A new sensor, hardly bigger than an old-fashioned silver dollar, can detect blood-alcohol levels in a moving vehicle and may help keep drunken drivers off the road.

Developed by electrical engineering Professor Jonathan Bredow and civil engineering Professor Sia Ardekani, along with researchers from Texas Christian University and Texas Southern University, the sensor works much like a miniaturized Breathalyzer, sniffing alcohol on a subject's breath. It attaches to the dashboard or windshield and sends a wireless signal to a receiver when activated.

Initially, researchers thought police might use the device to pre-empt drunken driving, but privacy and civil rights concerns make that unlikely. However, the sensor could be installed by parents to monitor their teen-agers, or by trucking companies to keep tabs on commercial drivers.

As an expert on traffic safety, Dr. Ardekani became involved with the project two years ago for its potential to reduce the large number of alcohol-related traffic fatalities. According to the National Highway Traffic Safety Administration, in the year 2000 alone 16,653 people died in crashes involving alcohol.

A major automotive technology company based in Michigan has contacted the professors about commercializing the device. They expect the sensor, which could cost as little as $100, to be on the market within four years.