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Fluidics (wikipedia.org)
37 points by wglb on May 25, 2018 | hide | past | favorite | 14 comments

"Fluidics, or fluidic logic, is the use of a fluid to perform analog or digital operations similar to those performed with electronics."

Not sure why this is on the front page of HN. I find it mildly interesting, but it's a wikipedia page and there's no relevance to recent facts or discussions.

Anybody could help me understand?

There was a post about a hydraulic computer here the other day, this looks like further reading. Interestingly, there seems to be a slow increase in intrest for ionotronics where logic is implemented using nanopores in salt water, where current is carried by ions instead of electrons. Generally the propogation delay is orders of magnitude longer than in electronic circuits, but the parallel between fluidic computation and biological processing (as in brains) is compelling. I was able to put together a few gates and oscillating electrofluidic circuits using electrically addressable nanopores in my PhD work, but others have more recently made complete circuits.

It's probably a follow-on posted in reaction to this other recent HN story that got a lot of points: https://news.ycombinator.com/item?id=17140039 ... "Computing Partial Differential Equations with Water".

There was an article on performing diff eq with water. Presumably someone felt like sharing this in response.

I wonder if something like this [0] (looks like moving liquids without pumps or power) would be possible to miniaturize this idea further? (maybe smaller amounts of electricity like in the brain combined with this kind of tech)

The stuff I have seen tends to be large on a scale reminiscent of the very first computers. (ie, large mechanical switches powered by solenoids or spinning gears)

[0] http://www.surnetics.com/

To be fair, miniaturization never has been a problem in the electronics industry evolution. Nowadays you can have more than 4,000,000,000 transistors in a 10nm chip and the lithographic process advances to produce these chips tend to evolve into even further miniaturization and more transistors.

Pretty sure this project is dead: http://groups.csail.mit.edu/cag/biostream/

But it has some pretty neat examples, not doing computation, but a programmable system for moving, storing, and mixing samples.

Modern electronics have an effective limit of ~100 deg Celsius, which makes them unsuitable for some uses.

Fluidics are order of magnitude slower and larger, but proper material selection can make them withstand very high temperatures.

Fluidics have actually found useful applications at extreme temperatures. Fluidic capillary pyrometers have been used to measure the temperature of molten steel and here is an image of a fluidic afterburner fuel control operating at temperature's so hot it's glowing[0]

[0]https://imgur.com/uwPSpR5 from Fluidics Quarterly Volume 4 Number 2, page 54

Fluidics was a technology that was invented at the wrong time. It was invented in the 1960s just as transistorized computers were becoming common. One can only speculate on what the world would be like if fluidics was discovered say in the 1800s. It could potentially be mass produced with technology of the time. Right off the bat one might be able to attain switching speeds similar to relay computers for complicated circuits, audio-frequency operation for simple circuits, and analog computation at decent speeds. So we can get things like adding machines, somewhat automated factories, autopilots, sound amplifiers, gunnery computers, and what not. Of course, this alternate history is unlikely, because some of the knowledge necessary to develop fluidics came out of understanding airplane flight. The coanda effect, wherein a jet of fluid tends to stay near walls which is useful for making bistable flip flops, was discovered accidentally when testing a new airplane design[0]

Even though fluidics came out at the wrong time it did find some niche applications in aerospace and factory process control because fluidics was more reliable than similar electrical and electromechanical systems for a bit. Fluidics not having any moving parts is fairly robust and is tolerant of high temperatures, high shocks, high radiation, high magnetic fields, and more. The concorde actually used fluidic components in one of it's nozzle control systems at one point[1].

Because of fluidics inherent EMP resistance and acceleration resistance, fluidics has been considered shockingly recently for use in anti-ballistic missile guidance systems[2].

Fluidics still enjoys some niche applications today. Some HVAC and industrial control systems supposedly use fluidics. One interesting current day application of fluidics is kosher sound amplification[3]. Orthodox Judaism prohibits electronic sound amplification on the sabbath because it constitutes work. Using a speaker to produce sound constitutes labor because it creates a sound that did not exist before from electricity. Fluidics is able to get around this prohibition and can amplify sound in the range of human speech.

[0]http://www.thermofluids.co.uk/effect.php [1]http://www.dtic.mil/dtic/tr/fulltext/u2/a049256.pdf [2]http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDo... [3]http://acoustics.org/pressroom/httpdocs/132nd/2aaa8.html

I wonder if side-channel attacks are possible on fluidics.

Sure. Any incidental effect related to the actual physics used to encode information potentially could leak information. Fluid has mass, and accelerations require forces, so acoustic, acceleration, and thermal side channels are all a possibility.

Absolutely. In order for fluidic devices to function you have to vent fluid to ground. For pneumatic devices this is typically the surrounding air. This should produce an acoustic signal that can be detected. However, one could operate such a system in a closed loop manner to prevent this where in all the ground vents feed back into the pump supplying the circuits. However, there are still likely to be load variations that could be detected.

That is awesome. Thanks!

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