The pocket breathalyzer is a small, compact device that provides the user with a simple, cheap way to drink alcohol responsibly. Individuals can carry them in their pocket and bring them to house parties, bars, or anywhere they may need to check their own, a friend, or stranger's alcohol level.
Step 1: Materials & Tools
To build your pocket breathalyzer, you will need:
1 Alcohol Gas Sensor - MQ-3
1 Adafruit Feather Bluefruit
1 Rechargeable Lithium Battery
1 Small Protoboard
Step 2: Building the Circuit
Assemble the circuit following the schematic above. You'll need to solder everything onto the protoboard before proceeding to the next step. Depending on the size of your board, you may also need to cut part of it for it to fit inside the casing.
Step 3: Adding the Code
Open Arduino and paste this code into a new file. You'll need to download the Neopixel library for the code to work. Following that, plug the Adafruit feather into your computer and upload the code onto the board.
Step 4: Creating the Case
The casing for the pocket breathalyzer is 3D printed. After downloading the 3dm file below, you can have it done at any 3d printing facility nearby. The results should resemble the image above.
Step 5: Putting Everything Together
By now, the finished circuit should be soldered onto the protoboard, the code uploaded onto the Adafruit Feather, and the breathalyzer casing printed. When all that is done, carefully place the circuit into the bottom half of the case, with the protoboard and alcohol sensor in the appropriate slots (as demonstrated in the pictures above). Make sure the LED is visible through the square opening in the centre before taping it in the place to the top half of the case. Connect the two halves and add the three screws, tight enough to secure the whole breathalyzer.
Step 6: Try It Out!
Your pocket breathalyzer should be fully assembled and ready to be tested! Try it by either holding a swab dipped in rubbing alcohol above the opening, or drinking alcohol yourself and breathing into the device. If the LED light turns red, that means it's working and your breathalyzer can be taken out and used whenever you need it.