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Comment by SavantIdiot | Hacker News Reader

These devices don't even have space for an antenna (limited by physical size). The power required by the sensors is dwarfed by RF transmit.

The current challenges of powering a radio device with an MPU at this size are far too great for this to be useful. Unless there is a breakthrough in radio physics, drones need to be a certain size that is much larger than this.

Unless they plan to release a billion of these, sweep them up, and then have interns/grad students probe each one to extract the collected data.

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The whole article is massively misleading. The team used same basic design at three different scales: micro, meso, and macro (their terminology). They are 0.4mm, 2mm, 40mm in diameter respectively. The "IoT flier" used the macro scale design; in 40mm you definitely can already fit all sorts of antenna, although power is still an issue. All the other, smaller fliers did not have any microchips in them.

So the title "Flying microchips size of sand grain" is just plain wrong here :(

> Unless they plan to release a billion of these, sweep them up, and then have interns/grad students probe each one to extract the collected data.

After reading the article and watching the video, I think that's what they are aiming for. The coil can couple data and power through near-field interaction, so they'll release a large number, hope to recover a sample of them, and extract the data through field or lab instruments. I could see this being useful for recording environmental data and forensic tracing, but they look closer to RFID tags than a computing platform.

Or just, you know, use a high frequency. There are tiny antennas. You can just power it via induction (like RFID) and you're set. It still couldn't transmit super far but I bet it would work.

High frequency = high power. Energy harvesting is in the femptoWatt range.

"Frequencies from 100 GHz to 3 THz are promising bands for the next generation of wireless communication systems because of the wide swaths of unused and unexplored spectrum."

"Also, new results that give insights into power efficient beam steering algorithms".

From "Wireless Communications and Applications Above 100 GHz: Opportunities and Challenges for 6G and Beyond"

> High frequency = high power

This isn’t true in any sense applicable to this discussion. For example a near-optical laser transmitter can be as or more efficient in joules per bit than an RF transmitter, depending on the situation.

> A near-optical laser transmitter

Do you have to aim that laser transmitter?

Depends on the application, but if you do, it won’t pose a problem:

* you have more options than with RF (optics or phased array)

* you’ll get better angular precision at a given transmitter size

6G communications is being prepared to use very high frequencies.

Also, plans are to use directed energy, not classical wave like RF.

https://en.wikipedia.org/wiki/6G_(network)

Higher frequencies generally means lower range. Attenuation from atmosphere and water vapour starts to become a major issue.

Doesn't that ring-like structure in the center look like an antenna? I suppose it could just be traces between the 'lobes' of the circuit on each wing. That said, it does seem like a tall order to pack in useful sensors and some way to transmit into tiny particles like these.

The ring is a NFC coil.

All you need to transmit data is one LED.

Yes. In a nice confined lab. Now do it in daylight with millions of these things all pointing different directions.

EDIT: Unless you meant for downloading after retrieval. That could work...

With the power available and in sunlight that would be impossible. I'd put a mini mirror behind a mini old-style b&w LCD screen and use the LCD to modulate reflections on the mirror, making it purely passive except for driving the LCD, which however would draw 3 orders of magnitude less power than a LED.

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