New color-changing sensor detects alcohol with a smartphone snap

Osaka Metropolitan University researchers have developed a smartphone-compatible alcohol sensor that can visually detect a full range of ethanol concentrations, without the need for complex electronics or lab tools. Their technology allows for a broad array of potential applications in environmental monitoring, healthcare, industrial processes, and alcohol breath analysis.

Ethanol is used widely in food, pharmaceuticals, and fuel. It is also the intoxicating ingredient in many alcoholic beverages. Accurate detection of ethanol concentration, particularly in products containing both ethanol and water, is crucial for product hygiene management and quality maintenance.

"Conventional sensors typically require power sources and complex electronics, limiting their accessibility for everyday use," said Kenji Okada, an associate professor at Osaka Metropolitan University's Graduate School of Engineering and lead author of this study.

Seeking both selectivity and practicality, the team fabricated a portable and highly sensitive ethanol sensor built from a copper-based metal-organic framework (MOF) thin film called Cu-MOF-74.

These MOFs contain nanometer-sized pores that absorb ethanol molecules and respond with a visible color change -- a phenomenon known as solvato/vapochromism. Thanks to its low light-scattering properties and high transparency, the Cu-MOF-74 film enables precise optical measurements without the need for complex lab equipment.

"Our sensor changes color in response to varying ethanol levels across the full concentration range, even at low concentrations," Okada said.

What truly sets this technology apart is its integration with a smartphone app. Users can simply snap a photo of the film to measure ethanol concentration, making it a portable and accessible tool for use in the field, factories, or healthcare settings.

The researchers' findings offer a smarter, simpler, and more reliable approach to alcohol sensing. From the quality of your drink to the potential future of portable breath tests, this new sensor technology brings us a colorful step closer to real-time alcohol monitoring in everyday life.

"We hope our study could open up a wide range of applications, from the food and beverage industry to environmental monitoring, industrial exhaust gas detection and alcohol breath analysis," Okada said.

The study was published in Small Science.