Earmuffs capable of detecting how drunk a person is have been created by Japanese scientists and could eventually replace the breathalyser.
The technology is in its early stages but was found to be accurate and effective in a small trial run by the Tokyo Medical and Dental University.
The new device fits over a person’s ears and enables non-invasive measurement of real-time changes in blood alcohol levels by detecting gases seeping out of a person’s skin.
Professor Kohji Mitsubayashi modified a pair of commercial earmuffs to collect ethanol vapour and tubes were added to carry it to an intricate set of sensors. Future, custom-built advances could allow for this to be done in a self-contained unit.
“If the sensor detects ethanol vapour, it releases light, the intensity of which allows for ethanol concentrations to be calculated,” Prof Mitsubayashi said.
"As previous research found that ethanol concentrations in the breath and blood are correlated, this indicates that the device could be used instead of a breathalyser to estimate blood alcohol levels.”
Three male volunteers were recruited for the study, which has been published in Scientific Reports, and drank alcohol before being asked to don the prototype headgear for 140 minutes.
Concentrations of the ear-derived results were compared to breath samples taken at the same time. This showed the earmuff and breath methods both respond similarly, with an ethanol signal peaking around 13 minutes after a person ingests an alcoholic drink.
British entrepreneur Peter Cadbury demonstrating how to use one of his breathalysers in 1967
Credit: Hulton Archive
Data show the strength of the ear signal is 590 times weaker than that of breath, but it is still far more potent than ethanol gas emitted by other body parts.
One reason the ears offer a potential alternative to breathalysers is that they don’t get particularly sweaty, as sweat interferes with the ethanol vapor reading.
Therefore, body parts with more active sweat glands are less viable as an alcohol-detecting alternative to exhaled breath.
Ears, however, have a far lower density of sweat glands compared to other body parts. The auditory organ contains 140 glands per centimetre, almost half that of the forearm (225), a third as many as cheeks (360) and four times less than the palm (620).
"The average highest concentration of ethanol released through the ears was found to be 148 parts per billion, double the concentration previously reported to be released through the skin of the hand," the researchers said.
The researchers proposed that the device could also be used to measure other gases released through the skin, for example in disease screening, and would only require a different enzyme to be used to switch from spotting ethanol to identifying other chemicals or biomarkers.