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These Plastic Objects Can Talk to Computers Without Electronics or Batteries

The natural assumption is that for a device to wirelessly communicate with another, it needs some basic electronics inside and a source of power. But researchers from the University of Washington have seemingly done the impossible by creating simple plastic devices without batteries, chips, or even wires that can still interact with smartphones and computers.

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The research, conducted at the University of Washington’s Paul G. Allen School of Computer Science & Engineering, further simplifies Internet of Things devices by building on previous research from a few years back that involved harnessing a technique called backscattering to hijack FM radio signals to broadcast alternate messages.

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By upgrading a simple poster with an antenna made from thin copper tape and electronics powered by a small coin battery, the researchers working on the FM project were able to introduce new audio signals by reflecting and modifying more powerful signals from an FM radio station. The new signals existed in a nearby but unused part of the spectrum, so anyone nearby with a radio could tune in to what was being broadcast by the poster, as well as the original FM signal. The low power consumption meant the poster could keep broadcasting for years, as long as the more powerful FM station was still in operation. 

This new research takes that idea even farther.

Instead of manipulating signals from a powerful FM radio tower, this new research focuses its efforts on wifi networks which, at this point, are in almost every household and place of business. The simple devices, which include everything from buttons, to sliders, to even more complex contraptions like a wind-speed measuring anemometer, are created using an off-the-shelf 3D printer and readily available filament, although specific components are made from a filament that’s been embedded with copper or graphene filings giving it electrical conductive properties allowing it to act as an antenna.

In the case of the plastic anemometer, the wind turns a plastic gear that works alongside a coil spring to intermittently activate and deactivate an antenna that absorbs or reflects a wifi signal, producing a new signal that can be decoded like a binary message by another device. A mechanism can be specifically designed to control and regulate the number of wifi reflections occurring, and software can be developed on the receiving end to make sense of what otherwise looks like noise.

Other examples the researchers 3D-printed and demonstrated included simple buttons, scroll wheels, and sliders that, in real-time, can control the behavior of a nearby smartphone or computer by simply reflecting wireless signals that are already bouncing around a room. One of the bigger challenges of the Internet Of Things (aside from distressing security concerns) is that even simple devices still need a source of power, adding to the long list of devices in your home that need occasional charging or battery swaps. This approach takes the need for power out of the equation entirely by piggybacking on a technology that most of us already obsessively ensure is always running in our homes.

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DISCUSSION

Could you not do the same thing with acoustics?  Mic on the PC listens for specific patterns in ambient audio, like a specific frequency or tap pattern, and activates whatever.  A printed button that clicks a certain way could then turn on a device, etc.