Heterogenous Integrated Displacement Sensor with Grooved Ferrite

Abstract

This paper presents the realization of displacement sensor based on novel ferrite design with grooves and with the use of modern additive technology (hetero integration) for the production of other sensor parts. The three main parts of the sensor are: the inductor, the grooved ferrite disk and the flexible spacer. The planar inductor is realized using a standard Printed Circuit Board - PCB technology. The spacer of the sensor, which allows sensitivity to the action of displacement, is realized using a Ninjaflex filament and a 3D technology. The ferrite disk is fabricated using a M30 powder (Mn0.5Zn0.5Fe2O4), but in the form of a disk with grooves on its surface. Displacement measurement is performed wirelessly using an external coil around the sensor as an antenna. By the action of the displacement on the sensor surface and the approach of the ferrite to the inductor, its inductance increases, which leads to a decrease in the resonant frequency of the antenna-sensor system. The use of a novel ferrite design with grooves improved sensor characteristics, i.e. the high sensitivity of 0.0026 MHz/µm is achieved.