An Electronic Tag You Activate With A Phone Call

The tag actually powers itself by harvesting cellphone signals.

A Printable Electronic Tag

From "All-printed diode operating at 1.6 GHz" by Negar Sani et al., PNAS, 2014

Bzzz bzzz! Who are researchers calling in this video? It's not a person. It's a thin little electronic tag. The call activates the tag's display, which then shows some graphics. The tag's makers think it's the first all-printed electronic label that's able to communicate directly with a cellphone.

Several research groups are working on making electronic tags like this. Researchers hope that in the future, tags equipped with sensors would send data about what they sense to the cloud.

For now, however, electronic tags like this are still in their earliest stages of development. This new tag, developed by researchers in Sweden and the U.K., doesn't do much more than turn on. It's slow to respond—it takes about 10 seconds—and it practically needs to touch a cellphone to do just that. Still, the tag has a couple of impressive features. It's durable, lasting for more than two years, the researchers reported in a paper published today in the Proceedings of the National Academy of Sciences. In addition, while it's always a challenge to power small electronics with equally small batteries, this tag has a unique solution for that problem. The tag actually captures a portion of nearby cellphone signals and powers its display with that signal.

The tag is made of plastic, with a printed aluminum-foil antenna and a special diode that the U.K.-Swedish researchers developed. The antenna picks up standard, Global System for Mobile signals cellphones produce when they make a call. The diode converts that signal to DC voltage. The voltage then goes to an experimental display, called an electrochromatic display, that requires little power. The lab that made the tag pioneered electrochromatic displays, too.