A flexible polyimide based device for displacement sensing

The goal of this work is to investigate design and fabrication of a passive displacement sensor based on flexible polyimide membrane. Proposed sensor is realized in heterogeneous integration process of Printed Circuit Board (PCB) technology, flexible substrate, and Low Temperature Co-fired Technology (LTCC) ferrite core. The sensor uses the self-resonant frequency modulation of a planar coil by the relative displacement of a ferrite core attached to a polyimide foil. Displacement variations are presented with micrometre translation stage (MTS) and detected by impedance and phase dip modulation. Measurements were performed on Impedance Analyzer (Agilent HP 4191A) and simulation results are in agreement with measurement results. The proposed sensor design has various options and applications in many fields. The realized sensor and its fabrication present several advantages concerning the possibility of direct modification and integration with the corresponding electronics, the simplicity of the process and packaging systems.