Wi-Fi-connected 3D-printed objects communicate without electronics

February 13, 2018 | 11:58
Source: Computer Science & Engineering, University of Washington
Source: Computer Science & Engineering, University of Washington
With technologies of all sorts having invaded our lives in every domain it is interesting to see how new technologies are being developed that exploit existing technologies as if they were part of nature instead of man-made. Wi-Fi is a good example. Because Wi-Fi access points are everywhere navigation systems can use databases of Wi-Fi access points to accurately calculate their position. Wi-Fi access points thus have reached the status of landmarks.

Wi-Fi backscatter communication
Source: Computer Science & Engineering, University of Washington

Another emerging technology based on Wi-Fi signals is Wi-Fi backscatter communication where passive objects use the Wi-Fi signals surrounding them to send information to a receiver in a way similar to a mirror reflecting sunlight.

Since Wi-Fi signals are reflected by objects they can superimpose information on the signal by modulating their reflectivity. A receiver can detect the object and extract the information by comparing the Wi-Fi signals it receives over different paths. Without modulation all the packets should contain the same information whereas modulated reflections are different and therefore detectable.

Researchers from the University of Washington have developed 3D-printable objects capable of modulating their Wi-Fi reflectivity. Using their methods, they created smart passive objects that transmit information about their state without requiring energy or electronic parts.

By integrating a 3D-printable antenna in an object its RF reflectivity becomes controllable. Mechanical motion like a flowing fluid or pressing a button can change the object’s RF reflection properties in a controlled way, for instance by connecting and disconnecting the antenna. Like Morse code in telegraphy, a dented wheel can push a button to short the object’s antenna according to a predefined sequence. This modulates the object’s RF signal reflection in such a way that a receiver can detect it.

The researchers have printed several examples, from a self-ordering detergent container to sliders that scroll the internet page you are reading.
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