Steve G put a gas sensor in his K-9 robot.

Here is the discussion thread for the sensor: https://synthiam.com/Community/Questions/6342&page=2

And his project showcase where he describes the final configuration including discussion of the sensor (begins on page 4 I believe): https://synthiam.com/Community/Questions/6837

(fyi: The search engine here is not the best for searching things like this. It found all 1400+ threads with the word sensor and where gas was part of a word, but the site is indexed by Google. I did know that I was looking for it which helps, but this is the search I used in google to find the specific threads: http://lmgtfy.com/?q=site%3Ahttp%3A%2F%2Fwww.ez-robot.com%2FCommunity%2FForum%2F+%22gas+sensor%22 (don't be insulted by my use of "let me google that for you". This forum also interprets some characters as smilies or links that aren't, so the search string would not render correctly. I was not telling you to search before asking a question).

Alan

Thanks, @thetechguru

:P :P

Of course, I have done my search in ez-robot forum before I did this post. However, I did not find valuable information on the first two pages returned. That's why I start a new discussion and make my question public.

Thanks for sharing your method of searching. That really helps. :D