IOT Based Alcohol Detector and Engine Lock system using Arduino

This project aims to design an IoT-based alcohol detection system integrated with an engine lock mechanism using an Arduino microcontroller. The system uses an MQ-3 gas sensor to detect alcohol presence in the driver’s breath. If alcohol is detected beyond a preset threshold, the system activates a relay to lock the engine, preventing the vehicle from starting.

An ESP8266 Wi-Fi module is used to send real-time alerts to a cloud server or mobile app, enabling remote monitoring. The solution enhances vehicle safety by ensuring that only sober individuals can operate the vehicle, helping reduce accidents due to drunk driving.

This smart system is cost-effective, easy to implement, and ideal for personal cars, commercial fleets, and public transport vehicles.

2. Objective

• To detect alcohol consumption in the driver using an MQ-3 gas sensor.

• To prevent the engine from starting if alcohol is detected.

• To notify a remote server or mobile application via IoT (using Wi-Fi module ESP8266 or NodeMCU).

• To enhance public safety by implementing smart vehicle safety technology.

3. Components Required

• Arduino Uno / Arduino Nano

• MQ-3 Alcohol Sensor

• ESP8266 Wi-Fi Module (or NodeMCU)

• Relay Module (to simulate engine lock mechanism)

• 12V DC Motor (to simulate engine start)

• Buzzer and LEDs (for alerts)

• Power Supply (Battery or Adapter)

• Jumper wires, Breadboard or PCB

4. Working Principle

1. The MQ-3 sensor continuously monitors the driver’s breath for the presence of alcohol vapor.

2. If the alcohol level crosses a predefined threshold, the Arduino triggers:

   • A relay module to cut off the ignition circuit (simulated via a DC motor).

   • A buzzer and LED alert system for immediate visual and audible warning.

3. Simultaneously, the system sends a notification (e.g., to a web server or mobile app) using the ESP8266 Wi-Fi module, logging the event with a timestamp and location (optional if GPS is included).

4. If no alcohol is detected, the engine is allowed to start as usual.