As a child, Angela Belcher harbored a burning desire to be an inventor.
Her lab was the family garage in Houston. “I’d go in there and say to myself, ‘I’m not leaving until I invent something,” notes Belcher. “And it was really hot, over 100 degrees. But there I would be….”
In the end, she came up short. “I never really invented anything,” she says. But that was then.
Belcher, now an MIT associate professor of materials science, has emerged as a path-finding inventor and innovator. Her best-known invention is a new technique for creating objects from minuscule wires, to energy-efficient solar-panel materials, to smart textiles that can signal the presence of dangerous infectious agents. What makes the approach amazing is that the fabricators include some of the smallest organisms anywhere — viruses.
Viruses are truly tiny: a billion of the ones Belcher uses “could fit into a single drop,” she notes. But they’re also great for her purposes.
If you want to build materials atom by atom or molecule by molecule — a process leading to what are called nanostructures — viruses are the right size. The ones Belcher uses are safe and environmentally benign. It’s easy to reproduce them. And, they can be genetically screened for their ability to link up with and cling tenaciously to one of many types of materials: semiconductors like the silicon used in computer chips, carbon, iron, and the metal oxides that make up the anodes and cathodes in batteries, for example.
Why would you care? Say you wanted to fabricate, using a nanostructure approach, a new kind of electronic chip. What you need for starters is a way to manipulate minuscule quantities of a semiconductor like silicon. Well, you can do that with the right kind of viruses: that is, “viruses with particles of silicon attached to their heads,” explains Belcher.
With help from such viruses, Belcher and her co-workers are today rewriting the manuals on building stuff from the atomic level up.
Starting with Abalone
Belcher’s work has already brought her many honors, including a MacArthur Foundation Prize Fellowship, or “genius grant.” But how did a frustrated child inventor wind up as the creator of an extraordinary new method for making things?
A seventh-generation Texan, Belcher assumed she’d go to college there after finishing her elementary and secondary schooling. Instead, though, she applied to a school-within-a-school called the College of Creative Studies at the University of California Santa Barbara.
It was a smart decision. In choosing courses, Belcher notes, “you were never told no. I took anything I was interested in, including grad courses in chemistry and molecular biology.”
Picking UCSB also put her in touch with one of the world’s experts on abalone. These under-water snails are a culinary delicacy. What intrigued Belcher, though, was the abalone’s shell.
“They’re 98 percent calcium carbonate — in other words, chalk,” she says. “But they’re 3000 times stronger than chalk.”
For Belcher, the key point was that nature, in the form of the abalone “animal” — the meaty entity beneath the shell — was creating this amazing material out of a common mineral.
After exploring the phenomenon as a UCSB grad student, she wondered if she could mimic nature. She had various schemes for doing so before her “Eureka moment” about viruses. Still, the decision to use viruses took a long time to pay off, partly because it involves a tortuous screening process.
The Best Binders
Why is the process so laborious? Because you have to test many millions of the organisms for their ability to bind tiny bits of a target mineral; generate huge quantities of those specific viruses; choose the ones in the next batch with the best binding traits — and so on.
By 1999, though, Belcher and her co-workers reported they could indeed create huge armies of viruses that would bind specific materials. They also said the organisms could be used to create new types of structures.
One key reason the system works is that viruses are easy to manipulate. Thus, to make an ultra-thin wire, says Belcher, you can take viruses bound to particles of a material of choice, “shoot them through a very small hole, and form fibers on the scale of a meter or more.” Those fibers, in turn, could be used for various applications, among them making pathogen-sensitive clothes.
Today Belcher, a member of the new MIT Energy Research Council, is involved in several projects with energy applications. For example:
- light-emitting materials that are bright, energy efficient, and able to be structured in almost any way imaginable;
- solar panels made from gallium nitride that would achieve unprecedented levels of efficiency; and
- rechargeable batteries that would be self-assembled, transparent, highly efficient, a millionth of a meter thick, and able to be, in effect, “poured over” the item they’d be powering — for example, night-vision goggles. (Belcher’s collaborators on this project include two other faculty: Yet-Ming Chiang, a materials science professor, and Paula Hammond, a chemical engineering associate professor).
Not all Belcher’s work involves viruses. Some newer fabrication crews are made up of yeast, the one-celled organism critical to consumable items from bread to beer.
Unlike viruses, says Belcher, the much larger yeast would make components, not complete devices. “Think of them as little factories that turn out nanomaterials,” she says. “We’re working on yeast that can grow electronic, optical, and medical materials.”
And longer term? The group’s goal, says Belcher, is to have some kind of biologically based system “that can make any kind of material you like.”