Modeling and Design of Ferrofluidic Sensors

Abstract

Novel inertial sensor based on ferrofluids are presented in this paper. The proposed devices have a widely tunable operative range and high sensitivity. A ferrofluidic sample in aqueous suspension acts as inertial mass. The devices are constituted by one excitation coils and one differential sensing coil wound around a glass pipe where the ferrofluid is contained. The bias magnetic force, induced by the coil, attracts the ferrofluid in its centre thus acting like an equivalent spring. The acceleration to be measured reflects therefore in the inertial mass oscillation amplitudes that are sensed by using a differential transformer whose output voltage is a function of the ferrofluid position. Analytical models, simulations and experimental result are presented to demonstrate the suitability of the proposed approach.