Midterm Project – Breathalyzer

For my midterm project I decided to make a “breathalyzer”, called the Drunkometer. The first few days of planning I considered ideas for my project and after some researching, a breathalyzer called out to me as the most sensible and entertaining concept to create in such a short time frame.

I ordered an MQ-3 sensor from Sparkfun on Tuesday, March 22, but after several days of waiting for it to arrive I went to Tinkersphere and bought an MQ2 Gas Sensor, which detects propane, methane, butane, and smoke as well as alcohol levels. The scope of the MQ-2 in detecting alcohol concentration is 100-2000 ppm (0.01-0.2%).

After getting the alcohol sensor, I began to set up my breadboard. It consists of 10 simple LEDs which light up according to the analog input obtained from the MQ2, which the user breathes into (see progress documentation for detailed circuit). I didn’t have any problems with this as the circuit is pretty simple, and the MQ2 I bought was built for the Arduino/Raspberry Pi so I did not have to do any additional wiring/soldering.

I originally wanted to make it into a game, in which two people blew into two different breathalyzers and competed for the higher score, but realized this was impossible without two Arduinos. So, I scratched that idea and decided to make it a competition in which you try to get to the 10/10 LED spot (the highest possible value). If you get to the 10th spot, a congratulations message appears.

After making the box, I realized that it was difficult to see the LEDs as you blow into the mouth tube, as the height of the box was too tall. Thus, I decided to implement Processing to visualize the input data on my computer screen for the user. This took some time to implement, both design and programming-wise as I’m unfamiliar with Processing. However, I am pleased with the final product!

The idea for this was obtained from Daniel Andrade.

Arduino Code:

Processing Code:

Progress Documentation:


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