A team in Europe are working with wood, but not in the usual ways. They are not carpenters（木匠）. Instead, they are scientists exploring how wood can lead to a greener electronic device, a transistor（晶体管）made from balsa wood, whose production releases less climate-warming gas into the air.
Transistors play an important role in computers and other devices. They act like tiny switches to control the flow of electricity. Engineers use them to process and store data. Today's laptops may host billions of them. So they must be tiny—only a little wider than a strand of DNA.
The new transistor being built by physicist Isak Engquist and his team at Sweden's Linköping University isn't as small as those. Big enough to see and hold, it can stand only an electric pressure that pushes electrons along. And it controls a current using charged particles（粒子）called ions.
This new technology shows a "proof of concept" that the idea can work, even if the new device is not yet ready to put into today's electronics. "While it seems large by today's standards, such a transistor still might prove useful for electronics that require low electric pressures," says Engquist.
"The new transistor suggests that future electronic devices might be made in living plants," Daniel Simon, a physicist in the team, says. "Imagine peeling away some bar k from a living tree," he says, "and stamping electronic circuits into the living wood."
In fact, Engquist says, "There are so many ways we can use wood and the components of wood that we would never have thought of." For instance, he can now imagine a wood-based sensor that could monitor crop health, measure pollution or survey a forest for fire risk.
