CNT Conductive Epoxy Composite Metamaterials: Design, Fabrication, and Characterization

In this study, carbon nanotube (CNT) epoxy composite films were fabricated, characterized, and tested as resonant, plasmonic metamaterials. CNT-epoxy formulations, containing diverse CNT loadings, were fabricated and templates were used to generate repeating arrays of squares of diverse dimensions. Their absorption characteristics were characterized by collecting free space reflectivity data in the microwave band, using an arch setup in an anechoic chamber. Data were collected from 2 to 20 GHz. The materials behavior was modeled using a standard unit-cell-based finite element model, and the experimental and calculated data were compared. The experimental results were successfully reproduced with appropriate adjustments to relative permittivity of the composite films. This research demonstrates the ability to use CNT-based conductive composites for manufacturing metamaterials, offering a potentially lighter-weight alternative in place of traditional metal films. Lower conductivity than other conductors causes a widening of the absorption curves, providing a wider band of frequency absorption.