Performance analysis of a flexible polyimide based device for displacement sensing

Abstract

In this work, two variations of the displacement sensor, based on the heterogeneous integration process of traditional fabrication technologies PCB (Printed Circuit Board) and LTCC (Low Temperature Co-fired Technology) with a flexible polyimide foil are presented. The proposed sensor uses the coil as an essential part, spacer and a polyimide foil as a flexible membrane with a piece of ferrite attached to it. With the displacement of the polyimide foil, the ferrite gets closer to the coil causing an increase in its inductance and a decrease of the resonant frequency of the system (coil, ferrite and antenna). Simulation results showed that sensors with equal outer dimensions but different internal structures exhibit different performances. Two prototypes of the sensor with different ferrite dimensions are designed, fabricated and characterized. Finally, their performances are compared.