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Every electrical device causes electromagnetic interference as all charge carriers that are accelerated or decelerated emit electromagnetic fields that spread through space. At the same time, every device is also a receiver of interference. Here, the interference can reduce the performance of the device or even bring it to a standstill. In the case of data transfer, these effects can range from an increase in the error rate to a total loss of data.

The rapid development of communications technologies and networks has made electromagnetic interference and radiation an emerging environmental pollutant. But electromagnetic interference can be eliminated by various measures including strategies such as earthing, galvanic coupling, filters, and shielding. Shielding is particularly effective, but currently used shielding materials can be cumbersome and heavy, limiting how and when they can be used.

Professor Hongli Zhu from Northeastern University in Boston, USA, had perhaps a radical new idea: to create lightweight, magnetic wood for electromagnetic interference shielding.

Her research team used basswood — a porous structured wood — as a lightweight 3D scaffold into which magnetic iron oxide nanoparticles were incorporated. The production process involved the removal of lignin from natural wood followed by mineralization to give the woodblock its electromagnetic shielding properties.

Here, iron oxide nanoparticles firmly attached to the surface of the wood cell walls by alternating incubation cycles with ferrous sulfate and sodium carbonate solutions. According to Zhu, “The biggest difficulty [in this step] is to uniformly grow the magnetic materials inside the wood”. Nevertheless, the obtained magnetic wood is much lighter than traditional-used magnetic metals and construable for versatile applications.

Although Zhu sees the most promising application for defense and information security protection, this work provides an inspiring strategy to develop sustainable, lightweight, and environmentally friendly wood for multi-functional magnetic applications.

Reference: Z. Cheng, et al., ‘Lightweight and Construable Magnetic Wood for Electromagnetic Interference Shielding.’ Advanced Engineering Materials (2020). DOI: 10.1002/ adem.202000257