{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,20]],"date-time":"2026-02-20T18:55:20Z","timestamp":1771613720107,"version":"3.50.1"},"reference-count":32,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2021,4,12]],"date-time":"2021-04-12T00:00:00Z","timestamp":1618185600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"This research was supported by the Rural Development Administration","award":["(Project number: PJ0149112021)"],"award-info":[{"award-number":["(Project number: PJ0149112021)"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>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\u2013100) 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.<\/jats:p>","DOI":"10.3390\/s21082703","type":"journal-article","created":{"date-parts":[[2021,4,12]],"date-time":"2021-04-12T11:05:06Z","timestamp":1618225506000},"page":"2703","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Water Nitrate Remote Monitoring System with Self-Diagnostic Function for Ion-Selective Electrodes"],"prefix":"10.3390","volume":"21","author":[{"given":"Dae-Hyun","family":"Jung","sequence":"first","affiliation":[{"name":"Department of Biosystems and Biomaterial Engineering, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea"},{"name":"Smart Farm Research Center, Korea Institute of Science and Technology (KIST), Gangneung-si 25451, Korea"}]},{"given":"Hak-Jin","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Biosystems and Biomaterial Engineering, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea"},{"name":"Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea"},{"name":"BK21 Global Smart Farm Educational Research Center, Seoul National University, Seoul 08826, Korea"}]},{"given":"Joon Yong","family":"Kim","sequence":"additional","affiliation":[{"name":"Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5846-4233","authenticated-orcid":false,"given":"Soo Hyun","family":"Park","sequence":"additional","affiliation":[{"name":"Smart Farm Research Center, Korea Institute of Science and Technology (KIST), Gangneung-si 25451, Korea"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5216-5603","authenticated-orcid":false,"given":"Woo Jae","family":"Cho","sequence":"additional","affiliation":[{"name":"Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea"},{"name":"Division of Agro-System Engineering, College of Agriculture and Life Science, Gyeongsang National University, Jinju 52828, Korea"}]}],"member":"1968","published-online":{"date-parts":[[2021,4,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"743","DOI":"10.2134\/jeq1996.00472425002500040014x","article-title":"Nitrate removal in stream riparian zones","volume":"25","author":"Hill","year":"1996","journal-title":"J. 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