured others might be still be researching the same subject, so I thought I could add to the discussion. That is all. Mark
mark484304 years ago
Instructions for using Arduino with SenseAir CO2 Sensor:
martin08114 years ago
The company E+E Elektronik does also have some nice products for CO2 measurement. More information about the CO2 sensor module is on
bjornos5 years ago
Hello. have a look at SenseAir's modules they manufacture Infrared maintenance free sensors, with life expectancy of normally 15 years. The normally never require calibration
poop#15 years ago
hey there is this sensor that is dirt cheap and meant for the bs2 go to
VIRON8 years ago
"Limewater" is the name of a solution of Calcium Hydroxide that turns
from clear to milky when carbon dioxide is absorbed by it. This is rather
simple and if you can find a scientific chemical supplier then a small
bottle of Ca(OH)2 is plenty for making CO2 detectors. It may involve
detecting reflected light from the cloudy water using an LED and
a light detector (CdS cell, solar cell, phototransistor, etc.).

I'm guessing limewater is not a deadly poison but it IS a chemical and
deserves respect. After all, even H2O (water) "may cause burns, explode,
blindness, intoxication, inhalation maybe fatal, etc" to drown laughing see
DHMO (Water) hazardous chemical
Johenix VIRON7 years ago
You can safely drink weak lime water, in the past it was used as an anti acid and was sold as such by pharmacies. How about monitoring the electrical conductivity of the lime water. As calcium carbonate is formed conductive calcium ions will be removed from solution. Perhaps we could soak a piece of blotting paper in a mixture of lime water and glycerine (to retard water evaporation) and pass a smallelectric current between two electrodes.
lemonie VIRON8 years ago
You'd have to quantify airflow through your solution of limewater and the do a gravimetric analysis afterwards. End resrult for any method is : measuring CO2 concentration isn't easy on the cheap.
And for (your choice)'s sake stay well clear of dihydrogen monoxide eh?
lemonie8 years ago
Why do you want to measure carbon dioxide, this is not usually an air quality indicator? An infra-red spectrometer might be your best bet, carbon dioxide absorbs strongly at ~2400 wavenumbers. Building one may be a pain, but infra-red LED for a start?
VIRON lemonie8 years ago
Sure. An IR LED, a prism or diffraction grating ("clear rainbow plastic"), a phototransistor, milliammeter, ... etc To calibrate / tune it to that wavelength use an IR camera and ... most important ... don't forget to exhale! (or use a dry ice cube , or just a pinch of baking soda + a drop of vinegar, or a cuppa that sticky brown gooey carbonated liquid from Hamburger Hell)
lemonie VIRON8 years ago
More thought: You can use a tungsten bulb as your IR source, you'd need filters of course, but water and polystyrene would do. Double-beam is the norm, but tricky without advanced optics... As my original comment why does CO2 need to be measured?
VIRON lemonie8 years ago
Kiera should answer that. Perhaps it's a safer science project than measuring noxious pollution (CO). Perhaps it's for experimentally optimized biosphere or school space research. Recently there was a contest challenge to survive locked up in a safe. Some of us want to KNOW exactly what we are inhaling. Etc.
westfw8 years ago
kieranof (author) 8 years ago
thanks for the comments/methods. it's definitely helpful to get these responses. thanks again :)