Electronic labels printed by inkjet

Imagine waving your smartphone over your shopping basket and the oranges telling you when and where they were picked, the pills in your doctor's prescription confirming that they are in-date, and even the bank notes you'll use to pay for the shopping authenting themselves.

This is now all feasible thanks to a Swedish and UK breakthrough that means it's possible to print electronic circuits onto paper labels. They're called E Labels and they can be powered by the radio transmissions from a mobile phone. It's a development of electronic chips called Radio Frequency Identification Tags, as science writer Mark Peplow explained to Chris Smith...

Mark - We've all heard about radio frequency identification tags known as RFIDs they've become ubiquitous over the past decade. They're used to track goods, contactless payment cards like Oyster cards in London. They're used in passports and loads more.

Chris - How do they actually work, Mark?

Mark - You can either have a passive RFID tag which basically picks up a radio signal and uses that to generate a current inside the device, and that current then is used to send a signal back to a receiver, and it sends some information, "I'm a load of cargo that started off in Singapore a week ago, and this is where I've been sent." Other ones are actually powered by batteries and they tend to be able to send signals over longer distances and carry more information as well, but they're a lot more expensive.

People have been trying to create much cheaper tags which they call eLabels that can be printed onto any surface using just an inkjet printer. And now, a team in Sweden has created the first printed eLabel that can communicate directly with a smartphone.

Chris - So, this is intriguing. You can actually print a circuit with ink.

Mark - Yeah, that's right. Essentially, a diode is what they're printing and that's built up using tiny particles of silicon locked into a sort of polymer slurry and you can print it out using an inkjet printer. You hook that diode up to an aluminium foil antenna and a flexible polymer display, and when you wave a smartphone over this device, the high frequency radio signals from the smartphone are picked up by the antenna, channelled into the diode, and that moves electrons around in the diode and generates a current. That's used to illuminate the polymer display. So, the smart phone signal is being used as an energy source. Now, this is a proof of principle. In the future, the researchers say it should be quite possible to use that energy to send a signal back, carrying information back to the smartphone so that you're passing on details about whatever this eLabel is stuck to.

Chris - Wow! So, you could for instance print a bank note and print into a bank note some circuit similar to this and this would mean that if someone wanted to say, authenticate a bank note to prove it wasn't a forgery, you could just wave your phone over it. The energy just from the phone radio waves coming out of the phone would drive this.

Mark - That's exactly right and that's actually why this team started working on this. They were working with a British company called Delarue which is the world's largest bank note and passport manufacturer. They wanted to make a security code that could be printed into bank notes. In theory, yes, a smartphone held close to this bank note would be able to identify the eLabel in it, and that might hold information about the origin of the note, how long it's been in circulation, and so on, and that should be very difficult to counterfeit.

Chris - This is almost like a fusion between cash and card or electronic transactions. You've actually got money with a memory, potentially.

Mark - Potential for this goes a lot larger. The researchers are saying that this is a key component - this diode - in what you would need to actually build an internet of things. Now, this is a concept that's been talked about for a few years that will basically see pretty much everything connected to the internet. You can sort of see why connecting your fridge to the internet might be useful. It could monitor when you need to order more food from the supermarket for example and just do that automatically for you. But what about connecting paper magazines to the internet, or an orange? I mean, if you have an eLabel stuck to an orange, you swipe your phone over it and it tells you where it was picked, how long it took to transport it from wherever it was picked. So, the idea is that you can achieve these sorts of things if you can get cheap enough eLabels to do this. That's what this printing technology allows you to do because it literally is just inkjet printed onto a surface.