Popeye uses spinach to power his muscles. Now, scientists are looking to spinach as a power source for making electricity.
A solar cell converts sunlight into electricity. Most of these, today, are made of a material called silicon. The new device instead uses proteins from spinach and from a bacterium called Rhodobacter sphaeroides.
To make the solar cell, a team of biologists and chemists at the Massachusetts Institute of Technology in Cambridge extracted certain light-sensitive proteins from the spinach and the bacteria. They placed about 2 billion of these proteins on a piece of glass. They made the proteins stick by embedding them in a special framework that looks and acts like a cell membrane.
The researchers then samdwiched the layer of proteins between layers of other materials called semiconductors. Those other materials carry electricity. Then the scientists shone certain types of light on the device. The proteins absorbed the light and sent electrons through the semiconductor to an electrode. This activity caused an electric current to flow.
In this solar cell, light-sensitive proteins obtained from spinach and bacteria (yellow spheres) absorb light and pump electrons (e–) into a silver electrode.
|Courtesy of Marc Baldo, Massachusetts Institute of Technology|
At this early stage in the research, the spinach cell isn’t efficient enough to be useful. To improve their solar cell, the researchers want to jam more proteins into a single device. They also want such solar cells to stay active for a long time. One hope is that protein-based solar cells might repair themselves, just like living plants replace their own proteins over time.
If it all works out, there may be a new way to harvest the sun’s energy. Instead of just eating your spinach, you might rely on the leafy green to power your TV set.—E. Sohn