I made a breathalyzer using a MiCS-5524 gas sensor. I would like to calibrate it so it can be close to accurate. e2v technologies — MiCS Application Note 4, Using MiCS Sensors for Alcohol Detection (PDF) shows a method of heating an alcohol/water solution and testing the air that has been bubbled through the mixture.

If I was to heat a liter of alcohol/water solution to 37 °C, what ratio of alcohol to water would I need to make the air have 10 ppm of alcohol? I don't have much experience with chemistry so please keep that in mind when you explain the solution.

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    $\begingroup$ Now this is a case where experimenting on humans does not sound inhumane. Why not use your body as a test input? $\endgroup$ Oct 5, 2022 at 5:39
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    $\begingroup$ @IvanNeretin Human bodies are difficult to be adjusted to produce breath with 10 ppm of ethanol. :-) Unless evaluated side by side by the DIY and commercial tester. Then the particular ethanol content is not important. $\endgroup$
    – Poutnik
    Oct 5, 2022 at 7:25
  • $\begingroup$ I've done that already to see if it detects alcohol on my breath but its still hard to calculate a fairly precise ppm by just drinking some booze and blowing after a half hour. I was hoping to get a more precise read out so it'll work on persons of different heights and weights. $\endgroup$
    – Bill2k
    Oct 7, 2022 at 3:12


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