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Comment by azeemba | Hacker News Reader

Anyone know what is the smallest man-made powered device capable of mechanical movement?

I assume we can make mm-scale things. Considering that this 20um item is in the news and isn't powered, maybe mm scale is where the current limit is?

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I've designed a device that utilizes mechanical force to transmit information that was around 5nm in diameter. It was based on the human Notch receptor. It's a few hundred amino acids in length, folded to produce a protein that senses force transmission, is cleaved upon unfolding, and releases a transcription factor the nucleus of a cell.

I kind of find the distinction of 'robots' vs cells funny, as once you get down to the (sub)nanometer level one's intuition should flip: organic material acts stiffer and more lego-like than metals - which act more like unreliable putties. A "device" that becomes small enough is much more likely to be made of organic molecules than metallic molecules - cells ARE those futuristic robots...

The kinesin motor proteins are pretty cool too [1], but those are naturally occurring machines that I suspect we'll be imitating for a long time.

[1] https://www.youtube.com/watch?v=y-uuk4Pr2i8

It turns out the real nanotechnology was the life we found along the way.

More seriously, I think that biology is better described and studied as applied nanotechnology. These are nano-scale, complex mechanical systems that are capable of manipulating their environment in an autonomous fashion. They're the science fiction nanobots we've been looking for all along!

MEMS can have elements as small as 1um. Molecular robotics operates at much smaller scales. But generally, the line between what is mechanical and what isn't becomes the blurrier the smaller the scale is.

If you mean smallest robot with an onboard power supply and control, mm is the best we can do. The problem is that the power conversion electronics are too large. Electromagnets don't work well as you scale down. So you need piezoelectric/electrostatic actuators which need high voltage. Converting low battery voltage up is difficult without electrical transformers.

People made devices where a single atom can be moved at will.

But they are fixed.

And the smallest that fly for 1h under command?

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