An ultra-strong multilayer structural bacterial cellulose film by biosynthesis for high-performance electromagnetic interference shielding

Abstract

Structural materials represent the future development direction for electromagnetic interference (EMI) shielding materials, enabling the effective integration of multiple functions into a single material. Nonetheless, the traditional assembly processes remain a significant challenge in coordinating the mechanical properties and functionality of structural materials. In this study, we introduce a biological synthesis method for fabricating multilayered electromagnetic interference (EMI) shielding materials using bacterial cellulose (BC), which are developed by entangling AgNWs, CNT, and Fe₃O₄ with continuously secreted cellulose nanofibers during in situ fermentation. The BC/AgNWs and BC/CNT/Fe₃O₄ composites could function as the reflection and absorption layers for electromagnetic waves, respectively, thereby simultaneously achieving superior mechanical performance and electromagnetic wave absorption capabilities. Benefiting from the biosynthesis strategy, the tensile strength of the BC/AgNWs/CNT/Fe₃O₄ multilayer film reached 327 MPa, which is higher than that of almost all previously reported multilayer electromagnetic shielding materials. Meanwhile, multilayer structural design improves impedance matching, contributing to the high EMI shielding performance (69.2 dB) and high absorption effectiveness ratio (83.1%). This study presents a novel strategy for producing multilayer structural materials through in situ biosynthesis, demonstrating significant utility in the field of stealth technology and electromagnetic interference protection for electronic packaging materials.