Something weird to deck the Xmas tree with: 3D-printed Wi-Fi baubles

In an effort to make objects more chatty, boffins at the University of Washington have developed a way to create 3D-printed plastic baubles that can communicate over Wi-Fi with other devices, without batteries or electronics.

The technique, developed by UW doctoral students Vikram Iyer and Justin Chan, in conjunction with UW associate professor Shyam Gollakota, involves embedding plastic materials with metallic threads so they reflect Wi-Fi signals.

"We realized we can't 3D print a Wi-Fi chip or electronics on 3D printers today," said Chan in a phone interview with The Register. "But we can print 3D objects with conductive filaments."

The embedded copper and graphene in the objects reflects Wi-Fi signals, creating signal backscatter that can be detected by smartphones or other Wi-Fi-enabled devices.

Iyer likened the process to signaling with a bright light and rotating mirror that can modulate the message into on or off states. "We have these devices that can actually reflect the Wi-Fi signal away or toward the source," he said.

As a proof of concept, the researchers made a flow meter that can be fitted to the spout of a detergent bottle to transmit the detergent pour-rate, which indicates the need for a refill at a certain threshold.

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Chan said the attachment could be used to reorder more detergent, like an Amazon's Dash button. "But it's almost one step further," he said, "because Amazon's button cannot detect when the detergent is running low."

To transmit specific information, like a product identification code, the researchers designed a gear to encode the data into bits, with the presence or absence of a gear tooth representing a 1 or a 0.

The power for transmission comes either from physical motion – liquid passing through a flow meter, force on a 3D printed button, knob, or slider – or from fabricated sensors capable of harvesting ambient backscatter energy through their operation.

Backscatter power, however, isn't all that useful beyond sending short identifiers. The researchers only managed to transmit data at bitrates up to 45bps in this manner.

In addition to printed Wi-Fi, the researchers developed a method of magnetically encoding information in 3D printed objects. This data can then be read by a smartphone using the onboard magnetometer that assists with navigation. Think of it as RFID but with a commodity smartphone rather than a more costly RFID reader.

The computer scientists used a consumer-grade 3D printer, the MakeiT Pro-M. The switches and antenna for the project were created with Electrifi's conductive copper filament; ferromagnetic portions of models – where magnetic information can be encoded – were produced with ProtoPasta's magnetic iron filament.

Iyer said at present this is an academic project and that the prototype designs have been released for people to play with. No plans have been made to commercialize the work, but the researchers are considering what to do next. ®