Oxygen-sensing marker has anti-counterfeit applications

Researchers in China have developed smart labels that react to oxygen and could be used to detect foods that are counterfeit or have been tampered with.

The team from Xiamen University and the Fujian Research Institute of Metric Science are using honeycomb-like nanospheres - made from a commercially-available polymer - that change colour when exposed to oxygen.

The researchers note that many foods, including meats, potato chips and fruits, are kept in vacuum or an inert gas - such as nitrogen or carbon dioxide - to retain freshness and extend shelf-life. The oxygen-sensing nanoparticles can be used to detect tampering or adulteration of the package, they suggest, and also to distinguish between fake and genuine products.

"To the best of our knowledge, this is the first anti-counterfeit material that undergoes a colour transition stimulated by oxygen content," write the authors of the paper, which is published in the journal Sensors and Actuators B: Chemical (September 2016 edition).

They suggest that their technique for manufacturing the nanoparticles is relatively low cost and environmentally friendly compared to the production of other oxygen-sensing materials.