Frequency-Selective EMI Shielding Using PVDF/NiFe ₂ O ₄ //PVDF/Graphene Layered Structure

The increasing complexity of our electromagnetic environment is driving a growing demand for flexible, frequency-selective electromagnetic interference (EMI) shielding materials. Herein, we adopt a simple and cost-effective approach to fabricating layered structures consisting of a conducting (7 mL graphene nanoplatelet-coated PVDF) layer and a magnetic (NiFe2O4-coated PVDF) layer. In this sample series, the composition of the conducting layer is fixed while the concentration of NiFe2O4 ink increases from 5 to 40 mL in the magnetic layer. The EMI shielding properties of these layered structures largely hinge on the thickness of the magnetic layer, resulting in a distinctive frequency selectivity. The shielding efficiency for absorption far exceeds reflection (≤5 dB) at the resonant frequencies, 9 and 11.3 GHz, for all samples. Consequently, the total shielding efficiency (SET) also peaks at the resonant frequencies. It attains a robust value of 53 dB at 9 GHz and 30 dB at 11.3 GHz for the layered structure containing 10 mL NiFe2O4-coated PVDF (L-NF10). The shielding results are further validated using COMSOL Multiphysics RF module. It also predicts the electric and magnetic field distribution in L-NF10 and electromagnetic power dissipation within each layer. This study introduces an effective strategy for developing layered structures with promising frequency-selective EMI shielding behavior that can be extended to multilayer films by simply modulating the number and order of layers.