Airplane parts, golf clubs, hip implants—all contain titanium, one of the planet’s strongest lightweight metals. Now scientists are building a product that’s even stronger and lighter. Tomorrow’s high-performance tools may be made of metallic wood.
Metallic wood doesn’t come from a tree. This “wood” is made in a lab. James Pikul of Penn Engineering says that under a microscope, metallic wood looks like a honeycomb or scaffold. It’s really a sheet of nickel with tiny pores—like those found in wood grain. The pores make the material as strong as titanium but light enough to float.
Pikul and colleagues from several universities around the globe owe their metallic wood success to observations of God’s creation.
“The reason we call it metallic wood is . . . its cellular nature,” Pikul says. He refers to wood grain as having “parts that are thick and dense and made to hold the structure, and parts that are porous and made to support biological functions, like transport to and from cells.” Pikul sees metallic wood as similar in structure—thick, dense metal rods with air gaps in between.
Researchers also plan someday to riff on God’s cell transport design: by infusing those gaps with diodes and cathodes—battery-making supplies. They’re looking ahead to developing a plane part or prosthetic arm that’s self-charging, for example.
To make metallic wood, Pikul uses plastic spheres much smaller than the diameter of a human hair. His method involves suspending them in water, covering them with a thin layer of nickel, and then dissolving the spheres. What’s left is a network of metal crosspieces—and lots of air.
The air pockets mean that about 70% of metallic wood is empty space, so its density is low compared to its strength.
Reproducing this process in volume comes next. So far, engineers have been able to produce only postage-stamp-sized amounts of metallic wood. Someday, they hope to use larger pieces to wrap sturdy, ultra-light electronic devices or strong, fuel-efficient cars.
The materials—plastic, water, and nickel—aren’t rare or costly. But for now, working on an atomic scale is time-consuming and therefore expensive. Once researchers figure out the best way to work small, they believe producing large quantities of metallic wood will become faster and more affordable.
“We’ve known that going smaller gets you stronger for some time,” says Pikul. When comparing strength to weight, it appears small is the new big.
