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I am using an MQ3 sensor for alcohol detection but the sensing distance is short. Is there any alternative approach or solution to detect alcohol present in air from a longer distance?

For example, the drunken driver exhales ethanol vapours, the sensor placed at steering should detect the alcohol content. But MQ3 sensors cannot detect the ethanol vapours at that distance. Is there any solution to this?

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  • $\begingroup$ How do you control the air currents? wind ? Door opens etc? $\endgroup$ – Solar Mike Jul 31 '17 at 6:36
  • $\begingroup$ currently I am using only the sensor , I need solution to pull the air currents or person's exhaled air . $\endgroup$ – Karthik ziffer Jul 31 '17 at 6:40
  • $\begingroup$ So, if the person is standing in a windy street how are you going to get the sample? Why do you think the testers the police use have people blow directly into the device? $\endgroup$ – Solar Mike Jul 31 '17 at 6:41
  • $\begingroup$ I dont want to detect it in open space , detection should happen in small closed space like car driver's compartment , at 2 feet range . $\endgroup$ – Karthik ziffer Jul 31 '17 at 6:45
  • $\begingroup$ Then you should improve your question as, at the moment, it is not clear. $\endgroup$ – Solar Mike Jul 31 '17 at 6:47
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Assuming that following MQ3 Alcohol Gas Sensor is the sensor referenced in this question. Per the specification the detection range is 25-500 ppm of Alcohol. The sensitivity is

$$\frac{R_{o(in \ air)}}{R_{s(125ppm\ C_{2}H_{5}OH)}} \ \leq \ 5$$

Alternatively take a look at MEMS Alcohol Gas Sensor GM-302B (note the link is in Chinese, so please use translate) which has a detection range of 1-500 ppm of alcohol. Also the sensitivity is 1.2 to 50,

enter image description here

References:

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