Hi , can anyone tell me if the MQ series gas sensor care make the difference between different gases applied to them? As far as I can see they detect the gas/alcohol/smoke but can't make the difference.
The MQ sensors are wired up to provide an analog input, which tells you (after calibration) the concentration of gas it is detecting. But it has no idea which gases contributed to that reading. Worse, the sensor may be intended to detect a particular gas or gases, but it may also be influenced by others in addition to those it is designed for.
Write up a y= eqn for each gas / MQ sensor... use polynomials... now when you see CO reading around the same value on 3+ different sensors, you confirm that CO is affecting the Rs/Ro ratio.
You are correct! Get a sensor for each gas you want to test for. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil
Each type of MQ sensor is sensitive to several gases and can generally be used to tell if something in the mixture has changed, but not what has changed.
Several people have used an assembly of MQ sensors to make an electronic nose, but the best of those articles is currently off line. This electronic nose project uses a group of four different sensors from another manufacturer.