Breath Alcohol Testers: Technology, History, and Future

Background

Ensuring alcohol‑impaired drivers stay off the road is a critical public safety priority. In 2000, 41,812 highway deaths were recorded in the United States, 40% (16,725) involving alcohol—a slight increase from the previous year. One death occurs every 32 minutes, and an injury every 26 seconds in alcohol‑related accidents.

How Breath Alcohol Testers Work

Breath alcohol testers (BATs) rely on the blood‑to‑breath ratio, universally accepted at 2,100:1. This means 2,100 mL of deep lung air contains the same amount of alcohol as 1 mL of blood. The ratio is governed by Henry’s Law, linking gas solubility to partial pressure.

To obtain accurate readings, BATs sample deep lung air. Each lung houses millions of alveoli where gas exchange occurs. Devices require a sustained exhalation to capture this air; otherwise, the sample may be diluted with lower‑concentration air.

There are two primary BAT technologies:

• Infrared: Breath passes through infrared light tuned to alcohol’s absorption frequency. The remaining light indicates alcohol concentration.
• Fuel‑cell: Alcohol serves as fuel for a chemical reaction that generates electricity. The current produced correlates with breath alcohol content.

Fuel‑cell BATs are the most common due to their accuracy, portability, and lower cost compared to infrared units.

Historical Milestones

Hippocrates noted that breath could reveal health conditions. Modern BATs trace back to 1938 when Dr. R. N. Harger introduced the Drunkometer. Subsequent devices—Intoximeter (1941), Alcometer (1941), and the portable Breathalyzer (1954 by Robert Borkenstein)—gradually replaced blood and urine tests, which were slower and more expensive.

Early models required a balloon exhalation to capture deep lung air, but alcohol in mouthwash or other substances could skew results. The 1980s saw a shift toward fuel‑cell and infrared technologies, driven by demands for speed, reliability, and courtroom admissibility.

Materials and Design

Fuel‑cell BATs consist of a platinum‑coated fuel cell, a pump, a mouthpiece, a printed circuit board (PCB), and an LCD or LED display housed in a low‑density polyethylene (LDPE), polypropylene (PP), or polystyrene (PS) case.

The fuel cell uses two electrodes in an electrolyte; alcohol is drawn in, reacts chemically, and produces an electrical current measured by the device.

BATs are categorized as:

• Evidential: Large, desktop‑size units used in police stations; results are court‑admissible.
• Screening: Portable, calculator‑sized devices for on‑the‑go testing.
• Passive: Handheld units that sample ambient air without user exhalation.

Manufacturing Process

1. Case fabrication: LDPE, PP, or PS pellets are melted, injected into a mold, and cooled into shape.
2. PCB assembly: Fiberglass epoxy with copper traces, pre‑assembled with battery springs.
3. Pump construction: A 3‑V motor drives a stainless‑steel screw that pushes breath through the fuel cell via a Pyrex cylinder and nylon piston.
4. Assembly: Pump, PCB, LCD, and fuel cell are mounted inside the case; connections are soldered and secured.
5. Calibration: The BAT is exposed to a known alcohol concentration (test gas or solution) and automatically adjusts internal parameters.
6. Testing: Manufacturers run 50‑plus cycle tests to verify deep‑lung detection and accuracy.
7. Certification: Devices are shipped to the U.S. Department of Transportation (DOT) for performance validation and to secure placement on the Conforming Products list.
8. Packaging: Approved BATs are boxed and distributed to wholesalers or directly to customers.

Quality Control and Certification

Each BAT features a self‑diagnostic PCB that triggers alerts for insufficient deep‑lung exhalation and logs air flow. Manufacturers conduct rigorous simulation testing—often 200 cycles—using a wet‑bath or gas simulator to compare device readings against known alcohol concentrations across a temperature range (50°F to 86°F).

The DOT requires that BATs differentiate alcohol from acetone at low concentrations (0.02 % v/v) and that law enforcement operators obtain certification before use.

The Future of Breath Testing

Portable, low‑cost fuel‑cell devices are becoming the standard for both law enforcement and consumer markets. Hand‑held units allow individuals to verify legal limits, while establishments that sell alcohol can provide on‑site testing. Although slightly less precise than professional‑grade instruments, these consumer BATs offer accessibility and affordability.

DOT regulations mandate random alcohol testing for millions of safety‑sensitive employees across trucking, aviation, rail, transit, and maritime industries. Non‑regulated companies increasingly adopt such testing to promote workplace safety.

State legal limits in 2001 averaged 0.10 BAC, with many states enforcing 0.08 BAC, equating to 10 or 8 mg of alcohol per 100 mL of blood.

Further Reading

Books

Considine, Douglas M., ed. Van Nostrand’s Scientific Encyclopedia. 8th ed., New York: International Thomson Publishing Inc., 1995.

Periodicals

National Center for Statistics and Analysis. Motor Vehicle Traffic Crash Fatality and Injury Estimates for 2000, 2000 Annual Assessment of Motor Vehicle Crashes.

Online Resources

“About Breath Tests.” Menssanna Research, Inc. December 2001.

Craig C. Freudenrich. “How Breathalyzers Work.” How Stuff Works December 2001.

Life Loc Technologies, Inc. Web Page December 2001.