Key Takeaways & Executive Findings
- •• A novel LM/CIP/PDMS composite with core-shell structure combines magnetic and dielectric properties for enhanced EMW absorption. • The addition of EGaIn liquid metal improves mechanical flexibility and introduces dielectric loss mechanisms, overcoming the limitations of pure magnetic CIP fillers. • Mechanical strain induces the formation of a conductive LM network, further enhancing EMW absorption performance. • The composite offers a promising solution for flexible, stretchable EMW-absorbing materials to mitigate electromagnetic pollution in advanced wireless technologies.
Abstract
The advancement of wireless technologies has increased the global demand for ubiquitous connectivity. However, this surge has increased electromagnetic pollution. This study introduces a composite comprising a polymer matrix (polydimethylsiloxane, PDMS) and a magnetic filler (carbonyl iron powder, CIP) to effectively absorb electromagnetic waves (EMW) and suppress electromagnetic noise, while exhibiting good mechanical properties. Eutectic gallium–indium (EGaIn) liquid metal (LM) was introduced to improve the insulating properties of magnetic fillers. A core–shell structure was obtained by coating the CIP particles with EGaIn, thereby combining magnetic and dielectric materials to enhance EMW absorption. The fluid characteristics of the LM improved the mechanical properties, whereas its electrical conductivity enhanced interfacial polarization loss, thereby augmenting the dielectric loss value of the composites. Moreover, the application of mechanical strain enhanced the EMW absorption of the LM/CIP/PDMS composites due to the formation of a conductive LM network.
1. Introduction
With the recent expansion of Internet of Things, wireless devices, wearable electronics, and smart sensors have been widely used in day-to-day activities [1–2]. Although this rapid technological advancement has greatly improved the standard of living, the spread of Internet on Things based on wireless communication caused the increase in risk of electromagnetic (EM) pollution [3], which negatively affects the operation of nearby electronic devices [4–5]. This problem is expected to exacerbate as the industry continues to expand 5G and 6G mobile networks [6]. Therefore, materials to efficiently absorb electromagnetic wave (EMW) have attracted considerable attention to reduce EM pollution [7–9].
EM materials can be divided into two categories based on the absorption-to-reflection ratio, namely EMW-shielding and EMW-absorbing materials [10]. EMW-shielding materials block EM radiation by reflecting most EMWs. However, this can result in undesirable secondary pollution and disrupt the stable operation of neighboring electrical components. In contrast, EMW-absorbing materials attenuate and absorb incident EMWs and convert them to heat. Such materials are used in developing highly integrated packaging devices due to they prevent undesirable secondary pollution [11].
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Haeji Kim, Philippe Tassin, Zungsun Choi, Byungil Hwang (2025). Strain-enhanced liquid-metal-coated carbonyl-iron-powder-embedded polydimethylsiloxane composites for effective electromagnetic wave absorption. Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报). https://doi.org/10.1007/s12613-024-3055-9
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Frequently Asked Questions
What is the main innovation of this study?
The study introduces a composite material that combines carbonyl iron powder (CIP) with eutectic gallium-indium (EGaIn) liquid metal in a polydimethylsiloxane (PDMS) matrix, creating a core-shell structure that enhances electromagnetic wave absorption through both magnetic and dielectric loss mechanisms.
How does mechanical strain affect the electromagnetic wave absorption?
Applying mechanical strain to the LM/CIP/PDMS composite induces the formation of a conductive liquid metal network, which increases the dielectric loss and thereby enhances the electromagnetic wave absorption performance.
What are the advantages of using liquid metal in this composite?
The liquid metal (EGaIn) improves the mechanical flexibility of the composite and introduces interfacial polarization loss due to its electrical conductivity, which augments the dielectric loss and overall EMW absorption capability.
What is the significance of the core-shell structure?
The core-shell structure, where CIP particles are coated with EGaIn, combines magnetic and dielectric materials, allowing for synergistic effects that enhance electromagnetic wave absorption compared to using CIP alone.
What are the potential applications of this material?
This material is suitable for use in flexible and stretchable electronic devices, wearable technology, and electromagnetic interference shielding applications, where effective EMW absorption and mechanical flexibility are required.
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