The world’s first electrical transistor made of wood. Photo: Thor Balkhed.
The world’s first electrical transistor made of wood. Photo: Thor Balkhed.

Researchers at Linköping University and the KTH Royal Institute of Technology, both in Sweden, have developed the world’s first transistor made of wood. Their study, reported in a paper in the Proceedings of the National Academy of Sciences, paves the way for further development of wood-based electronics.

Transistors, invented almost 100 years ago, are a crucial component in modern electronic devices, and can be manufactured at the nanoscale. A transistor regulates the current that passes through it and can also function as a power switch. Researchers at Linköping University, together with colleagues from the KTH Royal Institute of Technology, have now developed the world’s first electrical transistor made of wood.

“We’ve come up with an unprecedented principle,” says Isak Engquist, senior associate professor at the Laboratory for Organic Electronics at Linköping University. “Yes, the wood transistor is slow and bulky, but it does work, and has huge development potential.”

In previous trials, transistors made of wood have been able to regulate ion transport only. And when the ions run out, the transistor stops functioning. The transistor developed by the Linköping researchers, however, can function continuously and regulate electricity flow without deteriorating.

The researchers used balsa wood to create their transistor, as the technology requires a grainless wood that is evenly structured throughout. They removed the lignin from this balsa wood, leaving long cellulose fibers with channels where the lignin had been.

They then filled these channels with a conductive polymer called PEDOT:PSS to produce an electrically conductive wood material. The researchers used this material to build the wood transistor, and then showed that it can regulate electric current and provide continuous function at a selected output level. It could also switch the power on and off, albeit with a certain delay – switching the power off took about a second, while switching it on took about five seconds.

Possible applications could include regulating electronic plants, which is another strong research area at Linköping University. One advantage of the transistor channel being so large is that it could potentially tolerate a higher current than regular organic transistors, which could be important for certain future applications. Although such applications weren’t upmost in the researchers’ minds.

“We didn’t create the wood transistor with any specific application in mind,” says Engquist. “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.”

This story is adapted from material from Linköping University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.