Microwave microstrip ring resonator as a paper moisture sensor: study with different grammage

Abstract

This paper reports use of a nondestructive, miniaturized, microwave microstrip ring resonator for moisture sensing application in papers. Advantages offered by this sensor over the prevailing sensors are room-temperature operation, response time in milliseconds, measurements unaffected by dusty environment and ionic conductivity of samples. Samples of eleven types were tested, with grammage (grams per square metre) and thickness varying from 21 to 70 g m −2 and 24 to 80 µm respectively. The wet basis moisture normalization (with respect to instantaneous moisture content in the sample) was established to remove scatter and to bring out clearly grammage dependence, thus avoiding error in moisture prediction due to density variations, using only scalar measurements. A single equation for f r variations is realized in terms of grammage and normalized percentage moisture (M ww ) which is valid for all types of tested paper. A model of the wet paper is suggested mainly based on water-dry paper interaction, also considering parameters like thickness and surface roughness, to explain trends of the sensitivity curves. The estimated %M ww shows an error of ±0.9% in the estimated value as compared to the actual value.

Transmission Lines Loaded With Bisymmetric Resonators and Their Application to Angular Displacement and Velocity Sensors

“…The key is the linear dependence of the net magnetic flux penetrating the loops. Notice that the assumed uniform in (6), (7), and (10) will depend on the spatial location of the resonator so that it decreases with the physical distance (given by the substrate thickness ) between the coupled elements. In the limiting case, and , (10) can be expressed as [26], where is the fraction of the loops that lies beneath the slots.…”

“…In particular, split ring resonators (SRRs) [2], and other related particles, have been exhaustively used for sensing purposes due to their small electrical size and high-factor at the fundamental resonance. Different kind of sensors based on SRRs have been proposed, such as thin-film sensors [3], particle detectors [4], [5], stress sensors [6], moisture sensors [7], pressure sensors [8], displacement sensors [9], [10], or sensors for organic tissue analysis [11].…”

High resolution microwave microstrip resonator for sensing applications

“…Microwave split-ring resonators have recently gathered a lot of attention because of their potential applications in sensing [1][2][3][4][5][6][7][8][9][10][11]. These microwave devices have a planar structure and can be fabricated using a simple process.…”

Configurations of Splitter/Combiner Microstrip Sections Loaded with Stepped Impedance Resonators (SIRs) for Sensing Applications

“…Many of these sensors are based on the variation of the resonance frequency, phase or quality factor of a resonant element, caused by the variable to be sensed [1,2,3,4,5,6,7,8,9]. Among them, there are sensors implemented by loading a transmission line with planar resonators coupled to it [8,9].…”