A novel accelerometer based on the first kind of ferrofluid levitation principle

In this paper, a novel accelerometer exploiting the first kind of ferrofluid levitation principle is presented. The device consists of a piston-shaped container filled with ferrofluid surrounding a nonmagnetic insulating rod, which has the same shape as the container and is regarded as an inertial mass. Two annular magnets outside the container are used to create a non-uniform magnetic field which generates a powerful restoring force acting on the nonmagnetic rod. Under the influence of the external acceleration, two coils can detect the change of the volume distribution of the ferrofluid and transmit the voltage signal, which is proportional to the displacement of the nonmagnetic rod. The determination of the working range, linearity and sensitivity depends on the restoring force, thus these factors affecting the restoring force are sufficiently investigated by calculation and experiment. Furthermore, the comparison between numerical calculations and experimental measurements shows a good agreement. The static characteristics of the accelerometer are obtained by using an optimized structure.