A Voltage‐Boosting Strategy Enabling a Low‐Frequency, Flexible Electromagnetic Wave Absorption Device

Abstract

Nowadays, low-frequency electromagnetic interference (<2.0 GHz) remains a key core issue that plagues the effective attenuation performance of conventional absorption devices prepared via the component-morphology method (Strategy I). According to theoretical calculations, one fundamental solution is to develop a material that possesses a high ε' but lower ε″. Thus, it is attempted to control the dielectric values via applying an external electrical field, which inducts changes in the macrostructure toward a performance improvement (Strategy II). A sandwich-structured flexible electronic absorption device is designed using a carbon film electrode to conduct an external current. Simultaneously, an absorption layer that is highly responsive to an external voltage is selected via Strategy I. Relying on the synergistic effects from Strategies I and II, this device demonstrates an absorption value of more than 85% at 1.5-2.0 GHz with an applied voltage of 16 V while reducing the thickness to ≈5 mm. In addition, the device also shows a good absorption property at 25-150 °C. The method of utilizing an external voltage to break the intrinsic dielectric feature by modifying a traditional electronic absorption device is demonstrated for the first time and has great significance in solving the low-frequency electromagnetic interference issue.

A Flexible Microwave Shield with Tunable Frequency‐Transmission and Electromagnetic Compatibility

“…Currently, multiple‐component systems primarily contain graphene‐based composites (graphene/oxide), a semiconductor heterojunction (e.g., ZnO/ZnS, SnO 2 /SnS, etc. ), and metal/metal oxides . However, shielding coefficient of graphene‐based composites at full X‐band are usually greater than 0.8, which is due to the stronger starting shielding ability of graphene .…”

Enhanced electromagnetic wave absorption of Fe‐doped silicon oxycarbide nanocomposites

“…According to the Debye theory, ε″ can be described as follows: 58 where ε s is the static permittivity, ε ∞ is the relative dielectric permittivity at the high-frequency limit, ω the angular frequency, τ is the relaxation time, and σ is the electrical conductivity. Therefore, increasing the conductive paths could improve the permittivity according to the Equation (5). With increasing the Fe contents, a large number of graphite is exhausted and then leads to reduce the conductive paths within the samples.…”

“…Nowadays, with the rapid development of the radar technology, wearable electronic products and wireless communication, the electromagnetic radiation and interface have already caused serious electromagnetic pollution, as well as military stealth technology. [1][2][3][4][5] Despite numerous works have focused on electromagnetic interface (EMI) shielding materials, the ideal EMI shielding materials with lightweight, high flexibility, thermally and chemically stable with high-efficiency over a broad absorption frequency range are still deemed for engineering. [6][7][8] To achieve such ideal goal, the electromagnetic wave consumed by dielectric loss, magnetic loss and other energy loss mechanisms should be further enhanced.…”

Biomass-Derived Porous Carbon-Based Nanostructures for Microwave Absorption

“…The rapid development of electronic technologies brings about great convenience to humans' life. However, excessive usage of electronics also results in serious electromagnetic (EM) radiation and interference, which is detrimental to human health [1][2][3][4][5]. Consequently, the research on use of functional EM absorbers to eliminate the unwanted EM energies has attracted significant attention.…”