Document Type


Publication Date



Institute of Electrical and Electronics Engineers

Source Publication

IEEE Transactions on Instrumentation and Measurement

Source ISSN



Microwave measurements and machine learning algorithms are presented to estimate metal ion concentrations in drinking water. A novel block loop gap resonator (BLGR) as a microwave probe is designed and fabricated to estimate Pb ion concentrations in city water as low as 1 ppb with an rms error of 0.18 ppb. No physical contact between the BLGR probe and the water sample allows on-site/in situ continuous detection of ppb-level metal ion concentrations. The S11 raw data (amplitude and phase) from the BLGR are used to classify and estimate metal ion concentrations using a support vector regression algorithm. The performance of the proposed method to estimate Pb concentrations in the presence of interfering metal ions (Cu 2+ , Fe 3+ , and Zn 2+ ) is also evaluated, and it is found that the average measurement error remains less than 13%.


Accepted version. IEEE Transactions on Instrumentation and Measurement, Vol. 70 (September 23, 2021): 9513909. DOI. © 2021 Institute of Electrical and Electronics Engineers. Used with permission.

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