Development of a breathalyzer for car drivers

This work presents the development of a breathalyzer to be used inside a car. The breathalyzer constantly monitors the alcohol level in the ambient into a car, which is produced by the breath of the driver, principally. The breathalyzer uses an alcohol sensor MQ-3, a closed-normally electromagnetic relay to obstruct the ignition of the car, a global position system (GPS) module, a global system for mobile communications (GSM) module and a PIC18F25K50 microcontroller. The GPS module is used to know the position coordinates of the car whereas the GSM module is used to send a message to the security department of the place where is the parked car. The alcohol sensor, the electromagnetic relay and the two modules are controlled by the microcontroller. The proposed system was implemented and evaluated on five vehicles and tested with different alcohol levels ingested by the driver, showing a good performance in all cases.