Electromagnetic shielding with graphene-based sandwich structures

(Nanowerk News) Researchers have demonstrated a series of graphene-based sandwich structures that were fabricated by assembling graphene films and various spacers.
The results, reported in ACS Applied Materials & Interfaces ("Graphene-Based Sandwich Structures for Frequency Selectable Electromagnetic Shielding"), suggest that the sandwich structures enable effective EMI shielding performance greater than 20 dB in the X-band.
Two-layer sandwich structures with various graphene films and EMI shielding performance
Two-layer sandwich structures with various graphene films and EMI shielding performance: schemes from the cross-section view of (a) GO-D-GO, (b) GN-D-GN, (c) GO-D-GN, and (d) GN-D-GO sandwich structures; (e) total SE, (f) SE absorption, and (g) SE reflection of the corresponding sandwich structures. Note that the illustrated electromagnetic waves in the schemes are not to scale, and green and pink waves in the schemes indicate the transmittance and reflected waves, respectively. (© ACS) (click on image to enlarge)
Electromagnetic (EM) signals lead to electromagnetic emission and interference in the communicating apparatus, which is considered a significant concern in the advanced electronic and telecommunication industries.
To addres these issues, a variety of lightweight materials with electromagnetic interference (EMI) shielding properties have been developed to meet the requirements in the current industries. In addition to traditional copper, carbon materials (carbon nanotubes, graphene, and carbon filers) that have delocalized π electronic networks have drawn significant attention in the scientific communities because the unique advantages in electrically conductive carbon are ideal to allow for achieving the EMI shielding materials with exclusive characteristics.
Graphene appears to be the most effective material for EMI shielding and previously, researchers already demonstrated that single-layer graphene is an excellent choice of material for high-performance EMI shielding.
In this new work, a research team in China proposes novel sandwich structures for manipulating the EM wave transport, which holds unique EMI shielding features of frequency selectivity. By employing electrical and magnetic loss spacers, the resultant sandwich structures are endowed with tunable EMI shielding performance, showing substantial improvements in overall shielding effectiveness along with pronounced shielding peak shift.
"Compared to the conventional uniform bulk and thin-film shielding materials, the sandwich structures were able to present unique frequency selectivity owing to employment of the resonance features," the authors conclude their report. "Further improvements could be achieved via tuning spacers with either electrical loss or magnetic loss properties, which highlight an exclusive platform for designing advanced EMI shielding materials."
Michael Berger By – Michael is author of three books by the Royal Society of Chemistry:
Nano-Society: Pushing the Boundaries of Technology,
Nanotechnology: The Future is Tiny, and
Nanoengineering: The Skills and Tools Making Technology Invisible
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