You've been at a party and get pulled over on the way home. You've only had a few, but the officer wants to check your blood alcohol level just to make sure. You're probably not thinking about it at the time, but how does it work? How can a little machine you blow into tell how much alcohol you've consumed?
Spectrophotometer
The spectrophotometer is a table-top machine. You can generally find one only at the police station. When you blow into a spectrophotometer, the machine will identify molecules by how the infrared light in the machine absorbs them. The ethanol (alcohol) in your breath is then singled out and measured.
Fuel-Cell Sensor
Fuel-cell sensors are portable and are commonly seen at roadside sobriety checkpoints. Fuel-cell sensors measure ethanol by creating a chemical reaction when blown into that oxidizes the ethanol in the breath and creates an electrical current. The greater the current, the more you've had to drink.
Semiconductor Oxide Sensor
The semiconductor oxide sensor is a more affordable type of breathalyzer. A sensor is built in that is specifically designed to sense ethanol and measure it. Oxide-based testers are relatively new and very affordable. The Alcohawk series of testers employs semiconductor oxide technology. Because it is small, many law enforcement professionals are now carrying a semiconductor oxide sensor as a preliminary test for roadside sobriety.
