If I understand this correctly, this is a paper about 3D printing physical objects, with no electronics, that send information over wifi.

ie, magic.

This is magic.


@ajroach42 not really sending information over wifi (backscattering, producing radio signal that doesn't really have anything to do with wifi), but yeah, magic.
I'm curious how well it works, and what is involved on the receiver end (haven't read the paper yet)


According to the video, the goal is for the backscattered signal to interact with wifi receivers, unless I'm misunderstanding something.

@ajroach42 @Thib In the first few pages, I see no reference to "wifi receivers". They very carefully always say "RF receivers including WiFi".

@kurtm @Thib

At some point, the difference between a "wifi receiver" and "RF receivers, including wifi" is splitting hairs, yeah?

Like, I understand that wifi is a specific protocol that uses a spectrum shared by lots of other devices, and that without the ability to generate more complex signals it won't actually be "wifi" but if a standard wifi radio can receive these signals and be made to understand them, wants the point of the pedantry?

@ajroach42 @kurtm the thing is, it will only fall in the same range of frequencies as WiFi, but the modulation has nothing in common and it will completely ignore the protocol. So it's far from obvious how WiFi receivers could handle it.

@ajroach42 @Thib There is no comma. It looks like they are talking about boxes that collect signals from these things and pass that on to Wifi. Like a bridge.

If I get a box talking RS232 to a host with wifi, I can claim it talks to "signal receivers including wifi". It's not speaking wifi. The host is speaking wifi. Using that specific awkward wording was a big tell to me.

I mean, it's very cool stuff, but it's not things without electronics speaking wifi.

@kurtm @Thib

I haven't read the paper yet, so I can't speak to the specifics beyond what they included in the web page and their powerpoint.

The website says "Our goal is to 3D print wireless sensors, input widgets and objects that can communicate with smartphones and other Wi-Fi devices, without the need for batteries or electronics."

@Thib @kurtm

Now, based on my understanding of how wifi works, they would need direct control of the radio, and to write a custom driver in order for the data their devices produce to be readable by a smartphone.

It wouldn't technically happen over wifi, but to an end user the difference wouldn't matter.

@kurtm @Thib In the situation you're describing, there is a receiver other than the smartphone sitting between the device producing the signal and the wifi receiver that would receive and interpret the signal, and send the results out over wifi.

At some point, I'll actually read the paper and verify.

The neat thing here is that they are generating the signal without electronic components or electricity.

3D printing a sensor that can passively communicate is a big deal.

@Thib @kurtm
I skimmed the paper for the section that deals with the wifi receiver, and it looks like basically we were both wrong.

There's a wifi transmitter, and wifi receiver, and between them, the sensor.

The sensor modulates the wifi signal passing between the wifi devices.

The differences between the unmodulated signal and the modulated signal are decoded by a device at the receiving end.

They go in to the details in section 3.2 of the paper.

@ajroach42 @kurtm quickly went through that section of the paper, pretty much what I expected. They do use existing WiFi hardware for decoding signals, though. That's pretty impressive.

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