Algae used for Computer Chips

Biologists and engineers work with a unicellular algae, known as the diatom, for computer chip nanofabrication.
April, 2008
Engineer: a person who uses scientific knowledge to solve practical problems.
Biologist: a specialist in the science of life and of living organisms, including their structure, function, growth, origin, evolution and distribution.
Professor Franco Cerrina explains the electrical aspects of diatom research.
These two fields of study form a natural pairing for Michael Sussman, professor of biochemistry at UW-Madison, and Franco Cerrina, professor of electrical engineering at UW-Madison. “You can’t get much more interdisciplinary than what we’ve been doing,” Sussman says.
“We do something together that we couldn’t do alone,” Sussman says. As engineers, the importance of teamwork is regularly stressed; however, Sussman was referencing something slightly different. He has been working with Cerrina to discover industrial applications for a unique biological organism—the diatom.
Diatoms are unicellular algae encased in cell walls made of silicate, a form of silicon. In engineering, silicon is used in the nanofabrication of computer chips. Sussman understands the chemistry and mechanisms behind researching the diatom’s structure, while Cerinna is an expert in the nanofabrication process. By combining both of their concentrated scientific backgrounds, they were able to recognize the potential use of diatoms in computer chip manufacturing.
“The chips are getting smaller and smaller and higher and higher density,” Cerrina says. However, engineering technology has already reached its smallest possible chip. The speed cannot be further increased unless a new method of production is designed.
“You can do it yourself and that is what we are doing today. You develop the techniques yourself and make things smaller and smaller… Or you can take something that already knows how to make small things and use it as a tool,” Cerrina says.
“Synthetic biology. Let’s assume that we know system biology. Can we use that to build new things?” Cerrina says of how the idea was initiated. These diatoms are able to “make little machines—little structures in dimensions that engineers have trouble with,” Sussman says. “We are hoping that we can discover how they do that.”
“No one has been able to genetically modify [the diatoms], to manipulate them and use them,” Sussman says. When a team at the University of Washington was able to sequence the diatoms, Sussman knew he was part of an amazing research project. “This group of organisms is so far out there,” Sussman says. “In this case, prior information is useless.” The diatom is the first silicate-requiring organism that has ever been studied.
How exactly did this discovery take place? Cerrina, Sussman and their teams built a microarray synthesizer to make DNA chips. Then they decided to starve the organisms of silicate to see which genes get turned on and which get turned off. It is “an easy way to figure out which genes are involved in the [nanofabrication] process,” Sussman says.
The organisms were similarly starved of nitrogen, carbon and other important components that have been previously studied on known systems. “Out of the 10,000 genes, 2,000 genes were affected by one of those conditions,” Sussman says. “Out of the 2,000 genes, we identified 75 genes that were specifically impacted by silicate starvation... 67 of them have no sequence seen before.” Since this is the first researched organism that requires silicate, they think an entire world of silicate chemistry is yet to be discovered.
A second investigation performed at UW-Madison was to find out where in the cell the genes specific to the silicate process exist. It is hypothesized that they are in the cell wall since this is the silicate’s location. In order to test the theory, the diatom protein was modified by fusing half with a glowing jellyfish protein.
“It glows in the cell wall,” Sussman says. “We are going in the right direction.” Next on the agenda is to mutate the genes, create imperfect cell walls and overexpress the organisms to see how they react, a process known as “reverse genetics.”
What about these possible computer chips that may be formed by “reprogramming” the diatoms? In what kind of computer will they be used? “It is not going to be a computer in the way that we know a computer,” Cerrina says. “[The diatoms] will be nanofabricators… The plan is to teach these diatoms to fabricate the shape that we want, not the shape that they want.” The process is analogous to taking a machine that is designed to make sunglasses and reprogramming it to create reading glasses.
Located in the NanoTech Lab, the microarray
synthesizer is an essential instrumentation
device for researching the specific genes of diatoms.
“We are trying to make biological systems to mimic engineering systems,” Cerrina says. “We are trying to find the set of instructions to make the diatom work.”
Finally, the scientists will want to modify the diatom’s set of instructions for purposes of computer chip production.
“It’s a new time that requires collaboration.” Natural science needs people who are comfortable in thinking outside of their own area. “Engineers are very good at this,” Sussman says.

http://www.engr.wisc.edu/wiscengr/cgi-bin/archivearticle.php?article=apr08breakthrough
Wisconsin Engineering Magazine – 2008
Written by Sally Green