A team of MIT chemists has developed a small sensor that's capable of telling consumers whether the meat in their refrigerators is safe to eat. The team believes that the inexpensive device, which makes use of modified carbon nanotubes, could help cut down on food waste.
The idea behind the sensor focuses on chemically altering carbon nanotubes so that their ability to carry an electric current is inhibited when a certain gas is present. The nanotubes were modified with metal-containing compounds known as metalloporphyrins, in this case containing a single cobalt atom bound to numerous nitrogen-containing rings.
That compound is effective at binding to compounds known as biogenic amines, such as cadaverine and putrescine, which are produced by meat when it starts to decay. When these gases are present, the the electrical resistance in the carbon nanotube is increased, with the reaction easily measured to provide feedback to the user.
The sensor was tested on pork, beef, chicken, salmon and cod, successfully detecting decay in the samples when left unrefrigerated.
The sensors are cheap and easy to manufacturer, use very little power, and do not require any expertise to use. As such, the team believes that the devices could be incorporated into the packaging of meat products, allowing them to offer much more accurate safety information than a standard expiry date.
This isn't the first time we've seen carbon nanotubes put to work checking that produce is fresh. Back in 2012, MIT developed a similar sensor that uses the same concept, in that case watching out for the gas ethylene, which causes fruit to begin to ripen.
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