Talanta

Microwave sensors, Chloride detection, Portable detection, Specificity and sensitivity

Accurate detection of chloride ions (Cl−) in water is of great significance for ensuring human health and environmental safety. This study reports a cost-efficient, portable, and flexible microwave sensing system for detecting Cl− in high-salinity water. This system employs a split ring resonator fabricated on a printed circuit board (PCB) substrate as the microwave sensor. The passivation layer covers the sensor to improve the sensitivity, prevent cross-contamination, and increase robustness. The integration of the sensor with a palm-sized LiteVNA for microwave signal acquisition facilitates portable Cl− detection. To avoid the influence of other impurity ions and achieve high specificity in Cl− detection, silver nitrate (AgNO3) is added into the sample during testing. The reaction between Cl− and AgNO3 induces changes in the microwave signal caused by variations in dielectric properties, which corresponds to the Cl− concentration. The detection is carried out over a Cl− concentration range of 0–40 g L−1 within the microwave frequency range of 0.5–3.5 GHz, whereas a characteristic peak appears between 0.9 and 1.2 GHz. The frequency shift before and after AgNO3 addition is proportional to the Cl− concentration and remains unaltered from various impurity ions. The optimized sensor design and AgNO3 amount facilitate the system to obtain high sensitivity, excellent specificity, and rapid detection with a response time of 10 s.

Xiao Liu

Ning Qin,Pei Zhao,Yong Dong

Chonghui Yang,Xiangwen Xing,Guiqin Yang,Gang Ding,Qinglong Sun,Zhanlong Song

Journal paper

129434

302

6.1

No

2026-01

SCI