Microwave

Engineering

Materials science

Chromatography

Fluidics

Telecommunications

Solvent

Computer science

Acoustics

Split-ring resonator

Physical chemistry

Physics

Organic chemistry

Electronic engineering

Resonator

Sensitivity (control systems)

Analytical Chemistry (journal)

Optical ring resonators

Chemistry

Electrode

Electrolyte

Optoelectronics

Electrical engineering

Ring (chemistry)

IEEE Sensors Journal

A differential microwave sensor, based on a pair of uncoupled microstrip lines each one loaded with a split ring resonator (SRR), is applied to the measurement of electrolyte concentration in deionized (DI) water.For that purpose, fluidic channels are added on top of the SRR gaps, the most sensitive parts of the structure.The operating principle is based on the measurement of the cross-mode insertion loss, highly sensitive to small asymmetries caused by differences between the reference liquid and the liquid under test (LUT).In this work, the reference liquid is pure DI water (the solvent), whereas the solution, DI water with electrolyte content, is injected to the LUT channel.The proposed sensor is able to detect electrolyte concentrations as small as 0.25 g/L, with maximum sensitivity of 0.033 (g/L) -1 .The sensor is validated by measuring the concentration of three types of electrolytes, i.e., NaCl, KCl and CaCl2.Finally, the sensor is applied to monitor variations of total electrolyte concentration in urine samples.

Split Ring Resonator-Based Microwave Fluidic Sensors for Electrolyte Concentration Measurements