There are already in-vehicle systems that keep people from driving while intoxicated, although most of them require users to blow into a breathalyzer. The prototype AlcoStop system, however, takes a less intrusive approach – it measures users' blood alcohol levels by analyzing their sweat via built-in sensors, and won't allow the car to start if those levels indicate that they're too drunk to drive.
AlcoStop was developed by a team of eight students from Mexico's Institute of Technology of Cintalapa, and incorporates sensors in the steering wheel, shift lever and seat.
Not only will it keep the car from starting, but using an accompanying app it can also automatically send a message to the user's family or friends, letting them know that the person is now car-less and needs a ride. Hopefully that feature is optional, given that many users might just want to get a taxi instead of announcing their inebriation to everyone.
The final version of the system is envisioned as being an aftermarket product that users could buy and easily install in their own vehicle. Given that the type of people who would think to do so are probably already fairly responsible and not inclined to drink and drive, though, it might be better as a factory-installed standard feature.
The students are now working at refining the sensors in order to work with a wide range of perspiration levels, and are planning on forming a company to commercialize the technology by the end of the year.
Source: Investigacion y Desarrollo (Spanish)