
Additively manufacturable micro-mechanical logic gates - bobajeff
https://www.nature.com/articles/s41467-019-08678-0
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tndl
3D printed mechanical logic gates 100um in size, compute speeds in Mhz, and
power consumption that approaches 0. Pretty cool.

~~~
genericone
0 consumption at idle. Have to put in some good old fashioned
Work=Force*Distance when you perform an operation though.

Also, how many toggles can each gate go through before material fatigue causes
the logic to get stuck? Some interesting questions which would need answering
before it can be utilized by any industry.

~~~
6nf
Flexures can last forever if you stay within the plastic deformation range for
that material. These can fail from other things though, e.g. mechanical shock,
thermal extremes, stuff like that.

~~~
tedsanders
I'm skeptical of this claim. Can you expand on your answer that there are
materials that can be cycled infinitely in the plastic regime, or point to
some sources that explain further?

I did a PhD in a materials science lab, and my understanding is that at least
for metals, you still eventually run into fatigue & failure, even if you stay
within the elastic regime (which nominally appears reversible). I'm not sure
why plastic deformation would be any better, given that you'll have atom
positions shifting and (if crystalline) dislocations propagating. I'm not a
fatigue expert by any means, so I'd love to learn more.

On the Wikipedia page for fatigue limit[1], I see a link to a reference that
says there are no metallic materials that can be infinitely cycled[2]. Is the
bonding somehow different in this 3D printed material that causes fatigue to
work differently?

[1]
[https://en.wikipedia.org/wiki/Fatigue_limit](https://en.wikipedia.org/wiki/Fatigue_limit)

[2]
[https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1460-2695....](https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1460-2695.1999.00183.x)

~~~
kurthr
One of the graduate students I worked with studied the TI micro-mirrors used
in DLP projectors. They were designed in the first round of micromachined
devices so by EEs rather than MEs, and as a result they used aluminim.

So the question to answer is, "how does a multi-million pixel display unit
array of doubly supported tortional Al hinges going through >1% strain survive
for 1000s of hours (much longer than the bulbs) oscillating at 100s of kHz".
That's ~10^12 cycles each with ppm defect rates!

Since you know that this far exceeds any reasonable fatigue strain and the
defect density /dislocation propagation should be huge! The key is that the
aluminum is <1um thick a few um wide and <100um long. The majority if the
strain is concentrated at the supported ends, but it's so thin that the whole
high strain region is single crystal!

TI didn't originally know why it worked... just that it did.

I won't say mechanical gates are a great idea... and at 1MHz they might start
failing after a few continuous months. The truly unfortunate part is that the
manufacturing processes aren't really designed to control for the grain
structure... they're designed for etch repeatability and conduction stability
so yield could fall apart while tour processes seem nominal.

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bassman9000
_A key benefit of the proposed approach is that such systems can be additively
fabricated as embedded parts of microarchitected metamaterials that are
capable of interacting mechanically with their surrounding environment while
processing and storing digital data internally without requiring electric
power._

The Diamond Age is upon us.

~~~
agumonkey
scifi reference ?

ps: indeed
[https://en.wikipedia.org/wiki/The_Diamond_Age](https://en.wikipedia.org/wiki/The_Diamond_Age)

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_Microft
Mechanical circuits could be a low performance replacement for electronics in
environments where the latter fail, e.g. because of high temperatures or
radiation.

I think I remember something about an idea for a mechanical communications
system for a Venus lander that worked by wheels that increased or decreased
radar reflections so data could be read from orbit by bouncing a radar signal
off it.

Maybe combine stuff like this?

 _Edit: adding link:[https://www.theengineer.co.uk/mechanical-rover-explore-
venus...](https://www.theengineer.co.uk/mechanical-rover-explore-venus/) ._

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travisoneill1
> As a result, such devices generate no electromagnetic signature and are
> highly insensitive to radiation damage.

Sounds like this would be ideal for use in spacecraft.

~~~
3chelon
Buy one now. After the Solar Flare Apocalypse, those of us rocking mechanical
computers will be control the world!

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bitwize
This is Young Lady's Illustrated Primer stuff. The future just became a
slightly cooler place to be. I am so stoked.

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nimish
NEM relays have these beat in size, at least: [https://nems.stanford.edu/nem-
relays](https://nems.stanford.edu/nem-relays)

~~~
azernik
Those are electromechanical - they use mechanical changes to open and close
electrical pathways. These are purely mechanical.

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dfox
Exactly why is it important that this particular structure can be additively
manufactured? Typical additive processes can create essentially anything,
exactly because there are no limitations steming from tooling geometry and
workholding that are typical for traditional subtractive machining.

~~~
samplatt
Speaking as Stephenson/Doctorow fan as well as a member of ever-growing sector
of the population that have had their technological paranoia continually
proven right for the last fifteen years, improvements in additive
manufacturing of miniaturised computation technology assists in keeping a
small section of power with the larger population, rather than being forced to
rely on hyperlarge gated conglomerates to parcel out materials to us.

~~~
blotter_paper
I don't know why this is being down-voted. Anyone care to elaborate? If we
don't want to rely on centralised manufacturing we need to be able to make
computers in the privacy of our own homes. Otherwise, whoever controls the
entities that manufacture our computers can put in backdoors. The government
has straight-up said that they want backdoors into all encryption. Worrying
about this, and making progress towards decentralised manufacture, doesn't
seem crazy to me.

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segfaultbuserr
Does anyone on HN can explain this question to me: is there a real obstacle
that prevents one to build a general-purpose digital computer using pure
macroscopic mechanical components? Historically, we had several types of
special-purpose mechanical computers, but a general-purpose mechanical
computer was never built.

Was it because the mechanical parts are too prohibitively
rigid/inflexible/heavy/expensive for a computer? Or, a real barrier for
mechanical computers doesn't really exist, and we didn't have it simply
because it was not economically worthwhile to build one after electronic
computers were feasible?

~~~
adrianN
You might want to read up on
[https://en.wikipedia.org/wiki/Analytical_Engine](https://en.wikipedia.org/wiki/Analytical_Engine)
There is good reason to believe that it can actually be built, and a simpler
design that is not general-purpose is exhibited in the Science Museum in
London.

~~~
segfaultbuserr
Thanks, I confused Differential Engine and Analytical Engine, and believed the
latter was a more much powerful version, but still not general-purpose. But
apparently Analytical Engine is Turing-complete.

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galaxyLogic
How do you program it? Would the programs have to be mechanically constructed
as well?

~~~
yetihehe
Like all logic chips today, with a standalone programmer. You make program on
your desk computer then send it to chip. Electronic-mechanical converter would
setup your device.

Without computer you could do it old-way with a panel of switchable bits and
clock signal. You enter required bits with user-switchable levers, then switch
clock lever up and down, then enter another machine-word. Or make your program
on punch cards.

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dmolony
I hope they build a Difference Engine or Analytical Engine as a proof of
concept.

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PaulHoule
These look a lot like the system proposed by Drexler back in the 80's!

~~~
abecedarius
More like Merkle's buckled-spring logic, at first glance. Merkle was building
on Drexler, though.

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FullyFunctional
Really interesting. Alas, the "Supplementary Movie 1" appears corrupted for me
(tried two devices, two networks).

~~~
potiuper
[https://bugzilla.mozilla.org/show_bug.cgi?id=1368063](https://bugzilla.mozilla.org/show_bug.cgi?id=1368063)

soln: save movie file & open using video player

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kwhitefoot
Sounds like Ken Macleod's babbages. See The Cassini Division, etc.

