- Earmuffs detect ethanol compounds in gas released from ear skin
- In tests, the device measured alcohol intake as well as a traditional breathalyzer
- While earmuffs take longer to produce results, breathalyzers are more aggressive
If a new device is revealed, suspected drink drivers may soon be asked by police to put on a pair of earmuffs.
Japanese scientists have developed a pair of earmuffs that can estimate blood alcohol levels based on ‘transcutaneous gas’ – a gas released through the skin.
Earmuffs presented as proof-of-concept in a new study detect ethanol compounds in the transcutaneous gas released by the ears.
In tests, the device measured alcohol intake as well as a traditional breathalyzer, though the process took much longer—more than two hours, compared to just a few breathers stopped by the roadside. It can only be minutes.
A schematic image of the monitoring system for outer ear-derived ethanol consisting of earmuffs and an ethanol vapor sensor (Bio-Sniffer)
But a breathalyzer test is more invasive, often requiring a tube to be inserted into the mouth.
In addition, products such as mouthwash or breath spray can ‘fool’ some breathalyzers by significantly increasing test results. For example, Listerine mouthwash contains 27 percent alcohol.
It also measures other chemical compounds – acetone (a marker of lipid metabolism) and acetaldehyde (a known carcinogen detected in the body after drinking).
The device has been developed by a Japanese team led by Kohji Mitsubayashi at Tokyo Medical and Dental University.
They say in their study, ‘We have investigated the possibility of external ears for stable and real-time measurement of ethanol vapor.
‘For stable monitoring of transcutaneous gas, it is necessary to locate the body part with little interference on the measurement.
‘Transcutaneous gas is more suitable for real-time and continuous evaluation than breath.’
Chemical compounds released through the skin reflect the chemical compounds present in the blood circulation in the body – including alcohol (ethanol).
Of course, breath measurements and ‘transcutaneous gas’ are not as accurate measurements of blood alcohol levels as blood and urine samples (although these are far more invasive).
alcohol and breathalyzer
Alcohol, also known as ethanol, is the main component of alcoholic beverages such as beer, wine and liquor.
When you drink an alcoholic beverage, it is absorbed into your bloodstream and processed by the liver.
As the alcohol in the blood travels to the lungs, some of it will evaporate into the air in the small sacs of the lungs known as the alveoli, and pass out of the body (‘alcohol breath’).
It is alcohol that a respirator is designed to measure. This is why it is essential to measure deep lung air when using a respirator.
While a breath analyzer gives rapid results, it is not as accurate as measuring blood alcohol.
So no breath test is as accurate as a blood or urine test.
The team’s equipment consists of a modified pair of commercial earmuffs that collect gas released through the skin of a person’s ears, and an ethanol vapor sensor.
If the sensor detects ethanol vapor in the gas, it emits light of varying intensity, which is . it depends on Ethanol concentration detected.
In the experiments, the authors used their instrument to continuously monitor ethanol vapor released through the ears of three male volunteers.
First, the base ethanol concentration from the transcutaneous ear gas was measured for 10 min without drinking alcohol.
The volunteers then drank alcohol at a concentration of 0.4 grams per kilogram body weight within five minutes, and the measurement continued for another 140 minutes.
Volunteers’ breath ethanol concentrations were also measured at regular intervals using an additional ethanol vapor sensor and a device containing reagents that change color when exposed to ethanol.
The authors observed that changes in the concentration of ethanol released through the ear and breath were similar over time for all volunteers.
As previous research found that breath and blood ethanol concentrations are correlated, this indicates that the device may be used instead of a breathalyzer to estimate blood alcohol levels.
The results for the earmuffs were comparable to those of a breathalyzer—but a breathalyzer test is much more invasive, requiring a tube to be inserted into the mouth. In the picture, an Australian officer is using a breath analyzer on a driver, as mouthwash or breath spray can ‘fool’ some breathers by amplifying test results. For example, Listerine mouthwash contains 27 percent alcohol.
The average highest concentration of ethanol released through the ears was found to be 148 parts per billion.
Previous devices have used a hand to measure blood alcohol levels as a less invasive alternative to inserting a tube into one’s mouth.
But 148 parts per billion, twice as much as previously reported to be released through the skin of the hand, the researchers say, suggest the ear may be more appropriate.
In addition, sweat from the sweat glands in the hand can interfere with the readings, the researchers explain. In comparison, the external ear canal does not contain an eccrine sweat gland.
“The density of sweat glands and the epidermis layers of the skin is different in each part of the body,” he says. ‘Therefore, choosing an appropriate body area is important.’
The authors also propose that the device could be used to measure other gases released through the skin, for example in disease screening.
The study has been published in scientific report.
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