DIY Breathalyzer Using Arduino UNO

Today I am going to discuss how to make a very simple DIY Breathalyzer using Arduino UNO and few external components. Ana Carolina designed this project as an instructableΒ in This is a low-cost project and a useful one too. If you have no idea about what breathalyzerΒ is, let me explain briefly:Β A breathalyzerΒ is a device for estimating blood alcohol content (BAC) from a breath sample. Check the link given for more information.


  • Arduino Uno
  • MQ-3 Alcohol Sensor
  • 128Γ—64 LCD (Liquid Crystal Display)
  • 7 Γ—Β 330 Ohm Resistor
  • 7 Γ—Β LEDs (1 Red, 2 Yellow, 3 Green and one other color)
  • Jumpers Wires
  • Breadboard
  • Soldering Iron (optional)
  • Solder Wire (optional)


This project is very simple. Here we are using an array of six LEDs and a 128Γ—64 LCD to display the alcohol level. The presence of alcohol is sensed by an MQ-3 alcohol sensor and then analyzed by an Arduino board. We are using Arduino UNO in this project, but any model can do the job.

Three Green LEDs represent that alcohol level is OK and within the safe limit. TwoΒ Yellow LEDs are used to describe that safe limit is going to be reached, and you know it well why the Red LED is there. In fact, those LEDs are used just to give you a quick idea. If you want to know the exact value, the display is there for you.

You can tweak the program and re-calibrate the breathalyzer. But you must remember that breathalyzer doesn’t precisely measure your blood alcohol content,Β rather it estimates a value from the amount of alcohol in your breath.

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