Hi BSTRobin, like you I'm interested in looking at gas mixtures in ambient air. When i worked I spent my time looking at the effect of different gases on both metal and organic semiconductor sensors. Normally it will take severa seconds to get anything like a stable reading, looking at a response after say 140 msecs will give some information about the sensor resistance as it heats up, it will not be an equilibrium gas reading. Looking at mixtures will complicate this as different gases will adsorb and react at different rates, so the sensor resistance will be the sum of the different gases adsorbed at that temperature. I've just bought the BME688 system in the hope of using multiple sensors at different temperatures to try to look at gas mixtures. I've worked with sensors set at 3 temps, which it is claimed detect different gases because of different sensitivities with temp, but looking at normalised data from large data sets I'm coming to the conclusion that tin oxide sensors are being affected more by humidity than gas effects, correlation of gas effects with temp, press and humidity show a marked correlation between humidity and gas effects. So I'm not sure whether or not this approach will be any better, but if I can find a way to programme the temp profiles I'll do what you appear to be suggesting, I don't hold out a lot of hope of success, but it will be interested when I can sort out how to program the temp and duration of a test. Hope you have some luck!
... View more