Multifunctional Ultrahigh Sensitive Microwave Planar Sensor to Monitor Mechanical Motion: Rotation, Displacement, and Stretch

Abstract

This paper presents a novel planar multifunctional sensor that is used to monitor physical variations in the environment regarding distance, angle, and stretch. A double split-ring resonator is designed at 5.2 GHz as the core operating sensor. Another identical resonator is placed on top of the first one. The stacked configuration is theoretically analyzed using an electric circuit model with a detailed parameter extraction discussion. This design is first employed as a displacement sensor, and a compelling high sensitivity of 500 MHz/mm is observed for a wide dynamic range of 0-5 mm. Then, in another configuration, the stacked design is used as a rotation sensor that results in a high sensitivity of 4.5 MHz/ ° for the full range of 0-180 ° . In addition, the stacked resonator is utilized as a strain detector, and a 0–30% stretch is emulated with a linear sensitivity of 12 MHz/%. Measurements are well in congruence with simulated results, which proves the accurate functionality of the sensor in tracking mechanical deformations, all in a single compact contraption.

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.…”

A Reflective-Mode Phase-Variation Displacement Sensor

“…It can be appreciated that in the coupling modulation sensors [8], [9], [13], pulsecounting sensors [21], [22], as well as in the sensors reported in this work (sensors A, B and C), the required signal for sensing is a single-tone (harmonic) signal, this representing a clear advantage over the frequency-variation sensors [1], [2], [5], [6], as discussed before. Concerning sensor resolution, it has been considered that for the frequency variation sensors [1], [2], [5], [6], the system is able to discern frequency variations of 10 MHz (an optimistic value), thereby providing the input resolution values given in the table. For the coupling modulation sensors, the input resolution has been inferred by considering that 3 dB in the output variable (a transmission coefficient) can be discerned.…”

“…There are several strategies for the measurement of linear and angular displacements using microwaves. One of such strategy exploits frequency variation, where, typically, the relative motion between the static and the movable part of the sensor perturbs the resonance frequency (the output variable) of a planar resonant element [1]- [6]. One of the main limitations of frequency variation sensors (as such sensors are usually referred to) is the requirement of a wideband signal for measuring purposes.…”

Design of Double-Layer Electrically Extremely Small-Size Displacement Sensor

“…Moreover, the subwavelength-size characteristic of metamaterial elements is conducive to the integration and miniaturization of sensors. Owing to these advantages, metamaterials-based sensors have been developed rapidly, and their applications are becoming more and more diversified, including biological component sensor [ 1 ], gas concentration sensor [ 2 ], liquid content sensor [ 3 ], angular displacement sensor [ 4 , 5 , 6 ], displacement sensor [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ], and permittivity sensor [ 16 ].…”

“…Figure15. Schematic view of (a) the magnetic excitation generated by feeding structure and (b) the surface charge distribution and their corresponding surface current distribution for top-layer SRR and bottom-layer SRR of the bidirectional displacement sensor, respectively.…”