Various tests have been performed on the alcohol sensor mq3. The device responds to the presence of alcohol in the hand sanitizers with an increase in output voltage. The response time is, however, very slow, and the source of the alcohol has to be no more than 1cm away. This was found by dispersing the sanitizer on the hands, and performing a “hand washing” motion for 5 seconds, and then placing the hand a distance on the ruler away from the device. The results for 1cm follow (using Google Docs Spreadsheet). The start/stop tags in the third column refer to when the hand was placed, and when the hand was taken away, respectively.
For all the summary plots, the first point on each line notates when the hand was placed by the sensor, the second, when it was removed.
The results from the same experiment, except with the distance increased to 2cm follow. Because no noticeable results were produced, the distance was not increased.
Experiments were also performed with the device taped onto the sanitizer container.
The first of these was performing a hand washing motion in front of the sensor (on the sanitizer container). Links to the raw data follows. The start/stop tags in the third column refer to when the hand was placed near the sensor, and washing motion was started to when it was stopped, and the hand was moved away. Although these tests did produce an increase in voltage, the delay between when the test was started to when this was observed was even longer than earlier experiments (with the ruler).
Because previous iterations with the hand just being placed near the sensor when it was placed at the end of a ruler produced results, this was tried when it was on the hand sanitizer. Data for these follows. Some tests show no increase in voltage, and others do with a long delay.
Test 1 Test 2 Test 3 Test 4 Test 5 Test 6
This device does not seem suitable for our purposes because of its long response time. I believe it is meant to be used as a Breathalyzer, in which case the alcohol content of the air is more concentrated and directed into the device.