How To Smell Pollutants

Step 4 Test Your Newfound Sense of Smell

With everything connected, you're ready to hook the arduino up to your computer, fire up the arduino environment, and start reading values. Don't forget (like I initially did:)) to hit the 'monitor serial input' button in the arduino software.

You'll then begin to see values scrolling in the black space at the bottom of the arduino program. These values are the resistance, in ohms, being read from the circuit.

To test, blow slowly for at least a few seconds over the top of the sensor. The numbers on the screen should change. Also try holding the sensor over a high-concentration chemical that it should detect: my value jumped quite a bit doing this.

With ~4 days burn-in and ambient temperature of 63F, the values I read in my house were (which is reasonably free of chemical use):
-sitting in the open air, after sensor warms up for ~1 minute: 52
-breathing slowly over the sensor for several seconds: 73
-holding sensor directly over an open bottle of grain alcohol: 235