LC resonant displacement sensor realized with various designs of meander inductor

Abstract

In this paper we present various configurations of meander inductor and their influence on characteristics of passive LC displacement sensor. Developed LC sensor comprises a fixed meander inductor and a movable module of meander inductor-interdigital capacitor resonant circuit, thereby causing the sensor resonant frequency to be displacement-dependent. Also, it is explained a theoretical model of LC displacement sensor. Sensor circuits have been fabricated in PCB technology. The main goal was to find the optimal position for measurement connection pads on fixed meander inductor PCB as well as position of connection line between meander inductor and interdigital capacitor on PCB board with LC circuit. Measurements were realized on Impedance Analyzer (HP4191A) in frequency range from 10 MHz to 30 MHz, with 100 kHz step. For each configuration of meander inductor phase dip, resistance and impedance modulus were measured. In addition, sensors sensitivity is presented. Achieved sensors sensitivity are 0.45 ̊/μm and 0.29 ̊/μm for both configuration, respectively. As results of these measurements the best configuration and the best sensor sensitivity for both mender inductors was determined. Copyright © 2013 American Scientific Publishers. All rights reserved.