Innovative ferrofluidic inertial sensor exploiting the Rosensweig effect

In this work a novel inertial sensor is presented, which can be used as a low band accelerometer, a vibration sensor or an inclinometer. The device consists of a glass plate filled with deionized water surrounding a small volume of ferrofluid; a permanent magnet is used to fix the position of the ferrofluidic mass in a compliant position. The effect of an external stimulus can be estimated by measuring the perturbation produced on the ferrofluidic mass. The static friction effect is overcame by exploiting the Rosensweig effect, caused by the magnetic field acting on the ferrofluid and producing spikes whose position is linked to the quantity to be measured. The action of the forcing quantity on the spike position is monitored by the use of two external planar coils. In the proposed device the electric read-out system is decoupled from the mechanical transducer; this makes the prototype low cost and suitable for real applications.