So What About Microfactories?

I got an interesting question in my email earlier this week: with all the buzz about RepRap, is it plausible that microfactories could be developed soon, build many things cheaply, and then transition smoothly into nanofactories as the feedstock improves via nanotechnology?

The short answer is: yes and no.

Yes, because microfactories are already being developed. Open source designs such as RepRap are becoming competitive with commercial designs costing ten times as much. RepRap is designed to build (partial) copies of itself, driving down its cost. It uses inexpensive materials, and a rapidly expanding range of them.

It's possible to imagine an economically significant consumer-model rapid prototyping machine, sometime in the next 5-10 years, that can build a wide variety of products, using a variety of inexpensive solid, liquid, and melt-able inputs. It's possible to imagine that the product range will expand toward factory-manufactured quality, and meanwhile the inputs will become "smarter" as they increasingly incorporate nanotech.

But there are several reasons why a nanofactory will be better than a microfactory. There are multiple physics features that are very beneficial at the nanoscale but work less well at the micro-scale.

Perhaps the most important physics feature is operation frequency. The smaller you make something, the faster it works. The relationship is more or less linear, so a nanofactory's equipment could do a thousand times as many operations per minute as a microfactory. Combine this with the length-to-volume ratio, which means that you can fit a billion devices into the space of one by making them 1000 times smaller, and we see that a nanofactory could do a trillion times as many operations as a microfactory. (That's 10^12, or 12 orders of magnitude.)

So, while a microfactory was placing a tiny amorphous blob of plastic or droplet of ink, a nanofactory could be arranging a billion atoms into a highly functional nanoblock. Even if the microfactory were placing a pre-manufactured component, that component would not have a billion features - because nothing today can build an inexpensive device with a billion features. 

Making a late-night no-math guess about what objects might have a billion features, the first three that I thought of were the Space Shuttle, modern computer chips, and... a potato. Potatoes, of course, are made by nanotech, and they cost $1 per pound. Computer chips are made by microtech, and they cost many thousands of dollars per ounce. The Space Shuttle, of course, represents astronomical cost (no pun intended).

So it's possible that an advanced microfactory might use feedstock particles that incorporate dozens of features, and might place millions of them, and might build something with a billion features for a few hundred dollars. If this seems implausible, consider that molecules made by ordinary chemistry can have dozens of features, and an inkjet printer can print many millions of dots per minute and can print its own weight in ink in about a day. So in a sense, what I've described already exists - just not in a 3D factory version yet.

Another physics feature is that atoms are perfectly precise, and snap together with perfect precision. That's not true of microtech stuff. It might be hard to make a factory that could build duplicate factories without loss of precision out of amorphous feedstock. Of course, if the feedstock was, say, microtech structures built by lithography on million-dollar machines, then larger precise structures could be built, which might be cheap per feature, but they wouldn't be cheap per pound. (Think this is science fiction? Zyvex has been doing snap-together MEMS for years.)

It would be great, of course, if a microfactory could include enough lots of microtech fabrication systems, each system having been built by a microfactory. At that point, the feature count of products could go through the roof, at least by today's standards. I can think of a few possible approaches to try, but nothing that I'm sure would work, and nothing that could be developed quickly.

When I started writing this post, I was expecting to demonstrate that a microfactory couldn't work well enough - that its products would be so non-revolutionary, thanks to the less-cool physics at the microscale, that it wouldn't be worth engineering or selling. But the more I think about it, the more I start to suspect that there may be some interesting designs lurking somewhere in the design space. They'd be pretty different from today's gantry-crane melted-plastic fabbers, but that's an engineering challenge, not a criticism.

Chris Phoenix

Comments

[jim moore]

I have been thinking "If i had a home faber what would I really want to fab on a daily basis?"

Clothing.

I have been able to (in theory) get rid of my books, my records, my video tapes which is freeing up a lot of space in my house. Next on the list is the whole dresser / closet - washer / drier and ton of clothing that is in my house. I would like to replace it with a home fiber faber - the clothing would fit my current dimensions, with no seams. Every night I toss the clothing into the recycler, put on my pajamas and pic out what I am using tomorrow. The stuff gets put together overnight and is ready the next day.

It would be a parents dream - no laundry - no storing away winter or summer cloths - no constant shopping to get the kids outfits that fit or school uniforms or sports outfits, - no added expense to keep up with holidays and fashion.

Still a Fiber Faber would be pretty impressive - it would need to handle different colors, different fibers, different styles, different thickness to the clothing and be able to clean, sort and store fibers from the used clothing.

From a nanotech perspective even a very thin fiber has a great deal of design space. (Fibers ~10 microns in diameter and ~10,000 microns long) So there is a huge potential to add functions to fibers over the long run - computing - communications - sensors - actuators - light emitters - energy storage. It possible to envision this as a pathway for incresingly tiny devices get integrated into daily life. (admittedly its not the most obvious pathway, although clothing was critical to the first industrial revolution)

[mark o'leary]

Thanks for responding to my question, and I'm glad you see glimmers of possibility in this space. I probably shouldnt have mentioned reprap, as I dont see microfactories necessarily being a design continuum from reprap, although what the reprap initiative does underline is that a microfactory designer may have to take an ugly piecemeal approach, for example, component types may come in different scales and tolerances; there may be subtractive as well as additive steps in the build process, etc.

I see this as much like engineering today, component/tolerances matching the subproblem at hand. After all a nm precision chip mfrg plant starts with cm precision bricks at its outer walls. For example, I imagine a microfactory would replicate in a sequence of less refined steps, such that the smallest/highest tolerance child parts are built/tested first, and the low tolerance outer scaffolding last - and probably some manual assembly still required, as for reprap.

[mark o'leary]

(cont...) On the other hand, I think that microfactories could be directly on the path to nanofactories, as nanoscale components gradually become available for advanced microfactories - perhaps the first nanofactory will be a microfactory with an onboard but very limited "nanoforge" subsystem.

My gut feeling is that there certainly is a market for microfactories as the technology, even if initially expensive, could serve a multitude of niche markets and the costs would rapidly drop. I think it would be more productive to push a microfactory vision (entirely plausible) harder than the nanofactory vision (perceived as sci fi). The nanofactory vision would be obvious and less controversial down the track.