Detecting alcohol with a colour-changing sensor
Researchers at Osaka Metropolitan University 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. Described in the journal Small Science, the technology allows for an array of potential applications in environmental monitoring, health care, industrial processes and breath analysis.
Ethanol is used widely in food, pharmaceuticals and fuel, as well as 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. But as noted by lead author Associate Professor Kenji Okada, “Conventional sensors typically require power sources and complex electronics, limiting their accessibility for everyday use.”
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 nanometre-sized pores that absorb ethanol molecules and respond with a visible colour 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 colour in response to varying ethanol levels across the full concentration range, even at low concentrations,” Okada said.
The technology has even been integrated 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 thus offer a smart, simple and reliable approach to alcohol sensing. From the quality of your drink to the potential future of portable breath tests, the sensor technology brings us one 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.
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