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I have a cigar lounge with a ventilation system, I would like to detect the "level" of cigar or cigarette smoke in the room. But I am not sure what sensor to go for, since these smokes contains a lot of different substances and I really want to measure the "smoke-level".

I have been looking for cigarette smoke detectors/sensors online but all I can find is detection systems with alarm output. I want to monitor the levels, to determine e.g. if it's rising or declining.

Any suggestions for what kind of sensor I could use?

Update: After doing some experiments, I ended up with a solution that works pretty good. I am using an MQ-2 sensor, which I am reading with an Arduino. I calculate the mean and standard deviation of the last 5 minutes, and compare it with the mean from the last three seconds. If there is an increase above 3 sigma, lasting for a couple of seconds, the "smoke" alarm flashes.

It also triggers on a couple of other things; like farting and using compressed air in a can.

Thomas Jensen
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I'm not entirely sure if this will be useful in your situation - but the way your typical smoke detector works is by measuring the radioactive decay, apparently Americum is at least used in some of them.

But I just learned something new (thanks, Wikipedia!) - apparently some smoke detectors use optical sensors!

So you should be able to do something similar in your lounge. It may take several sensors and combine their inputs. Obviously you'll have to deal with the fact that the smoke distribution probably isn't initially uniform. Potentially you could add an extractor to your room (not sure if that's desirable as I don't smoke) and measure the smoke levels there.

Not sure if there are any pre-built solutions, but perhaps you could gut several optical smoke alarms for their sensors.

Wayne Werner
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An article about this just popped up in my Feedly today!

A chemistry professor at Dartmouth developed a sensor called FreshAir that can detect Nicotine and Marijuana smoke and log each instance. I'm not sure if it can record "how much" smoke is present, though.

From the article I read, the sensor can be managed via Android over Bluetooth or over WiFi, thought it doesn't look like it'll be available until next year.

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The smoke detectors I know are all binary (smoke/no smoke).

Maybe you can detect it indirect measuring the CO2 concentration.

Unfortunately I know only one product Sensoair (IT monitors CO2 and VOC (volatile organic compounds)) but I'm searching for others: Are there different z-wave CO2 sensors?

smartmeta
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You can try several approaches:

  1. Disassemble an americium smoke detector and reverse engineer schematics. I've tried it once, inside was an ionization chamber and unmarked IC, most likely MC14468 clone. It had "guard" outputs that are connected to an output of the internal opamp that repeats voltage from the chamber. I think it can provide several mA, so you can connect it to a microcontroller's ADC or perhaps to Raspberry Pi's analog input. This method is relatively sensitive, but reaction is perceptable only when smell is already quite strong. It also relies on presence of guard outputs on IC, which may or may not be the case for concrete detector model,
  2. Disassemble an optical fire alarm. In worst case you'll have to reuse chamber, LED and photodiode, drive LED yourself and measure photodiode output. An uC paired with an opapm would be probably enough. It should be possible to construct the chamber using black paper, but I failed to get good results, I think due to lack of lens,
  3. Use a metal oxide gas sensor, e. g. TGS2600. It reacts to CO, H2 and several other gasses. In my experience it does detect smoke, but sensitivity and selectivity is rather low.

I'd advice not to bother with CO2 detectors, breathing releases far more CO2 than burning cigarette. I've actually tried with TGS4161, results are as expected.

Edit: restyled information as answer.

Alexander Morozov
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