Researchers from Linköping University and Sweden’s Royal Institute of Technology have created what they call “the world’s first transistor made out of wood”, a move that could lead to the development of eco-friendly wood-based electronics and even the control of electronic plants. They used balsa wood treated with a conductive plastic polymer to create the wooden transistor — while the resulting device is at least as much plastic as it is wood, it is an important breakthrough because it is the first time that a functional electronic device has been built using wood as its base material.

The wooden transistor was not created with any specific application in mind, but rather to show that it was possible. It is admittedly large and slow compared to modern silicon transistors, taking about 5 seconds to activate and another second to deactivate. Despite these drawbacks, the researchers believe that the concept has practical applications, including the regulation of “electronic plants” and use in higher-current applications for which organic transistors are not well-suited.

The transistor is a fundamental building block of modern electronics, allowing the control of the flow of electrons in a circuit. The first one was patented in 1925 by physicist Julius Edgar Lilienfeld, but it was not until 1947 and 1948 that the transistor was practically produced by John Bardeen, Walter Brattain, and William Shockley at AT&T’s Bell Labs. Transistors replaced the thermionic triode vacuum tube, making electronics smaller, lighter, and more reliable. Since then, the transistor has been miniaturized to the point where a single integrated circuit can contain billions of them.

The wooden transistor functions similarly to Bell Labs’ prototypes, but it is made from balsa wood with its lignin removed and the remaining hollow channels filled with conductive plastic polymer. This combination allows it to conduct electricity and function continuously, unlike previous attempts at wooden electronics. The researchers’ work is supported by the Knut and Alice Wallenberg Foundation via the Wallenberg Wood Science Center and has been published in the journal PNAS under open-access terms.

While the wooden transistor has limitations, it is an important step in the development of eco-friendly electronics; with further research and development, the concept could lead to the creation of wood-based electronic devices that are more environmentally sustainable than their plastic and silicon counterparts — additionally, the wooden transistor could be used to regulate the growth of plants with electronic sensors, which would have important applications in agriculture and environmental monitoring.

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