A Magnetic Fluid-Based Inclinometer Embedding an Optical Readout Strategy: Modeling and Characterization

In this article, a novel inclinometer exploiting a magnetic fluid as the inertial mass and an optical readout strategy is addressed. In particular, the device behavior has been modeled and experimentally observed by means of a dedicated set-up. The proposed inclinometer uses a 5-mm diameter glass pipe filled with water and a drop of ferrofluid (FF), a retaining mechanism based on a permanent magnet and an infrared (IR) readout strategy. The latter is used to measure the position of the inertial mass inside the pipe, which strictly correlated with the sensor inclination. The main outcomes of the proposed sensing solution consist of the use of a passive restoring mechanism and an IR sensing strategy, which are convenient in terms of power budget with respect to sensors exploiting an electromagnetic readout strategy and a powered restoring mechanism acting on the inertial mass. The developed lab-scale prototype exhibits an operating range of +/- 15 degrees, a responsivity of 0.56 V/degrees, and a resolution of 0.25 degrees, as well as a span-to-threshold value of 120.