Planar Phase-Variation Microwave Sensors for Material Characterization: A Review and Comparison of Various Approaches

Abstract

Planar phase-variation microwave sensors have attracted increasing interest in recent years since they combine the advantages of planar technology (including low cost, low profile, and sensor integration with the associated circuitry for post-processing and communication purposes, among others) and the possibility of operation at a single frequency (thereby reducing the costs of the associated electronics). This paper reviews and compares three different strategies for sensitivity improvement in such phase-variation sensors (devoted to material characterization). The considered approaches include line elongation (through meandering), dispersion engineering (by considering slow-wave artificial transmission lines), and reflective-mode sensors based on step-impedance open-ended lines. It is shown that unprecedented sensitivities compatible with small sensing regions are achievable with the latter approach.

A High-Resolution Reflective Microwave Planar Sensor for Sensing of Vanadium Electrolyte

“…They provide regions that are highly sensitive to capacitive and resistive variations in the surrounding environment [ 12 ]. These metamaterial-inspired particles are used in liquid characterization [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ], gas sensing [ 24 ], mechanical deformation sensing [ 25 ], temperature sensing [ 26 , 27 ], etc. However, they suffer from low-to-moderate quality factors that limit their applications to low-loss material sensing.…”

Microwave Planar Resonant Solutions for Glucose Concentration Sensing: A Systematic Review

“…Planar sensors based upon the measured phase-shift for tracking the glucose concentration have also been reported in the literature, although sparingly. These sensors have been proposed for multiple applications requiring the measurement of the dielectric properties of the MUT [151]. These sensors show the advantage of requiring very narrow band interrogation signals (even a single tone in some cases), and the associated driving electronics become simpler and more cost-effective.…”

The Automatic Design of Multimode Resonator Topology with Evolutionary Algorithms

“…Microwave sensors based on microstrip resonators [23] are used for measuring complex permittivity of materials, dielectric measurements of solids and liquids [24][25][26], gas sensing [15], non-invasive medical measurements [26][27][28][29] and other applications [30][31][32]. Permittivirt measurement methods of dielectric materials available in sheet, liquid, paste, powder, etc., forms by microwave resonators used as sensors were summarized in [33,34].…”