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Yale scientists model artificial energy cells

Yale Medicine Magazine, 2009 - Winter


Chemical engineers design an artificial electrocyte that could be a power source for medical implants.

Researchers at Yale University have created a blueprint for artificial cells that are more powerful and efficient than the natural cells they mimic and could one day power tiny medical implants. Their findings were published online in Nature Nanotechnology on September 21.

The scientists began by exploring whether an artificial version of the electrocyte—the energy-generating cells in electric eels—could be designed as a potential power source. “The electric eel is very efficient at generating electricity,” said Jian Xu, Ph.D., a postdoctoral associate in the Department of Chemical Engineering. “It can generate more electricity than a lot of electrical devices.”

Xu came up with the first blueprint that shows how the electrocyte’s different ion channels work together to produce the fish’s electricity while he was a graduate student under David A. LaVan, Ph.D., a former assistant professor of mechanical engineering now at the National Institute of Standards and Technology.

But the scientists didn’t stop there. “We’re still trying to understand how the mechanisms in these cells work,” said LaVan. “But we asked ourselves: ‘Do we know enough to sit down and start thinking about how to build these things?’ Nobody had really done that before.”

Using the new blueprint—based on a mathematical model—as a guide, LaVan and Xu set about designing an artificial cell that could replicate the electrocyte’s energy production. “We wanted to see if nature had already optimized the power output and energy conversion efficiency of this cell,” said Xu. “And we found that an artificial cell could actually outperform a natural cell, which was a very surprising result.”

The artificial cell LaVan and Xu modeled is capable of producing 28 percent more electricity than the eel’s own electrocyte, with 31 percent more efficiency in converting the cell’s chemical energy—derived from the eel’s food—into electricity.

While eels use thousands of electrocytes to produce charges of up to 600 volts, LaVan and Xu have shown that it would be possible to create a smaller “bio-battery” using several dozen artificial cells. The tiny bio-batteries would need to be only about a quarter-inch thick to produce the small voltages used to power such tiny electrical devices as retinal implants or other prostheses.

Although the engineers came up with a design, it will still be some time before the artificial cells can be built—they will still need a power source. LaVan speculates that the cells could be powered in a way similar to their natural counterparts. Bacteria, he suggested, could be employed to recycle ATP—the molecule that transfers energy within cells—using glucose, a common source of chemical energy derived from food.

With an energy source in place, the artificial cells could one day power a medical implant and would provide a big advantage over battery-operated devices. “If it breaks, there are no toxins released into your system,” said Xu. “It would be just like any other cell in your body.”