Empa scientists have created the world’s lightest shielding material to protect next-gen microelectronics from electromagnetic radiation.
The scientists led by Zhihui Zeng and Gustav Nyström were able to achieve this by using nanofibers of cellulose as the basis for an aerogel.
They then produced a composite of cellulose nanofibers and silver nanowires, creating ultra-light fine structures which provide excellent shielding against electromagnetic radiation and interference.
According to the scientists, the effect of the material is impressive: with a density of only 1.7 milligrams per cubic centimeter, the silver-reinforced cellulose aerogel achieves more than 40 dB shielding in the frequency range of high-resolution radar radiation (8 to 12 GHz).
This implies that the new shielding material can intercept all radiation in this frequency range.
Apart from the composition of cellulose and silver wires, the pore structure of the material is also equally important for creating an effective electromagnetic shield.
To create pores of optimum size and shape, the scientists poured the material into pre-cooled molds and allowed it to freeze out slowly.
The growth of the ice crystals creates the optimum pore structure for damping the fields. What’s more, the damping effect can even be specified in different spatial directions.
For instance, if the material freezes out in the mold from bottom to top, the electromagnetic damping effect is weaker in the vertical direction.
In the horizontal direction, the damping effect is optimized. Shielding structures cast in this way are highly flexible: even after being bent back and forth a thousand times, the damping effect is practically the same as with the original material.
The desired absorption can also be easily adjusted by adding more or less silver nanowires to the composite, as well as by the porosity of the cast aerogel and the thickness of the cast layer.
In another experiment, the Empa team removed the silver nanowires from the composite material and connected their cellulose nanofibers with two-dimensional nanoplates of titanium carbide.
This was done through a special etching process, and the nanoplates acted like hard ‘bricks’ that are joined together with flexible ‘mortar’ made of cellulose fibers.
According to the scientists, this titanium carbide nanocellulose aerogel is currently the world’s lightest electromagnetic shielding material ever.
Image and content: Empa