Effect of magnetic field intensity and γ-Fe2O3 nanoparticle additive on electrical conductivity and viscosity of magnetorheological carbonyl iron suspension-based membranes

Smart membranes based on an absorbent cloth microfiber material and silicone oil were prepared using a fixed volume concentration of carbonyl iron and various volume concentrations of additive nanoparticles. The membranes were then used to manufacture magnetoresistors, whose resistance was measured under an applied magnetic field with a magnetic flux density up to 250 mT. The electrical conductivity and viscosity of the membranes increased with increasing magnetic field intensity, while at a fixed magnetic field strength, the electrical conductivity and viscosity decreased with increasing concentration. A theoretical model to explain these results was developed further in the framework of a dipolar approximation.