Real-time monitoring of water contaminants for situation awareness using electromagnetic field sensing system

Abstract

Up to 70,000 known and emerging chemical, biological, and radiological contaminants may be present in various water resources. To assure the safety and quality of water and to guarantee the situational awareness of safe water supplies, efficient real-time measurement methods with superior sensitivity are required. Current measurement methods of pollutants are mostly based on off-line monitoring which implies low frequency data sampling, delays between sampling and results, and additional chemical use. In this study, a novel sensing system where the interaction of the electromagnetic field with the tested fluid reveals its composition is presented. In particular, it is suggested that microwave based sensors are a suitable technology to fulfill the requirement for a real-time water pollution monitoring platform. A prototype microwave sensor in the form of printed Cu pattern on FR4 substrate was designed and tested for its response to air, deionized water, 500 ppm phosphate solution, and cooking oil samples. This sensor operates based upon the interaction of the electromagnetic waves and the material under test, which manifests itself as a unique spectra as measured for each sample due to its specific permittivity. By considering how the reflected microwave signal (in a form of S11 parameter) varies at discrete frequency intervals, the change in the signal can be linked to the composition of the object under test. © 2013 Springer Science+Business Media Dordrecht.