Ari Requicha’s MOLECULAR ROBOTS

by Max More, Ph.D.

Prof. Ari Requicha taught the first course based on Eric Drexler’s seminal work on molecular nanotechnology, Nanosystems. He is Professor of Computer Science and Electrical Engineering at the University of Southern California and founder of the Laboratory for Molecular Robotics at USC.

A: The lab is very new. We have 4 principal investigators. My background is in robotics and automation, in computer-aided design and geometric models. So I am interested in spatial reasoning. What I’m really known for is solid modeling, which has to do with representing solid objects in computers.

The other principal investigators: one is Peter Will, the division leader at the Information Sciences Institute. His main work has also been in the robotics and observation area. Then we have material scientists, computer science and physics people, and we have a chemist who also has an appointment in materials, and he is a surface science person.

M: What are the short term and long term goals?

A: The very long term goal is to build nanomachines and to do things such as determine the structure of materials by probing them with atomic force microscopes and instruments like that which for us is an exercise in tactile sensing. We are saying that instruments like scanning tunnelling microscopes (STMs) and atomic force microscopes (AFMs) seem to be the most promising way we have now to manipulate very small things, nanometer-scale things, and they turn out to look a lot like robots in what they are doing.

We are hoping to work with room temperatures and compensate for a variety of problems by being clever with software and using the right sort of robotic strategies. In the short term what we want to do is take silicon substrates, basically semiconductive substrates, probably silicon and build mezzas. What we want to do is grab some interesting molecules with an STM and put them on top of these mezzas and create an array. That will show that with a little more work one could probably build interesting atomic devices with this approach. It has to be something that can not be done by stan-

dard semiconductor processing. So that’s our first objective.

M: What is the difference between the SPM and STM?

A: An SPM is sort of a generic name. Scanning Probe Microscope is a generic name for all these machines. It include atomic force microscopes. An STM is a tunnelling microscope, AFM is the force microscope, sometimes it’s called an SFS, a scanning force microscope, then there are others. Things that work with temperature and magnetic fields. These all fall under this thing: scanning probe microscopes.

So far SPMs have been mostly designed as imaging instruments. Now what we want to do is use them as robots. If one were to design an SPM with the thought that this is going to be primarily a manipulator you might design it differently. There may be some breakthroughs. One of the big problems we have is that it is hard to know where the probe is in XY

computational notion. Computation in computer science is mostly about how to use a small number of primitives to do complex things. And here you have these hardware primitives which are atomic things and you want to combine them in interesting ways.

It’s like having a language where you can make interesting sentences using a bunch of characters and sounds. If you try to do that then you are doing assembly, and assembly is something that the robot people have been studying for many years. So when you talk about molecular robotics you are talking about assembling things out of molecules and atoms and that’s really very much like what Drexler and others want to do.

It’s very exciting you know. If any of this works, it’s going to be great. What it’s going to do is let you do with the structure of matter the kinds of things we do with the structure of information. We’ve got this bit and we’ve figured out how to put bits together and to build from there. We

What it’s going to do is let you do with the structure of matter the kinds of things we do with the structure of information.

with enough accuracy. It’s not like a standard robot where you have encoders in the arms and you know exactly where your hand is fairly accurately. So if you can redesign things to be manipulators they might come up differently and better. Technology is evolving pretty rapidly. A lot of people are trying new designs right and left, so something might happen. There are some basic problems one being that probes are very big still, they are 29 nanometers diameter which is a very big thing to move an atom that’s a tenth of a nanometer.

M: Having taught the course on Drexler’s Nanosystems you are familiar with the wide coverage of the book. How does molecular robotics fit into what Drexler describes as molecular nanotechnology?

A: Molecular robotics would cover a lot of it because in essence what Drexler and everybody else is trying to do is build things from the bottom up. It’s a very

can build these programs with millions of lines of code that are probably the most complicated things that humans have ever built. We’ve got that fairly well under control. Now, if we start playing with hardware primitives that are in the materials and we manage to have anything that resembles that ability to combine them in new ways, you could do… well, I’m sure there are going to be applications that we cannot even think about now.

M: Do you want to be around to see the consequences of this in 50 or a 100 years?

A: Sure! I plan to be around hundred years from now.

M: Do you have a program of action to make that happen?

A: Drink as much as possible, that sort of thing. [Laughs.] Unfortunately I don’t think I’ll be around to see it, but I might be around to see the beginning of it.

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