Developed at Imperial College London, the prototype PEGS (paper-based electrical gas sensors) cost $0.02 each to make and can detect spoilage gases like ammonia and trimethylamine in meat and fish products. Imperial’s PEGS are detailed in ACS Sensors.
The sensors, made by printing carbon electrodes onto cellulose paper, are combined with NFC (near field communication) tags that can be read by nearby mobile devices.
During laboratory testing on packaged fish and chicken, PEGS reportedly detected trace amounts of spoilage gases quickly and more accurately than existing sensors, at a fraction of their price. The researchers said the sensors - the first ever commercially-viable food freshness sensors - could eventually replace the ‘use-by’ date found on food packaging.
Lead author Dr Firat Güder, of Imperial’s Department of Bioengineering, said: “Although they’re designed to keep us safe, use-by dates can lead to edible food being thrown away. In fact, use-by dates are not completely reliable in terms of safety as people often get sick from foodborne diseases due to poor storage, even when an item is within its use-by.
“Citizens want to be confident that their food is safe to eat, and to avoid throwing food away unnecessarily because they aren’t able to judge its safety. These sensors are cheap enough that we hope supermarkets could use them within three years. Our vision is to use PEGS in food packaging to reduce unnecessary food waste and the resulting plastic pollution.”
Existing food spoilage sensors are not commonly used because they’re either too expensive (often comprising a quarter of overall packaging costs) or too difficult to interpret. According to Imperial, colour-changing sensors could increase food waste as consumers might interpret even the slightest colour change as ‘bad food’.
PEGs overcome current hurdles because they’re said to function at nearly 100 per cent humidity (most sensors struggle above 90 per cent); they work at room temperature and do not need to be heated, so they consume very low amounts of energy; and they are only sensitive to gases involved in food spoilage.
The authors hope that PEGS could have applications beyond food processing, like sensing chemicals in agriculture, air quality, and detecting disease markers in breath like those involved in kidney disease.