Jung, Dae-Hyun Kim, Hak-Jin Kim, Joon Yong Park, Soo Hyun Cho, Woo Jae 2024-01-19T15:02:09Z 2024-01-19T15:02:09Z 2022-01-25 2021-04 1424-8220 https://pubs.kist.re.kr/handle/201004/117159 The detection of nitrate pollutants is a widely used strategy for protecting water sources. Although ion-selective electrodes (ISEs) have been considered for the determination of ion concentrations in water, the accuracy of ISE technology decreases owing to the signal drift and decreasing sensitivity over time. The objectives of the present study were: (1) to develop an online water monitoring system mainly consisting of an Arduino board-based Internet-of-Things (IoT) device and nitrate ISEs; and (2) to propose a self-diagnostic function for monitoring and reporting the condition of the ISEs. The developed system communicates with the cloud server by using the message queuing telemetry transport (MQTT) protocol and provides monitoring information through the developed cloud-based webpage. In addition, the online monitoring system provides information on the electrode status, which is determined based on a self-diagnostic index (SDI, with a range of 0-100) of the electrode drift and sensitivity. The diagnostic method for monitoring and reporting the electrode status was validated in a one-month-long laboratory test followed by a field test in a stream near an agricultural facility. Moreover, a self-diagnostic index (SDI) was applied in the final field experiments with an accuracy of 0.77. English MDPI Water Nitrate Remote Monitoring System with Self-Diagnostic Function for Ion-Selective Electrodes Article 10.3390/s21082703 1 SENSORS, v.21, no.8 SENSORS 21 8 N scie scopus 000644819200001 2-s2.0-85103878719 Chemistry, Analytical Engineering, Electrical & Electronic Instruments & Instrumentation Chemistry Engineering Instruments & Instrumentation Article SENSOR ARRAYS VALIDATION DRAINAGE online monitoring ion-selective electrode self-diagnostic method MQTT