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I agree, and I know (and like) Eric and Ralph... but this is philosopher scientists and computer scientists looking at mechanical engineering (and material scie
by kurthr 5y ago
I agree, and I know (and like) Eric and Ralph... but this is philosopher scientists and computer scientists looking at mechanical engineering (and material science) problems. Similarly, there was a lot of work at MIT on doing micro scale motors and turbines, which just work very different due to Reynolds # scaling, heat dissipation, and other issues.
Realistically, you need a demand side on this sort of work for functional and realistic solutions to take hold (iterate and improve). Right now Moore's Law has driven semiconductor logic to the point where very little else can economically compete. Thus there's little investment of resources... or even accurate determination of markets. At the same time many people view nano (and micro) machining through Moore's lens, when in reality the low dimensionality, isolation, and fault tolerance of electrical/digital solutions allows for much more design independence/flexibility and complex system development.
Imagine the vibratory harmonics of a mechanical computing system. There would be literally millions or billions of coupled oscillators. What about stiction/frictional losses due to surface chemistry/tension? What about limiting thermal noise effects? It's complicated and there's no money in it :^)
- mLuby 5y agoRalph does mention "dissipative mechanisms" but dismisses them as negligible without elaborating. https://www.youtube.com/watch?v=yVX9Ob4SjGA&t=1068s https://www.youtube.com/watch?v=yVX9Ob4SjGA&t=1068s
- kurthr 5y agoAnd you know what... I'm fine with that. You have to pick your battles and design something and try to make it work in simulation before you find the real stumbling blocks. If you can't even solve the idea problem, then you have to go back to the drawing board before you try implementation.
- kragen 5y agoHi Kurth! I never did tell you how much I appreciated you telling me about how capacitive touch sensors work on that hike. Ralph has done a bunch of work on mechanical flexure computing stuff that works entirely through vibratory harmonics, as you probably know but might not be thinking about at the moment.
- kurthr 5y agoYes, I've seen it... and it's what we don't know about such structures rather than what we know to expect (or can model easily) that will likely make/break such solutions. There is so much to do since it's such a green field, but there's very little actual implementation and the entrenched competition is soooo stiff it's hard to get funding to build something. p.s. always glad to discuss cap-sensors... a field I never thought I'd end up in.
- kragen 5y agoYeah, that's true. The potential upside is large, but the timescale for profit is too long to fund.
- Animats 5y agoIn terms of scale, digital micromirror chips for projectors have a pixel pitch around 5um. Those have a flexure, a miror, and a driver, piezoelectric or electrostatic. So that's a reasonable size for moving parts with current fab technology.
- kragen 5y agoThose are somewhat limited by optics, though. If you could make a DMD with a pixel pitch of 500 nm it would not be a useful display for visible light because of diffraction. Also, they are usually used to produce moving images for human eyes, so it isn't useful for them to run any faster than a few kHz, which macroscopic things like speaker cones and dentists' drills can already do. So it might be possible for current fab technology to make much smaller, faster moving parts than that; Zettl at Berkeley COINS reported a 500-nm-across motor in 02003, for example, but using nanotubes rather than photolithography.