Metamaterials, characterized by their unique artificial periodic structures, exhibit extraordinary abilities in controlling electromagnetic waves not found in natural materials. Metamaterial absorbers, for example, have been developed by patterning solid conductive materials on dielectric surfaces. However, the foldability limitations of solid conductors make them unsuitable as foldable metamaterial absorbers since they lose those desirable properties when folded. To address this challenge, various methods using liquid metals have emerged, but they either require often necessitate structural frames or are primarily suited for hard surfaces, limiting their foldability potential. This study proposes an innovative solution involving the deposition of liquid metal onto paper surfaces to overcome foldability constraints. We design a metamaterial absorber with a circular pattern using three sheets of printing paper bonded with a film, leveraging these adhesive properties of oxidized gallium-based liquid metal to waterproof agent coated printing paper while preventing adhesion to laser-printed toner surfaces. The experimental results show that this absorber achieves an absorption rate of more than 90% in the frequency range of 10.36–10.76 GHz while being insensitive to polarization and incidence angle. Surprisingly, our proposed absorber retains its excellent performance even after being folded and unfolded up to 50 times. This foldable metamaterial absorber made of liquid metal is a promising solution for electromagnetic wave management applications requiring flexibility and adaptability.

中文翻译：

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纸上液态金属印刷可折叠超材料吸收器


超材料以其独特的人工周期结构为特征，在控制天然材料中不存在的电磁波方面表现出非凡的能力。例如，超材料吸收器是通过在介电表面上对固体导电材料进行图案化而开发的。然而，固体导体的可折叠性限制使其不适合作为可折叠超材料吸收器，因为它们在折叠时会失去这些理想的特性。为了应对这一挑战，出现了各种使用液态金属的方法，但它们要么通常需要结构框架，要么主要适用于硬表面，限制了它们的可折叠潜力。这项研究提出了一种创新的解决方案，涉及将液态金属沉积到纸张表面以克服可折叠性限制。我们使用三张与薄膜粘合的印刷纸设计了一种具有圆形图案的超材料吸收器，利用氧化镓基液态金属对涂有防水剂的印刷纸的粘合特性，同时防止粘附到激光印刷的碳粉表面。实验结果表明，该吸波体在10.36~10.76 GHz频率范围内实现了90%以上的吸收率，同时对偏振和入射角不敏感。令人惊讶的是，我们提出的吸收器即使在折叠和展开 50 次后仍保持其优异的性能。这种由液态金属制成的可折叠超材料吸收器对于需要灵活性和适应性的电磁波管理应用来说是一种有前景的解决方案。