Drunk Driving Detection System

This project is an alcohol-detection-based ignition lock system built for electric scooters, designed for deployment in public spaces where shared scooters are available for use. The goal is to prevent intoxicated individuals from operating electric scooters, reducing the risk of accidents caused by drunk driving.

How It Works

When a rider attempts to start the electric scooter, they are prompted to blow into the MQ-3 alcohol sensor module. The MQ-3 is a semiconductor gas sensor that detects ethanol vapor — its internal resistance drops in proportion to the alcohol concentration in the breath sample.

The sensor feeds its analog output to an Arduino microcontroller, which reads the voltage and compares it against a calibrated threshold corresponding to a safe blood alcohol concentration (BAC) level. If the reading stays below the threshold, the Arduino enables the ignition relay and the scooter starts normally. If alcohol is detected above the threshold, the relay remains open, the ignition is blocked, and the scooter does not start.

Components

  • Arduino Uno — microcontroller for sensor reading and relay control
  • MQ-3 Alcohol Sensor — detects ethanol in exhaled breath via resistance change
  • Relay Module — controls the scooter ignition circuit
  • Power supply — draws from scooter battery

Public Deployment Context

The system is intended for shared electric scooters in public areas — parks, campuses, tourist zones, or any location where rental scooters are available to the general public. Rather than relying on user honesty or manual checks, the hardware enforces sobriety at the point of ignition, making it a passive and automatic safety layer.

This approach addresses a real gap in micromobility safety: electric scooters are increasingly common in urban environments, yet few have built-in safeguards against intoxicated operation. Embedding this detection directly into the ignition circuit makes the safety check non-bypassable.

Outcome

The prototype successfully demonstrated real-time alcohol detection and ignition locking on an electric scooter platform. The MQ-3 sensor reliably triggered the lockout when alcohol was present in the breath sample, and the scooter started without issue when no alcohol was detected.