How Small is Small?

Maryland's John Fourkas is a master of the itty bitty. The young chemistry professor works in the world of three-dimensional microscopic machines so tiny you can't see them. They do things like deploy airbags and make cell phones work. They may one day be used to deliver medication to a very specific area of the body or do magnetic resonance imaging from inside a single blood vessel.

So far, micro technology has used silicon as the major construction material, which limits potential applications. Fourkas is changing that. He's finding ways to construct micro machines with a variety of materials and in mass quantities, discoveries that could pave the way for entirely new types of micro machines.

(Interview with John Fourkas below)

How do you make these micro machines?
Fourkas: It's much like when the dentist makes a composite filling for your teeth. He puts the liquid filling in, then hits it with ultraviolet light, which hardens it. We do the same thing with a special instrument. We take some liquid and hit it with a laser beam, which hardens the liquid only in that spot. We focus the laser beam through a microscope.

What are the challenges in making these micro machines?
Fourkas: One of the problems is that the techniques are quite limited. It's not just a matter of converting techniques we already have. Also, existing commercial techniques use silicon, which limits their uses. Our laser technique employs polymers, but another challenge is that is that structures must be made one at a time, which is not conducive to production on a commercial scale.

How are you improving the techniques?
Fourkas: One thing we're doing is developing ways to work with chemicals that are commercially available and that can be formed into shapes with low laser power, and to incorporate other materials into the process. Our aim is to do everything on a desktop, to program a computer to do the work.

What is your latest success?
Fourkas: Our lab has developed a method that lets us use our laser technique to make micro machines from materials besides plastic, including metals. (First image in gallery - "UMD"). We have also devised a way to reproduce our structures rapidly, an important step in making laser fabrication commercially viable.

What was an "Aha!" moment for you?
Fourkas: Reproducing structures with closed loops. We were told that it was impossible to reproduce a three-dimensional structure with loops because the mold jams in the holes. We developed a way around this problem so that we can reproduce bridges and other structures with openings.

What's on the horizon?
Fourkas: We're working on ways to produce structures in mass quantities. We can mold a huge variety of structures. I think that will include moving parts.

Have you always thought you would be in chemistry?
Fourkas: My father was the science writer for the Sacramento Bee for many years, so I grew up around science, but I thought I would be an astronomer. A fantastic high school chemistry teacher changed all that, although I didn't realize it until I had been in college for a year.

Why do you teach?
Fourkas: It's so much fun. You get great students. I learn as much from them as they do from me.