A ferrofluid inclinometer with a Time Domain Readout strategy

In this paper a tilt sensor exploiting the effect of the imposed tilt on a mass of ferrofluid free to slide along a glass channel is presented. The proposed inclinometer consists of a 10 mm diameter pipe containing a 0.25 ml of ferrofluid, an actuation coil to control the ferrofluid mass movement and two sensing coils to monitor its position. The actuation and the sensing coils are wound around the pipe and the length of the actuation/sensing system is 78 mm. The novelty of this device, as respect to solutions already presented in the literature, consists in the conversion of the device tilt into the time elapsed between transitions of the ferrofluid mass in two fixed positions inside the channel. This Time Domain Readout strategy allows to implement a device with a frequency output which can be intended as the main advantage of the solution proposed. (C) 2013 Elsevier B.V. All rights reserved.