Invisible Engineering

Angela Belcher, a materials chemist at the Massachusetts Institute of Technology, is using nanotechnology to grow batteries. Out of viruses. Batteries that could last weeks or months and be thinner than a credit card. How did she get such an idea? Abalone shells.

“I’m really interested in how biology makes materials,” Belcher says. “I’ve always been fascinated, for instance, with shells.” Abalone seashells are made up mostly of calcium carbonate but because of how abalones mix that soft material with proteins at nanoscale sizes, the shells form a nearly unbreakable armor. “A lot of objects controlled at the nanoscale have unusual properties based on how they are made biologically,” she says.

Working in her lab with materials scientists and bioengineers, Belcher started with a naturally occurring virus called the M13 bacteriophage and inserted genes that caused the virus to become a template for tiny, self-assembling wires. Some wires, made of cobalt oxide and gold, become the negative poles of the battery. Others, made of iron phosphate covered in carbon nanotubes, form the positive poles. The ultrathin wires, several nanometers in diameter, can be combined to form high-power electrodes for lithium-ion batteries like those used in many modern electronics. But Belcher’s batteries can be engineered into any shape imaginable.

Belcher’s wizardry has attracted attention from the highest levels of government. President Obama stopped by Belcher’s lab for a demonstration. She gave him a miniature copy of the periodic table of elements. (“In case you’re ever in a bind and need to calculate a molecular weight, here’s a periodic table for your wallet,” she told him.)

Belcher’s batteries are at least a few years away from commercialization. They may show up first in a new generation of computerized credit cards. Or long-lasting lightweight batteries for gadgets like laptops or cellphones—or a lab on a chip.