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

Paris Velez, Jonathan Munoz-Enano, Katia Grenier, Javier Mata-Contreras, David Dubuc, Ferran Martin

Research output: Contribution to journalArticleResearch

87 Citations (Scopus)


© 2001-2012 IEEE. 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 paper, 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.
Original languageEnglish
Article number8594579
Pages (from-to)2562-2569
JournalIEEE Sensors Journal
Publication statusPublished - 1 Apr 2019


  • Microwave sensors
  • differential sensors
  • electrolyte concentration
  • microfluidics
  • microstrip technology
  • permittivity measurements
  • split ring resonator (SRR)


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