Ferrofluid transformer-based tilt sensor

Abstract

This paper investigates utilizing ferrofluid in a novel design for a tilt sensor. Ferrofluid is becoming widely used in various fields such as sealing, heat transfer and damping, and its popularity is increasing due to its ability to function as both a fluid and a magnetized substance. The proposed sensor design employs the movement of an excited ferrofluid through a transformer setup which detects the induced voltage in a sensing coil due to tilting of the device. The movement of the ferrofluid is caused by the mechanical force created by the swinging of a non-magnetic mass. As the device tilts, it causes the mass to swing in the direction of tilt. The mass is attached directly to a flexible tube containing ferrofluid and pulls the tube through a set of rollers, squeezing the ferrofluid towards the sensing coil. The voltage readings in the sensing coil are used to determine the tilt angle of the device. The device varies from previous designs by incorporating the mechanical force exerted to the ferrofluid from rollers due to titling of the mass. This mechanical force helps overcome the attraction force between the excited coil and the ferrofluid. The device was fabricated and characterized within the range of 0°–70° angle of tilt. The leakage of the ferrofluid through the gap between the rollers was evaluated and no sign of a leakage was observed.