Microstrip Patch Sensor for Characterizing Saline Solution Based on Complimentary Split-Ring Resonators (SC-SRRs).

Area of Science:

• Electromagnetics
• Sensor Technology
• Materials Science

Background:

• Complex permittivity is crucial for characterizing liquids.
• Microstrip patch sensors offer non-contact measurement capabilities.
• Saline solutions require accurate permittivity determination for various applications.

Purpose of the Study:

• To develop and validate a novel microstrip patch sensor for measuring the complex permittivity of saline solutions.
• To investigate the sensor's performance across a salinity range of 0 to 100 ppt.
• To establish numerical equations for predicting conductivity, dielectric constant, and concentration.

Main Methods:

• Design of a microstrip patch sensor with four single complementary split-ring resonators (SC-SRR).
• Utilizing a high-frequency structure simulator (HFSS) for sensor design.
• Fabrication using a computer numerical control (CNC) machine and FR-4 substrate with a Teflon box.
• Operation based on the turbulence technique, analyzing resonant properties (resonant frequency, reflection coefficient S11, quality factor Q).

Main Results:

• The sensor demonstrated high sensitivity in non-contact and non-destructive measurements.
• Measurement and simulation results showed excellent agreement with theoretical models (Klien and Meissner, Debye models).
• Derived numerical equations for conductivity, dielectric constant, and concentration showed good agreement with experimental data.

Conclusions:

• The proposed SC-SRR microstrip patch sensor is effective for determining the complex permittivity of saline solutions.
• The sensor's performance indicates suitability for agricultural (freshwater identification) and medical (salinity detection in biological fluids) applications.
• The sensor provides a reliable method for analyzing mixed liquids and identifying diseases based on salt concentration.