It may sound like something out of a Popeye cartoon, but MIT researchers are building a promising solar cell from spinach. In their Cambridge lab, bioengineer Shuguang Zhang and electrical engineer Marc Baldo shine a laser beam on a chip the size of a postage stamp. Out of a wire electrode hooked to the chip comes electricity – a trickle now, but one day, perhaps, enough to power a cell phone or laptop. Instead of the silicon found in most solar cells, however, this chip uses proteins from plants that have evolved over millions of years to turn sunlight into usable energy.
The advance “is of tremendous importance,” says Peter Peumans, an expert on organic electronics at Stanford University, because solar cells that draw on plants’ natural photosynthetic ability could eventually be lighter, cheaper, and easier to repair than their conventional cousins.
Biological cells removed from plants and connected to electronic hardware typically die within hours. But Zhang and Baldo, collaborating with the University of Tennessee and the U.S. Naval Research Laboratory, took wholesale spinach and harvested just the proteins that absorb photons and generate free electrons during the process of photosynthesis. The researchers bathed the proteins with detergent-like molecules that would keep them working properly on a dry surface for weeks. They then placed the proteins on a gold-coated glass substrate and deposited a semiconductor layer on top to collect electricity.
So far, the chip’s energy efficiency is far lower than that of existing solar cells. But “extensions of these methods could produce very important future energy conversion technologies,” says MIT chemist Timothy Swager. To ratchet up the chip’s efficiency enough that it could power a mobile device, says Zhang, the researchers plan to increase the area of its light-absorbing surface by building layers of proteins on wavy substrates. Zhang predicts the technology could be used commercially in five years.
How AI is reinventing what computers are
Three key ways artificial intelligence is changing what it means to compute.
These weird virtual creatures evolve their bodies to solve problems
They show how intelligence and body plans are closely linked—and could unlock AI for robots.
Our brains exist in a state of “controlled hallucination”
Three new books lay bare the weirdness of how our brains process the world around us.
We reviewed three at-home covid tests. The results were mixed.
Over-the-counter coronavirus tests are finally available in the US. Some are more accurate and easier to use than others.
Get the latest updates from
MIT Technology Review
Discover special offers, top stories, upcoming events, and more.