Electrical anisotropy and multidimensional pressure sensor of aligned Fe3O4@silver nanowire/polyaniline composite films under an extremely low magnetic field

Abstract

A low magnetic field is preferred in preparing aligned composites since a high magnetic field may be harmful to human health. In this study, fine-sized Fe₃O₄ nanoparticles with diameters of several nanometers are decorated on the surface of Ag-NWs (Fe₃O₄@Ag-NWs). Controllably aligned Fe₃O₄@Ag nanowire (Ag-NW)/polyaniline (PANI) composite films are then prepared under an extremely low magnetic field of 26–42 mT, which is much lower than those reported previously (0.1–10 T). As a result, the as-prepared Fe₃O₄@Ag-NW/PANI composite films show an excellent electrical conductivity from 5.5 × 10² to 4.1 × 10³ S cm⁻¹ and a controllable electrical conductivity anisotropy from 1.1 to 6.7. Furthermore, the anisotropic responsive behavior of the Fe₃O₄@Ag-NW/PANI composite film makes it an ideal candidate for the fabrication of multidimensional pressure sensors. In most studies, conventional strain sensors are fabricated because they are only capable of detecting strains in one single direction due to a strongly coupled electrical conductance change. Finally, the fabrication of a multidimensional pressure sensor based on the as-prepared Fe₃O₄@Ag-NW/PANI composite film is demonstrated for the first time and a unique anisotropic pressure sensitivity is reported.