Flexible and anisotropically conductive film by assembly of silicone rubber and cobalt-coated glass fiber composites

In this study, we prepared electromagnetic cobalt-coated glass fiber (Co@GF) composites via an electroless plating method. Subsequently, a conductive sandwich flexible film consisting of Co@GF composites and liquid silicone rubber (RTV-2) was successfully formed using the tape casting method at room temperature. Based on the perfect coating and excellent electrical conductivity of the Co@GF composites, the resultant RTV-2/Co@GF/RTV-2 sandwich flexible film showed a low volume resistivity of 0.264 Ω·cm and could stretch to 100% (of 4.40 Ω·cm) without obvious fracture. When a magnetic field was applied during the curing process, the electromagnetic Co@GF composites were aligned automatically in the RTV-2 matrix because of their ferromagnetic nature. The as-prepared film exhibited anisotropy in its electrical performance. The volume resistivity parallel to the magnetic field direction is approximately two times lower than that in the perpendicular direction. The maximum difference in the volume resistivity (ρ∥ = 0.768 Ω·cm and ρ⊥ = 1.549 Ω·cm) was obtained at a magnetic field intensity of 800 mT. In addition, a magnetic field intensity of 100 mT helps improve the electrical conductivity of the as-obtained sandwich film. The anisotropic RTV-2/Co@GF/RTV-2 sandwich flexible film is considered a promising flexible electronic sensor, where discrepant inductive sensitivity is required in orthogonal directions.