Resonant Ferrofluidic Inclinometers

In this paper modeling, prototyping and preliminary characterization of an innovative inclinometer based on ferrofluid is presented. It consists of a glass pipe where a drop of ferrofluid is contained in a water environment, a "retention coil" used to apply an elastic force to the ferrofluidic drop, a "differential sensing coil" to detect the ferrofluidic mass position and two "excitation supplementary coils" to drive the ferrofluidic mass within the water at its mechanical resonant frequency. The device exhibits a tunable operating range, valuable metrological features and an intrinsic robustness against inertial shocks. The proposed solution represents a significant improvement with respect to previous devices proposed by the same authors, in this case resonance is exploited in order to avoid static friction and therefore to enhance resolution, but also to improve sensitivity and linearity. Some experimental results are reported in this paper together with the description of the sensor prototype.