You’ve probably heard of the Internet of Things, in which smart devices communicate with each other to make our lives better in various ways. Generally, complex electronics are involved, so it seems impossible to have WiFi-connected devices that involve no electronics at all – just plastic. But researchers at the University of Washington have created exactly that. They 3D printed several plastic objects capable of communicating wirelessly on their own, through nothing more than expert engineering.
“Our goal was to create something that just comes out of your 3-D printer at home and can send useful information to other devices,” said electrical engineering doctoral student Vikram Iyer. “But the big challenge is how do you communicate wirelessly with WiFi using only plastic? That’s something that no one has been able to do before.”
How indeed? The researchers used what are called backscatter techniques, which use an antenna to transmit data by reflecting radio signals generated by a WiFi modem or router, for example. Information contained in those reflected signals can then be decoded by a WiFi receiver. The antenna in this instance came in the form of a conductive copper filament embedded in a 3D printed object. A physical movement, such as pressing a button or turning a knob, or something like the flow of laundry soap out of a bottle, triggers gears and springs in the 3D printed object that cause a conductive switch to intermittently connect and disconnect with the antenna, changing its reflective state.
Information in the form of ones and zeros is encoded by the presence or absence of a tooth on a gear, which is driven by a coiled spring. The pattern and width of the gear teeth control how long the conductive switch is in contact with the antenna, which creates patterns of signals that can be picked up and decoded by a WiFi receiver.
“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. The interaction between the 3-D printed switch and antenna wirelessly transmits that data,” said Shyam Gollakota, an associate professor in the Paul G. Allen School of Computer Science & Engineering. “Then the receiver can track how much detergent you have left and when it dips below a certain amount, it can automatically send a message to your Amazon app to order more.”
The researchers 3D printed a wind meter, a water meter and a scale, plus a flow meter that was able to measure detergent as described by Gollakota. They also 3D printed a test tube holder that could help manage inventory or measure the amount of liquid in each test tube, as well as a series of buttons, knobs and sliders that can be customized to communicate with other smart objects.
The researchers also used an iron filament to create magnetic properties and embed information into objects, which could include barcodes or information that tells a robot how to interact with the objects.
“It looks like a regular 3-D printed object but there’s invisible information inside that can be read with your smartphone,” said Allen School doctoral student Justin Chan.
The research is described in a paper entitled “3D Printing Wireless Connected Objects,” which you can read here.
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[Source: University of Washington / Images: Mark Stone/UW]