Thursday, September 28, 2006

Powerful Batteries That Assemble Themselves

Continued from page 1

By Kevin Bullis

TR: People are looking at different organisms to try to create bioengineered materials, like sponges, diatoms, or abalone shells. Why did you choose viruses?

AB: Well, for a couple of reasons. What a lot of people think is interesting about biological materials is looking at the final structure. I did my PhD [work] on that and I think it's a very interesting question. But that's only going to get you so far. It will get you to understand how to make a diatom, or something very similar to a diatom.

To me, [what is] more interesting is that when an abalone makes offspring, it makes millions and millions of offspring that have the genetic information to build a beautiful shell. Wouldn't it be great to be able to pass on genetically the ability to make a material, in this case battery material, solar cells, or all kinds of other things we're working on? If you're going to genetically manipulate a sponge or an abalone to change their offspring, it's going to take a really long time, and it's going to be very complex. Viruses are very easy to work with. They're only DNA and protein. You don't have to worry about messing up all kinds of other metabolic processes, and you can make millions of copies in a very short amount of time.

TR: But these other organisms already work with inorganic material. With viruses you don't have that. Would you explain how you're able to get them to assemble these materials?

AB: It's actually borrowed from the idea of how those other organisms make materials, being able to grab onto ions out of solution and position them to make bonds and materials.

We've done a lot of experiments, so we know the kinds of amino acids that are good at binding different materials. For the cobalt oxide material, all we had to do was bind cobalt, and to do that, we used high concentrations of carboxylic acid proteins. The gold part we did through selection [creating millions of variations, and isolating the DNA of virus proteins that bind well to gold]. Then [we] put the DNA sequence that is good at capturing cobalt into the genome of the virus, with the sequence [for gold] in a different part.

TR: You've said before that you hope to be able to simply mix together precursors and viruses and then pull a complete device out of a beaker. How is that going?

AB: We're definitely heading in that direction. We're working very hard on being able to make the other electrode material. We expect to be there in another couple of months. In that case we'll have the two electrodes and the electrolyte. We could probably think of doing something similar for the collector. So I don't think it's a complete fantasy. I think we'll be able to do that in a short time, like within a year.

TR: Where will we see these batteries first?

AB: We're working on spinning them into fibers for textile-integrated materials that would be inexpensive. We have ideas of how to make transparent stick-on batteries that look like Band-Aids. People are also interested in applications like smart cards, and I think that that's definitely a possibility. Things that are really lightweight, cheap, and both rechargeable and disposable.

TR: Do you see applications in transportation?

AB: I'm having companies come talk to me about that. I don't see how to scale it yet, because mostly we focus on making things very, very small. But I definitely don't see it out of the realm of possibility at all, because for hybrid cars and so on, you're going to want to have light-weight batteries.