We were inspired by the Pip Boy from Fallout and the new keyless Tesla cars to build a "portable" (not at the moment) breathalyzer that locks your Tesla car, amongst other things (or any other car using a RESTful API to control its functions).
What it does
A user breathes into the MQ303 Ethanol measurement device to read changes in the acidity of the air, calculates the BAC and uses standard legal charts to determine whether one is able to drive. If not it locks the car using the available RESTful API for the vehicle.
How I built it
We built the items using the ARM mbed LPC11U24 which was handed out as swag during the event. The rest of the electronics were acquired from around the venue and a quick trip to a closeby Maplin to grab the missing breadboard.
Challenges I ran into
Finding the electronic components necessary, reading the output of the MQ303 sensor, inconsistent datasheets, researching relation between resistance and concentration.
Accomplishments that I'm proud of
What I learned
Lots about using electronic resistance in the air to read ethanol values and converting these to Ethanol PPM values.
What's next for DUI-Locker
Making the system portable and more reliable using an encasing, sending information over bluetooth instead of usb.