How Does a Breathalyzer Work?

Updated 10/18/24

You might have seen breathalyzers at DUI checkpoints or in campaigns about responsible drinking. Perhaps you’ve blown into one before. But have you ever wondered, “How does a breathalyzer work?”

Our guide will walk you through the ins and outs of breathalyzers, including what they are and how they measure your breath alcohol content (BrAC). Plus, we’ll talk about how you can find an affordable Ignition Interlock or portable alcohol monitoring solution if you’re dealing with the consequences of a DUI.

What Is a Breathalyzer?

Breathalyzers are handheld devices that detect the level of alcohol in a person’s breath (also known as breath alcohol content or BrAC). When someone has consumed alcohol, their bloodstream carries it into their lungs (among other places), leading to the presence of alcohol in their breath.

Scientists began using chemical reactions to measure alcohol in a person’s breath as early as the 1920s. Indiana University researcher Rolla N. Harger released a prototype intoxication-measurement device in 1931, called the “drunkometer.” By 1958, Robert Borkenstein, a forensic scientist working for the Indiana State Police, had refined Harger’s design into a more modern form with a catchier name: the Breathalyzer.

The new tool quickly gained widespread use among law enforcement, who had previously lacked an easy and scientific way to determine whether a driver was impaired. The technology continued to improve as US states stepped up the fight against drunk driving. Smart Start offers our latest car breathalyzer technology to help drivers with a DUI stay compliant and restore their driving privileges.

The Science Behind Breathalyzers

So, how does a breathalyzer work, exactly? Let’s look at the facts, beginning with the major parts that are inside a breathalyzer device.

The Parts of a Breathalyzer

Breathalyzers have the same basic parts inside. Here’s how each one works:

• Mouthpiece: The user breathes into this plastic tube, which helps ensure a controlled and consistent flow of air into the device.
• Sensor Module: The core technology of the breathalyzer, which uses either a fuel cell or infrared beam to detect alcohol in the breath sample.
• Microprocessor: A tiny computer chip that converts the reading from the sensor module into an estimated BrAC reading.
• Display: A small screen presents the results of the analysis. This user-friendly interface shows the BrAC level, providing instant results on the subject’s level of intoxication.

How a Breathalyzer Detects Alcohol

Of course, the core function of a breathalyzer is to detect alcohol — so how does a breathalyzer work to perform this task? It all depends on the technology inside the device’s sensor module.

• Fuel cell breathalyzers pass the breath sample through a catalyst of two platinum electrodes, creating an electrical current in the presence of alcohol. The stronger the current, the higher the concentration of alcohol in the subject’s breath.
• Infrared spectroscopy breathalyzers analyze samples using a beam of infrared light. The more light absorbed on certain wavelengths, the higher the alcohol concentration.

No matter which technology is used, the sensor module sends its data to the microprocessor for analysis, which is then expressed as breath alcohol concentration (BrAC).

How Is Blood Alcohol Content (BAC) Measured?

According to MedlinePlus, blood alcohol content (BAC), the standard metric of intoxication, measures grams of alcohol per 100 milliliters of blood. Thus, the BrAC of a person who blows a 0.08 on a breathalyzer is equivalent to .08 grams of alcohol per 100 milliliters of blood. That might not sound like a lot, but it’s enough to cause delayed reactions, reduced self-control, and impaired reasoning — which is why .08 is the legal standard for intoxicated driving in most US states.

Your BAC is determined by how quickly your body breaks down and eliminates the alcohol you consume. So it’s logical to wonder: How long can a breathalyzer detect alcohol? In some cases, it can be as long as 12 to 24 hours — but this depends on several factors, including your body weight and composition, your biological sex, and how much alcohol you’ve consumed. In rare instances, other things besides alcohol can set off a breathalyzer, too.

Sometimes, a law enforcement officer might ask you to come to the police station and take a blood test or urine test. This may happen, for example, if the officer suspects you might be under the influence of other substances. Note that many states will automatically suspend your license for refusing to take an evidential breath or blood test.

The Importance of Calibration and Maintenance

Breathalyzers are generally accurate — but they’re also sensitive instruments that need regular calibration and maintenance to ensure they provide accurate readings. With a Smart Start Ignition Interlock breathalyzer, you’ll visit a qualified technician near you every 30 to 90 days (depending on which state you live in) to have your breathalyzer calibration verified. This process involves adjusting and fine-tuning the device to accurately measure your breath alcohol concentration (BrAC) levels.

How Smart Start Advances Breathalyzer Technology

If you’re dealing with a DUI, staying in compliance with court requirements is a top priority. You might need to install an Ignition Interlock Device breathalyzer on your vehicle to maintain your driving privileges or use a Portable Alcohol Monitoring Device breathalyzer to demonstrate compliance when you’re not on the road.

Smart Start is one of America’s leading providers of alcohol monitoring technologies. We bring you easy, fast, and affordable ways to meet your alcohol monitoring requirements. Our expert Program Advisors can help with anything you need, from answering your questions about how a breathalyzer works to explaining your options for an Ignition Interlock Device.

Call us at (800) 831-3299 for a free, customized quote on your Ignition Interlock or other alcohol monitoring device. Can’t call right now? Just fill out our simple online form, and a Program Advisor will call back at your convenience.