A better breathalyzer: Gel-filled gemstones make new reusable tool for detecting alcohol vapor concentration

Oct 08, 2013
The opal-based alcohol sensor is green before use but turns redder in the presence of alcohol vapor. Credit: Riccardo Pernice, Università degli Studi di Palermo

To gauge whether suspects involved in accidents or routine traffic stops have been driving drunk, police officers pair field sobriety tests with breathalyzers, which signal the presence of alcohol in the breath. Most breathalyzers are expensive and unable to test for precise concentrations of alcohol. Offering a better solution, Italian researchers have developed a novel idea for an inexpensive, portable breathalyzer whose color would change from green to red with higher alcohol concentrations. But unlike current color change-based devices, this sensor would be reusable and could also provide a precise digital readout.

The new design is the first to use the sensing properties of opals, a type of gemstone, to detect the gas version of , the intoxicating component of commercial liquor, by inducing a change in color that is visible to the human eye. The research team describes their new method in a proof-of-concept paper published today in The Optical Society's (OSA) journal Optical Materials Express.

The portable breathalyzers preferred by roadside police use expensive electronic readouts, but these devices lack the "immediate and intuitive" color change that tells police whether the alcohol content of a suspect's breath puts them in the legal red zone, said first author Riccardo Pernice of the Università degli Studi di Palermo in Italy. Techniques that do use color change to assess the level of alcohol concentration are typically less expensive, but they cannot give a precise reading of the and most are use-once-and-toss. Pernice said his team's proposed device combines the best elements of each of these two breathalyzer models.

The opal-based alcohol sensor is green before use but turns redder in the presence of alcohol vapor. Credit: Riccardo Pernice, Università degli Studi di Palermo

"Our approach enables an optical, naked-eye detection as a color change from green to red, like litmus paper," Pernice said. "But it also potentially permits accurate quantitative measurements" with the addition of an electronic system or a color detector.

The method is inspired by the natural behavior of opals, gemstones whose iridescence illustrates their ability to manipulate light. Scientists use manufactured versions of opals and other photonic crystals to detect acidity or the presence of liquid ethanol, but until now little attention has been paid by researchers to detecting gaseous ethanol, the researchers said.

In their new setup, the researchers created sheets of manufactured opal about one centimeter square and just a few hundred billionths of a meter thick, as thin as some of the films on soap bubbles. The opals are pumped full of a gel tuned to respond to ethanol vapor. At increasing ethanol concentrations, the gel swells, changing the way light travels through the gel-filled opal and causing the sample to become red.

This is a closeup of the surface of the opal, taken with a scanning electron microscope. The ethanol-responsive gel used in the device would fill the spaces between the rows of regularly spaced nanoparticles that comprise the opal. Credit: Riccardo Pernice, Università degli Studi di Palermo

The change in color is clearly visible to the naked eye, Pernice said and the device is usable multiple times. After performing the measurements, researchers found that the sample gradually regained its original green after less than one minute of exposure in air. He added that the sensor does not pose environmental concerns for disposal after use, since it is made of all non-toxic materials, and that it also does not react to acetone, one of the many substances that can be falsely identified as ethanol by some breath machines.

The device is currently able to detect alcohol at much higher concentrations compared to other portable sensors. In the coming months, the researchers hope to explore the device's use at lower concentrations as well.

Explore further: Haunting tales in ship-wrecked silver

More information: "Opals infiltrated with a stimuli-responsive hydrogel for ethanol vapor sensing," R. Pernice et al., Optical Materials Express, Vol. 3, Issue 11, pp. 1820-1833 (2013). www.opticsinfobase.org/ome/abs… fm?uri=ome-3-11-1820

Related Stories

Team develops device to detect biodiesel contamination

Sep 05, 2013

In 2010, a Cathay Pacific Airways plane was arriving in Hong Kong when the engine control thrusts seized up and it was forced to make a hard landing—injuring dozens. The potential culprit? Contaminated fuel.

Alcoholic fly larvae need fix for learning

Nov 29, 2012

Fly larvae fed on alcohol-spiked food for a period of days grow dependent on those spirits for learning. The findings, reported in Current Biology on November 29, show how overuse of alcohol can produce lastin ...

Luminous bacterial proteins detect chemicals in water

Jun 12, 2013

While residual medications don't belong in the water, trace metals from industrial process waters handled by the recycling industry are, in contrast, valuable resources. Scientists at the Helmholtz-Zentrum ...

Recommended for you

The origins of handedness in life

16 hours ago

Handedness is a complicated business. To simply say life is left-handed doesn't even begin to capture the blooming hierarchy of binary refinements it continues to evolve. Over the years there have been numerous ...

Have our bodies held the key to new antibiotics all along?

19 hours ago

As the threat of antibiotic resistance grows, scientists are turning to the human body and the trillion or so bacteria that have colonized us—collectively called our microbiota—for new clues to fighting microbial infections. ...

Characterizing an important reactive intermediate

Oct 01, 2014

An international group of researchers led by Dr. Warren E. Piers (University of Calgary) and Dr. Heikki M. Tuononen (University of Jyväskylä) has been able to isolate and characterize an important chemical ...

Surfaces that communicate in bio-chemical Braille

Oct 01, 2014

A Braille-like method that enables medical implants to communicate with a patient's cells could help reduce biomedical and prosthetic device failure rates, according to University of Sydney researchers.

User comments : 0