Scientists at the University of Washington have engineered something that defies belief: inexpensive plastic contraptions that, despite containing no electronics or electricity, act like sensors and connect to Wi-Fi devices like your smartphone. It’s something that “no one has been able to do before,” according to Vikram Iyer, a University of Washington doctoral student and coauthor of a paper on the research.
So how the hell does this dark magic work? The answer lies in three design details: the type of plastic they use, ambient Wi-Fi radio signals, and rudimentary mechanical gears and springs.
At the heart of each prototype sits a 3D-printed conductive antenna made of plastic mixed with copper. This antenna is sensitive to the Wi-Fi radio signals that continuously travel through space, which means it can affect that signal by reflecting or absorbing it. Right over the antenna is a switch made of the same material, which is connected to a spring and moved by a gear. The gear is connected to other contraptions–like a mechanical scale in the case of the laundry soap bottle–and will move whenever something happens.
When that gear moves, the switch closes and opens the circuit rapidly–a little like a Morse radio transmitter–sending 0s and 1s into the Wi-Fi network. That binary information can then be detected by your smartphone or any other wireless device connected to that Wi-Fi router. According to the researchers’ paper, they demonstrated the potential of this technique with the first-ever “fully 3D-printed wireless sensors including a weight scale, flow sensor, and anemometer that can transmit sensor data” without the use of batteries or electronics.
Their weight scale could be incorporated into all kinds of packaging to detect when you’re running out of a product, like laundry soap or cornflakes. A flow sensor attached to the bottom of a sink would be able to tell you when there’s a leak. And the anemometer (which measures wind speed)? Well, the anemometer is just fun. But all three are just examples. Nearly any object that can activate a simple mechanism could serve as a source of motion for these electricity-free transmitters.
The plastic modules are also so cheap to produce that they open up the possibility of a world in which any laundry soap bottle, a coffee can, or a water pipe could instantly connect to the internet to relay useful information and trigger any number of actions. “A lot of things we use today are made of plastic–including the canonical detergent bottle!” senior author and associate professor at the Paul Allen School of CSE Shyam Gollakota writes to me over email. “[We] can enable Wi-Fi connectivity for anything.”
So, when will your bottle of Tide be capable of automatically ordering you a refill? Gollakota says they’re still improving on the data rate and the reliability, “so hopefully in a few years.” Until then, you can try these plastic thingamajigs yourself if you have a 3D printer–the inventors have made the CAD models available here.