Alcohol BLOG

When looking at purchasing a handheld, a digital breathalyzer for the purposes of measuring or estimating Blood Alcohol Concentration (BAC) there are generally two types of technologies that you will run into:

    1. Fuel Cell Sensors

    2. Semiconductor Sensors
Fuel Cell Sensors

Breathalyzers that employ fuel cell technology offer an extremely high level of accuracy, sensitivity and reliability, yet are still handheld and portable.

These BAC breathalyzers are so proven that it is permitted in over 30 US states, to use approved fuel cell breathalyzers for roadside testing for the sake of gathering evidence of BAC.

A fuel cell breathalyzer works by measuring breath alcohol concentration through the amount of electrical voltage created when alcohol compounds are oxidized by the fuel cell sensors. The more alcohol that is present in the breath sample, the greater the voltage the fuel cell generates, leading to a higher reading.

Semiconductor Sensors

Although not as accurate or reliable as their fuel cell counterparts,  semiconductor breathalyzers — the reputable ones, not the ones you find at the dollar store — offer users a more affordable means to gauge their BAC.

Semiconductor technology uses an oxide sensor to measure the reactivity of the tin dioxide (SnO2) in the sensor and the ethanol molecules in the breath sample. When the ethanol molecules come into contact with the tin dioxide the reaction changes the electrical resistance of the sensor. The semiconductor measures this difference and calculates an estimate of the BAC of the sample (the key word there being an estimate).

Although semiconductor breathalyzers are not quite as accurate as fuel cell breathalyzers, the lower cost makes them ideal for personal use. The higher quality ones can also be used for limited clinical or workplace alcohol testing.

Advantages of Fuel Cell Technology over Semiconductor Technology
    • Fuel Cell Breathalyzers are always and only alcohol-specific while semiconductor breathalyzers will sometimes react to perfume, hairspray, gasoline, cigarette smoke, and breath substances such as acetone and ketones, even when no alcohol is present.
    • Fuel Cell Breathalyzers are consistently accurate across an alcohol concentration range from .000 to .400 BAC. Fuel Cell Breathalyzers can also report 3-digit BAC measurement accuracy, unlike semiconductor devices.
    • Most fuel cell breathalyzers require recalibration only once per year or per 500 uses under normal use. Semiconductor sensors experience more drift, which occurs when there is a wider variety of the results over time and accumulated uses and needs to be recalibrated more frequently.
    • Fuel Cell breathalyzers have an expected working life of 3-5 years, while Semiconductor devices have a shorter lifespan.
    • With Fuel Cell technology, you know you are using the same technology used in portable breath testing by Law Enforcement agencies all over the world.
    • Fuel Cell breathalyzers require only a short startup time and are able to take many consecutive readings without breaks. A medium range semiconductor breathalyzer can take up to 20 consecutive samples but then a break of at least a couple of hours is required because with each sample being taken the amount of tin dioxide that remains in the sensor decreases. When the tin oxide has been depleted, the breathalyzer can no longer measure breath alcohol until atmospheric oxygen oxidizes it again to replenish it.
Advantages of Semiconductor Breathalyzers

Semiconductor breathalyzers aren’t without their own advantages.
    • The lower cost of manufacturing these devices results in a more affordable device than a fuel cell breathalyzer.
    • Semiconductor sensors require less power to run, making them highly portable.
    • The relatively low cost and small size of these breathalyzers make them ideal for consumers who want to estimate their breath alcohol instead of accurately measuring it.

Use common sense when purchasing a semiconductor breathalyzer. A $5 keychain that promises to give you a BAC reading is likely not accurate. Even the least expensive semiconductor breathalyzers that have any reliability will still cost $30 or more.