Molecular Manufacturing: Not Just Rapid Prototyping

(This is an expansion of some comments I made in a recent thread. --Chris)

Rapid prototyping machines keep getting better. There are even some projects such as RepRap aimed at making manufacturing systems that can make more manufacturing systems. RepRap is already working on hardware. So why do we think molecular manufacturing will be revolutionary compared to rapid prototyping?

For those just joining us, molecular manufacturing plans to build nanoscale components by joining molecules together under programmable control. The goal is to build a machine that can join molecules--which can then build two side-by-side, which can work in parallel build four, and so on. Add nano-built computers and a little bit of micron-scale structure, and you've got a nanofactory: a tabletop machine that can make any of a wide range of products.

The following are some reasons why a nanofactory will be far more powerful and transformative than a present-day rapid prototyping system:

1) Maintenance of precision. By adding just a bit of energy to remove entropy, atom-built objects can be essentially perfect to N generations. Because atoms of an isotope are all exactly the same, the products can be exactly the same.

2) Low friction. Perfect atom-built objects can take advantage of superlubricity and zero wear. Micro-scale objects have serious problems with wear due to scaling laws.

3) High performance. For many machines, including electrostatic motors, performance increases with decreasing size. Aggregations of nanoscale machinery should be more powerful than microscale machinery by several orders of magnitude.

4) More applications. Especially medical applications.

5) More flexibility of construction. By controlling how the atoms and molecules are joined, you can make different materials as well as different shapes. Also, with improved functional density, it's easier to design products.

6) Chemistry in products. It'd be hard to build stuff like fuel cell membranes with micro-fabricators. It should be easier with molecular manufacturing.

There are probably other advantages as well.

RepRap is a great project. And it's worth noting that an inkjet printer can print its weight in ink in about a day. Micro-scale exponential manufacturing is neither impossible nor worthless. But nano-scale exponential manufacturing will be a whole lot better.

So, will there be a continuum between micro and nano fabrication? Only in the sense that there was a continuum between ENIAC and a modern Web-enabled PC with a Google homepage.

In some ways, there was a continuum. But there were also a lot of breakthroughs and sudden leaps in capability. The average person never saw a $20,000 PC, and never used BITNET. ENIAC simply couldn't run a GUI (though the first video game dates back to the 50's, if I remember correctly).

In some ways, there may be a continuum between micro fabs and nano fabs. Micro fabs already make products like shoes; RepRap includes rapid-prototyped wires; eventually micro-fab products may even include fab-built electronics and actuators and sensors.

So in the sense that they both make products, there's a continuum, just as ENIAC and Pentium both could crunch numbers. But for the reasons listed above, molecular manufacturing will be able to do a whole lot of stuff that micro-fabs simply can't do. RepRap would be able to build a lot of the things you find in the typical 99-cent store. But it's hard to imagine building an airplane, or a rifle, or an artificial kidney, or a supercomputer, with RepRap. All these things, and many more, should be buildable in unlimited quantity with a nanofactory. That will be truly revolutionary.

Chris Phoenix

Tags: nanotechnology nanotech nano science technology ethics weblog blog

Comments

[Nato Welch]

Thanks for the reply!

I wasn't meaning to imply that working at the molecular scale had little to no value; obviously there's a lot. I was just trying to describe the social shock factor that such machines would bring with them. More than any other factor, I would still have to say that the recursive nature of these devices is the most profound. The exponential growth curve one can plot with the first fabs is the most novel, and it's driven by self-replication ability. Once people get over the shock of exponentially-propagating machines (not to be confused with grey goo), people will begin to "get it", and start thinking more accurately about what they can expect next from these fabs. That's when I think groups like foresight and CRN will really start finding themselves listened to by policymakers.

Still, you do bring up a good point in the analogy to computers. Computing machines made a great many changes to the averge person's life before the computers themselves even broached their consciousness. In the same way , we might expect only geeks like me to really care about the first generations of the RepRap.

One important difference is that, unlike Computers, what would keep RepRap out of people's homes wouldn't be expense, but interest. Fabs are cheap right off the blocks, whereas PC's needed to wait for Moore's Law to bring the prices down before the real impact could be felt. With recursive fabs, people will be able to have one as soon as they discover it does something they want. Obviously, this diffusion into common life is going to be a LOT faster than for computers.

I have no doubt that molecular scale fabs will have vastly superior capabilities over microscale fabs. But will fabs really produce any phenomena so startling revolutionary as their own exponential growth?

[Tom Craver]

The problem I see with most current fabbers is that they rely on exotic materials - special plastics and metal powders and such - as feedstock.

Much more useful would be a low cost fabber that converts trash to something useful - e.g. plastic bottles and cardboard into sheets suitable for roofing and walls.

[Janessa Ravenwood]

Tom: Oh, yeah. That one would make friends fast. Not to mention, recycling = good in and of itself.

[Chris Phoenix, CRN]

I've answered your comment in a new post here. Thanks for the interesting discussion.

Chris

[Monty]

Hey, I had a look at your nanofactory idea and was thinking... wouldn't it be better if it was round instead of square? Pressure vessels are usually cylinders or spheres to avoid stress concentrations.