How does it work? The label includes gold nanorods.

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Is the milk on the date or not? At present there is only one way to find out: open the pack. But science comes up with an agreeable solution: a smart color-changing label on the packaging that tells you whether the food is still good.
The label in question is gel-like and about the size of a grain of corn. When food is fresh, the tag is red. But as time passes, it changes color: it is orange, yellow and finally green. The latter means that the food is spoiled.
How does it work? The label includes gold nanorods. "The gold nanorods that we use, are naturally red," explains researcher Chao Zhang from. "In the labels is also silver and silver chloride, which reacts slowly and controlled. Over time, the silver deposits on the nanorods. As a result, the chemical composition and shape of the particles and will also change the color of the tag otherwise. The silver layer is getting fatter dne over time, so that the color of the original red turns into orange, yellow and green and eventually blue and violet. "The labels that actually mimic the time after that need to microbes in a particular type of food to grow. The labels also take into account fluctuating temperatures that can cause food for accelerated (eg the expiry date) spoils. "If the label for example, that the product dne is still two weeks in the freezer can be preserved, but the tag is now orange, it means that the product will actually only half as fresh as the label indicates. In that case, consumers dne know that the product only seven days is edible. "
Cheap The label that the researchers presented at a meeting of the American Chemical Society, was developed especially for milk. But according to the researchers, it is very easy to modify the tag so that the shelf life of a wide range of products - including medications - can monitor. In addition, the tag is also a surprisingly cheap: about $ 0,002 each.
"The researchers have already applied for a patent dne in China in the tag. They are now looking for products dne that can go use the tag on a large scale. "Well again I am skeptical, who told me that a country like China where food scandals are the order of the day, to trust the labels.
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