These 3D-Printed Plastic Objects Can Use WiFi Without Any Electronics

Smart team makes smart objects. Mark Stone/UW

Have you ever gone through the harrowing experience of going to grab some milk, wanting to know how much was left in the carton, but suddenly becoming unable to summon the energy to physically check for yourself? Well, now you’re in luck: the University of Washington (UW) has invented a process in which 3D-printed objects connect to your WiFi – without the aid of conventional electronics – in order to give you such updates automatically.

Don’t get us wrong: the technology is extremely cool. The fact is that this proof-of-concept study could pave the way for a huge range of smart devices, such as “powerless” detectors that register gas or water leaks in your house and alert you instantaneously.

The UW team aren’t the first to come up with these sorts of self-reliant devices. Back in 2015, for example, a separate team developed a tiny, $0.20 temperature sensor that didn’t require a battery or constant source of wired electricity. 3D printing isn't new either, and already, researchers can print out human organs using biological "ink".

The UW team are, however, the first to combine both in this rather clever way.

One of the 3D-printed analog gears. The way they move, and the pace at which they move, encodes digital data using nothing but analog motion. Mark Stone/UW

Presenting their paper at the cacophonously named Association for Computing Machinery’s SIGGRAPH Conference and Exhibition on Computer Graphics and Interactive Techniques in Asia, the team also showcased one of their inventions: a 3D-printed laundry soap box that keeps an eye on its volume and orders more when it’s running down.

Without any power source to worry about, these devices are decidedly eco-friendly, and very cheap to manufacture.

What technological sorcery is this, you may be wondering? Well, think about analog watches. They keep time thanks to a mechanical architecture that siphons off kinetic energy from you moving about, and stores it over time. The team wondered if they could borrow principles like this in their own marvelous project.

They guessed right. In this case, they looked into a phenomenon named ambient backscatter. This is a low-power communications technology that utilizes radio frequency signals, like those being emitted by WiFi devices, as a power source.

This little quirk of physics means that anything with an antenna can convert radio signals into small, but not insignificant, currents. That way, they can activate and run without the use of any batteries or electronics to speak of.

The UW team of engineers employed this in their endeavor, and 3D printed objects that mixed plastic with copper. So that’s the conductive antenna sorted, but how does the device know when something’s changed within it, or in the surrounding environment if it’s not always “on”?

Remarkably, much like those aforementioned watches, the objects included small gears that moved about whenever provoked by a physical motion – say, the laundry soap exiting the container – which causes mechanical teeth to click into place at various rates, and register how much or how little is left.

“As you pour detergent out of a Tide bottle, for instance, the speed at which the gears are turning tells you how much soap is flowing out,” senior author Shyam Gollakota, an associate professor in the Paul G. Allen School of Computer Science & Engineering at UW, said in a statement.

At a certain point, an electrically conductive switch will poke the antenna, forming a larger circuit. This will change how the antenna reflects radio frequency signals, allowing the WiFi router to continuously track the state of whatever the device is monitoring.

The laundry soap device is the team's piece de resistance right now, but we’d expect them to manufacture a few more technological wonders sooner rather than later, given their obvious zeal.

Their magnum opus, for now. Mark Stone/UW



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