Researchers Build the "World's First Wooden Transistor," Aim at Control of "Electronic Plants"

Researchers at Linköping University and Sweden's Royal Institute of Technology have developed what they claim to be the world's first transistor to be made out of wood — a move they claim paves the way for eco-friendly wood-based electronics and even control over "electronic plants."

"We've come up with an unprecedented principle," claims Isak Engquist, senior associate professor and corresponding author on the paper detailing the breakthrough. "Yes, the wood transistor is slow and bulky, but it does work, and has huge development potential. We didn't create the wood transistor with any specific application in mind. We did it because we could. This is basic research, showing that it's possible, and we hope it will inspire further research that can lead to applications in the future."

The transistor, patented in 1925 by physicist Julius Edgar Lilienfeld but never practically produced until the work of John Bardeen, Walter Brattain, and William Shockley at AT&T's Bell Labs in 1947 and 1948. Designed to replace the thermionic triode vacuum tube, the transistor was smaller, lighter, and more reliable — and in the decades since has been miniaturized to the point where a single integrated circuit might contain billions upon billions of them in a tiny footprint.

What the Swedish researchers have created is, in its function, little different to the Bell Labs prototypes — except that it's made from balsa wood, from which the lignin is removed and the remaining hollow channels filled with a conductive plastic polymer. While, admittedly, the resulting device is at least as much plastic as it is wood, it conducts electricity — and can function continuously, unlike previous attempts at wooden electronics.

While the team's work is an undoubted breakthrough, the prototype does come with a few drawbacks. The first is size: while considerably smaller than the point-contact transistor prototyped by Shockley and colleagues all those years ago, it's absolutely gigantic compared to modern silicon transistors. It's also much slower: activating the device takes around five seconds, the researchers admit, while deactivating it takes another second.

Despite this, the researchers believe the concept has practical applications — including the regulation of "electronic plants," and use in higher-current applications for which rival organic transistors are ill-suited.

The team's work, which was supported by the Knut and Alice Wallenberg Foundation via the Wallenberg Wood Science Center, has been published in the journal PNAS under open-access terms.

Main article image courtesy of Thor Balkhed.