Aerogel fashioned into world's lightest electromagnetic shielding
Containing the electromagnetic radiation generated by electronic components is a key consideration for designers of electronic devices, but today’s metal-based shielding materials have their downsides. Scientists at the Swiss Federal Laboratories for Materials Science and Technology (EMPA) have developed an new aerogel-based material that blocks a wide range of frequencies, forming what they describe as by far the lightest electromagnetic shielding material in the world.
Blocking the electromagnetic radiation in electronic devices can be critical to maintaining their performance, because if these fields aren’t isolated from their surroundings they can affect signal transmission or the function of nearby electronics. Engineers often turn to thin sheet metals for this task, but these add extra weight to the device and don’t always fit neatly with the design.
The EMPA team has been investigating alternative materials with the hope of producing lighter, more malleable solutions, which led them to cellulose fibers sourced from wood. These were whittled down to nanoscale size and combined with silver nanowires to form a light, porous aerogel that offers “excellent shielding against electromagnetic radiation,” with a density of only 1.7 milligrams per cubic centimeter.
While the composition of the cellulose fibers and silver nanowires produce a shielding effect, the porous nature of the material also plays a role. When the electromagnetic fields encounter the pores, they are bounced around within the void to generate a secondary electromagnetic field, which actually cancels out the original.
The combined effect is a material that blocks virtually all radiation in the 8 to 12 GHz range, according to the team. The desired level of absorption, meanwhile, can be adjusted by tweaking the porosity, number of silver nanowires and thickness of the material.
The team was able to able to make further weight reductions by swapping out the silver nanowires for plates of titanium carbide, which act like “bricks” while the cellulose fibers act as the “mortar.” This combined titanium carbide cellulose aerogel is “by far the lightest electromagnetic shielding material in the world,” according to the team.