In order to help discover spoilage and reduce food waste for supermarkets and consumers, researchers have developed new low-cost, smart phone-linked, eco-friendly spoilage sensors for meat and fish packaging.

One in three UK consumers throw away food just because it reaches the use-by date, but 60% of the £12.5 billion-worth of food we throw away each year is safe to eat.

The researchers, whose findings were published in ACS Sensors, say the sensors could also eventually replace the use-by date—a widely used indicator of being fresh and eatable.

The sensors cost two US cents each to make. Known as “paper-based electrical gas sensors (PEGS)”, they detect spoilage gases like ammonia (a poisonous gas with a strong unpleasant smell) in meat and fish products. The information provided by the electronic nose is received by a smart phone, and then you can know whether the food is fresh and safe to eat.

The Imperial College London researchers who developed PEGS made the sensors by printing carbon electrodes onto a special type of paper. The materials are eco-friendly and harmless, so they don’t damage the environment and are safe to use in food packaging. The sensors, combined with a tiny electronic system, then inform nearby mobile devices, which identify and understand the data about spoilage gases.

Lead author Dr Firat Guder of Imperial’s Department of Bioengineering, said, “Although they’re designed to keep us safe, use-by dates can lead to eatable food being thrown away. They don’t always reflect its actual freshness. In fact, people often get sick from food-borne diseases due to poor storage, even when an item is within its use-by date.”

“These sensors are cheap enough so we hope to see supermarkets using them within three years. Our goal is to use PEGS in food packaging to reduce unnecessary food waste.”

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.

If your in-box is currently reporting unread messages in the hundreds or thousands, you might have a hard time believing the news: e-mail is on the decline.

At first thought, that might seem to be the case. The incoming generation, after all, doesn’t do e-mail. Oh, they might have an account. They use it only as we would use a fax machine: as a means to communicate with old-school folks like their parents or to fulfill the sign-up requirements of Web sites. They rarely check it, though.

Today’s instant electronic memos — such as texting and Facebook and Twitter messages — are more direct, more concentrated, more efficient. They go without the salutation (称呼语) and the signoff (签收); we already know the “to” and “from.” Many corporations are moving to messaging networks for exactly that reason: more signal, less noise and less time. This trend is further evidence that store-and-forward systems such as e-mail and voicemail are outdated. Instead of my leaving you a lengthy message that you pick up later, I can now send you an easily-read message that you can read — and respond to — on the go.

The coming of the mobile era is responsible for the decline of e-mail. Instant written messages bring great convince to people. They can deal with them at about any time: before a movie, in a taxi, waiting for lunch. And because these messages are very brief, they’re suitable for smart phone typing.

Does this mean e-mail is on its way to the dustbin of digital history? Not necessarily. E-mail still has certain advantages. On the other hand, tweets and texts feel ephemeral — you read them, then they’re gone, into an endless string, e-mail still feels like something you have and that you can file, search and return to later. It’s easy to imagine that it will continue to feel more appropriate for formal communications: agreements, important news, longer explanations.

So, e-mail won’t go away completely. Remember, we’ve been through a transition (过度) like this not so long ago: when e-mail was on the rise, people said that postal mail was dead. That’s not how it works. Postal mail found its smaller market, and so will e-mail. New technology rarely replaces old one completely; it just adds new alternatives.