How the iBreath Alcohol Breathalyzer Works

Using the iBreath Alcohol Breathalyzer

To use the iBreath, you first have to make sure it's drawing power. The iBreath doesn't have its own batteries, but there are several ways to power the device:

  • Plug it into an iPod or iPhone.
  • Use a USB cord and connect the device to a computer.
  • Use the provided 12-volt car plug and connect the iBreath to your vehicle.

Once the iBreath has power, it's ready for operation. To use the breathalyzer function, you need to unfold the blow wand from the device. Next, you press the ENT button on the iBreath and a 10-second countdown begins. During this countdown, the tiny heating element inside the iBreath warms the gas sensor tin dioxide membrane to the appropriate temperature.

Once the sensor is ready, it's time to breathe into the wand. You need to blow a steady stream of air into the wand for about 10 seconds. The semiconductor chip will react to any alcohol in your breath and measure the resulting change in resistance. The LED screen will display your estimated BAC. If it's near or above .08, you shouldn't even think about getting behind the wheel of a car.

The iBreath also has a simple timer function that will help remind you to test your BAC again. If you've had one beer too many, you may need to take another test in about an hour. Setting the timer on the iBreath will help keep you on track. When the timer goes off, you can repeat the test.

If you want to use the FM transmitter, simply push the Mode button on the device. The iBreath has two tuning buttons that let you adjust the frequency of the transmitter so you get the best result. Using a combination of these buttons and the ENT button will let you set the radio frequency. Once you find an available channel, pressing the lock button will keep the device tuned to that frequency even if you accidentally hit one of the other buttons.

Using devices like the iBreath can help prevent you from making a serious mistake in judgment. Remember that driving under the influence is both dangerous and illegal.

For more about gadgets and other related topics, follow the links below.

Related HowStuffWorks Articles


  • "Alcohol Gas Sensor."
  • "iBreath Breathalyzer & FM Transmitter for iPod & iPhone." (April 21, 2009)
  • Stowell, A.R.,  A.R. Gainsford and R.G. Gullberg. "New Zealand’s Breath and Blood Alcohol Testing Programs: Further data analysis and forensic implications." Forensic Science International, Vol. 178, Issue 2, pp. 83-92. July 4, 2008.
  • Yean-Kuen, Fang et al. "Integrated ethanol gas sensor and fabrication method thereof." U.S. patent 6,161,421. Dec. 19, 2000.