Porous and anisotropic liquid metal composites with tunable reflection ratio for low-temperature electromagnetic interference shielding. (June 2020)

• Record Type: Journal Article
• Authors: Zhang, Mingkuan; Zhang, Pengju; Zhang, Chenglin; Wang, Yushu; Chang, Hao; Rao, Wei
• Is Part Of: Applied materials today. Volume 19(2020)
• Publication Date: 2020-06
• Subjects: Electromagnetic-interference shielding -- Liquid metal -- Cryogenic -- Adjustable reflection; Materials science -- Periodicals; Materials -- Research -- Periodicals; 620.1105
• DOI: 10.1016/j.apmt.2020.100612
• Languages: English
• ISSNs: 2352-9407

Abstract

Graphical abstract: Highlights: Porous and anisotropic liquid metal composites (named LTSMs) have been fabricated to realize cryogenic electromagnetic shielding. The conductivity of LTSMs increases dramatically after the liquid-solid phase change of liquid metal. The shielding effectiveness at 77 K can reach ∼80 dB that is superior than that at 300 K (∼20 dB) in 8–12 GHz. The ratio of reflection of LTSMs could be regulated through adjusting the direction of electromagnetic waves and the environment temperature. Abstract: Materials providing electromagnetic interference (EMI) shielding at low temperature are highly desirable for cryogenic electronic equipment. However, the structure of conventional shielding material may be affected by thermal stress at cryogenic conditions, which is harmful to their shielding performance. Here, we demonstrate the potential of a porous and anisotropic gallium-indium-alloy (liquid metal) based composite as low-temperature shielding materials (LTSMs). LTSMs at 77 K exhibited EMI shielding effectiveness of ∼80 dB, which is superior to that at 300 K (∼20 dB) in 8–12 GHz. This upsurge mainly originates from the newly-formed conductive path induced by expansile liquid metal particles after the liquid-solid phase change. Besides, the porous structure and anisotropy of conductivity offered by LTSMs enable them to alter the reflection coefficient from 40% to 85% by adjusting the direction of incident electromagnetic waves. This adjustable material provides a new option for shielding protection, especially at the cryogenic conditions.