NCJ Number
178811
Journal
Security Management Dated: September 1999 Pages: 129-133
Date Published
September 1999
Length
4 pages
Annotation
Technologies used in breath alcohol detection systems are described, and their relative advantages and drawbacks are noted.
Abstract
Four major technologies are used in breath alcohol testers: electrochemical fuel cells, metallic oxide semiconductors, infrared absorption, and disposable color change testers. The fuel cell consists of a porous, chemically inert layer coated on both sides with a finely partitioned platinum known as platinum black. The porous layer is impregnated with an acidic electrolyte solution. Platinum wires are connected to the platinum black surfaces. The entire assembly is mounted in a plastic case that incorporates a gas inlet and allows a breath sample to be introduced. The metal oxide semiconductor sensor is a solid-state device composed mainly of sintered tin dioxide that detects alcohol gas through an increase in electrical conductivity when the alcohol gas is absorbed on the sensor's surface. Infrared spectroscopy systems are based on the principle that certain liquids and gases, such as alcohol, have specific, predictable infrared absorption and reflection characteristics that can be observed and measured to detect and quantify the gases. Probably the easiest technology is the disposable breath tester that uses colorimetric technology. In a typical device, a person blows into a balloon and the mouthpiece of the balloon is then attached to one end of a glass tube containing bands of chemically treated yellow crystals. The breath sample is gradually released through the tube. If alcohol is present in the breath sample, a chemical reaction occurs and the crystals turn green. Positive and negative features of the four technologies are noted. 1 table and 1 photograph