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This nifty little sensor is essentially an electronic nose or scent sniffer of sorts! Using a tin dioxide semiconductor material, this gas detector is able to detect organic solvents like alcohol among other things. Accoring to the datasheet, the TGS 822 is also capable of detecting gases made up of Methane, Carbon monoxide , Isobutane,N-Hexane, Benzene, Ethanol, and Acetone. Sounds like some interesting experimentation potential! The sensors resistive conductivity is relatively stable and,low in clean air, however when it senses one of it's target gases, it's conductivity goes up and there is a lower resistance through the unit. I built a quick test mock up with one and was able to detect the fumes from a mouthwash bottle when I took the lid off.

If you do a google search on the TGS 822 you can find lots of info and applications that people have thought up for the unit. I ran across a proposal for a domestic robot student project where they were going to use an 822 in the robot as an air hazards sensor. A datasheet for the device can be found at http://www.tashika.co.jp/PDFs/822.pdf among other places.

The price listed is for 1 NEW sensor.

These are new and fresh July 2006 units. Normally these cost from $18-$24 each if you can find them as I understand.

I was able to purchase these at a much more reasonable price and I am happy to able to pass the savings on to you.

International buyers are responsible for paying any import duties or other fees.

On Apr-21-07 at 21:22:40 PDT, seller added the following information: