Hitachi and Honda have reveal a prototype of a portable alcohol detector that can be integrated into a smart key.

The prototype is tamper-resistant, able to distinguish human breath from any alternative gases, and is capable of distinctively detecting the saturated water vapour from human breath - accurately measuring alcohol levels within three seconds.

The two companies also developed a system that can show the alcohol level measured by the detector on a vehicle’s display panel. The system can become an ignition interlock to stop a vehicle from starting when it detects that the driver is under the influence of alcohol.

Currently other systems require drivers to perform the test from the driver’s seat once inside a vehicle, however the new prototype enables drivers to measure their alcohol level from anywhere prior to entering their vehicle, thus reducing the temptation to drive. In addition, it can confirm that the applied gas is human exhaled breath and can detect the level of alcohol present simultaneously - an enhancement over currently available devices.

The device uses a miniaturised sensor which consists of an oxide insulator sandwiched between electrodes. Breath is absorbed by the insulator and electric current flows between the electrodes.

This sensor improves upon previous similar devices by being able to detect alcohol to a high degree of accuracy, despite the sensor area measuring just 5mm square. Using three types of semiconductor gas sensors to detect ethanol, hydrogen and metabolised acetaldehyde, this method improves the accuracy threefold compared to devices that only use an ethanol sensor for measurement.

The technology is capable of measuring as little as 0.015 mg/L (an ethanol concentration) compared to 0.15 mg/L of the alcohol which constitutes being “under the influence of alcohol” and a charge of drunk driving in Japan.

By applying the recorded measurement result of the alcohol detector into the engine ignition mechanism, the system prevents the vehicle’s engine from starting if it detects that the driver is over the preset limit. An alert indicator also shows the measurement results on the vehicle’s display panel if the detector equipped smart key is close to the driver seat.

Hitachi and Honda are aiming to commercialise the technology through effectively collecting data from future validation tests.