How Does a Breathalyzer Work?

How Does a Breathalyzer Work
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If you’re wondering how a breathalyzer works and how effective it is in determining if the driver is too intoxicated to get behind the wheel, we will help you answer those questions.

Drunk driving is one of the most common causes of road accidents. In fact, in 2015, over 10,000 people were killed in alcohol-impaired crashes in the United States alone. That makes up almost 30% of all road deaths in the US. This is why cops are extra vigilant these days in catching drunk drivers.

They use a battery of methods and tools to pinpoint and catch drunk drivers so that they may not cause any more harm to themselves or others. One of those tools is the breathalyzer.

We see the breathalyzer in the media all the time. In movies and TV shows, we see cops administering breathalyzer tests to suspected drunk drivers. Many people who’ve never had to undergo the test themselves are often curious, asking “How does a breathalyzer work?” If you’ve ever been one of those curious people, you’re in luck because the answers are here.

What is a breathalyzer?

A breathalyzer is a device that is used in law enforcement to test the blood alcohol content (BAC) of a person using their breath. The term “breathalyzer” is actually a brand name for a device invented by a man named Robert Frank Borkenstein. The word is a portmanteau or a combination of the words breath and analyzer.

How does alcohol get into the breath?

A breathalyzer analyzes a person’s BAC in various ways. There are breathalyzers that use chemicals that change colors when they react with alcohol; intoxilyzers that can detect alcohol using infrared technology; and alcosensors, which sense chemical reactions of alcohol inside a fuel cell. But before going into the nitty-gritty, you might be asking how alcohol gets into the breath in the first place.

The alcohol that is found in drinks is called “ethanol,” and is composed of small molecules. Due to their size, these molecules are more easily absorbed from the mouth, throat, and stomach into the bloodstream. When our blood passes through our lungs, and we take a breath, the alcohol is vaporized, passed into the alveoli (or air sacs) and out of your body. The alcohol present in the air you exhale is what is tested in a breathalyzer.

How does a breathalyzer work?

How does a breathalyzer work? It depends on the device. Yet, though there are many different types out there, all with a similar mechanism—all devices are equipped with a mouthpiece which the test taker must breathe into. The air moves into a sample chamber, where the molecules are analyzed.

As mentioned above, there are three major types of breath testing devices for analyzing BAC. The mechanisms of these three will be explored below:

Alcosensor III or IV

Alcosensors make use of fuel cell technology. Fuel cells are usually used to convert hydrogen and oxygen into water, producing electricity in the process. This kind of technology is being studied for future use in powering our automobiles.

In an Alcosensor, the fuel cells have two platinum electrodes with a type of acid-electrolyte material in between them. When someone blows air containing enough alcohol into the mouthpiece, the platinum oxidizes the alcohol content into acetic acid, electrons, and protons. The more alcohol is available for oxidation, the stronger the electrical current. This current is then measured by a microprocessor, which determines the level of BAC in the person’s system.


Intoxilyzers use infrared spectroscopy to identify the amount of ethanol in a person’s system. This device measures wavelengths that are produced by the vibrating molecules.


Robert Frank Borkenstein’s breathalyzer used a photovoltaic assay. This technology is rarely used today, due to the ease and convenience provided by the Alcosensor and the Intoxilyzer. This works through the use of photocells which analyze color change brought about by a chemical reaction between the solution present in the device and the alcohol in the person’s breath.


If you’ve asked yourself “How does a breathalyzer work?” maybe you are already aware of what it’s used for. After all, it’s quite popular in media.

A person’s BAC is the key factor in determining intoxication. Putting someone through a breathalyzer test can help determine if a person is too intoxicated to function properly. Legally, certain things cannot be done under the influence of alcohol, such as driving a vehicle and operating heavy machinery. Thus, police put suspects through breathalyzer tests to see if they are fit to proceed with driving or operating their machines.

Since alcohol is easily detected through the breath, the breathalyzer is favored over taking urine or blood sample because the device can provide instantaneous results. This makes testing on the road easy and convenient. This device is important not only because it can help minimize injuries, it can also save lives.

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