{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T16:00:00Z","timestamp":1791302400985,"version":"4.1.0"},"reference-count":22,"publisher":"American Chemical Society (ACS)","issue":"39","license":[{"start":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T00:00:00Z","timestamp":1789948800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["24K02819"],"award-info":[{"award-number":["24K02819"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,10,6]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Wearable ion sensors have gained increasing attention for the continuous noninvasive monitoring of ions in body fluids such as sweat. However, printed reference electrodes commonly used in potentiometric ion sensors require prolonged conditioning to achieve stable potentials, which limits practical wearable applications. Here, we integrated a screen-printed liquid-junction reference-electrode architecture with dual Na+- and K+-selective electrodes in a wearable wristwatch-type sensing platform. The liquid-junction reference becomes operable without the prolonged preconditioning required by poly(vinyl butyral) (PVB)-type printed references. The sensor exhibited sensitivities of 48.3 mV decade\u20131 for Na+ and 46.4 mV decade\u20131 for K+. The printed reference electrode drifted by approximately 6 mV over 3000 s against a commercial reference in 10 mM NaCl. A control reference electrode fabricated without the liquid-junction layer showed a substantially greater dependence on the external KCl concentration, supporting the functional role of the liquid-junction layer. A fabric layer and a superabsorbent-fiber (SAF) layer were incorporated as a physical barrier and a sample-handling structure. A wristwatch-type wireless device was designed and constructed for real-time data acquisition, wireless transmission, and local storage on an SD card. The complete system was deployed at an active construction site. During on-body testing with a volunteer construction worker, the system acquired Na+- and K+-responsive potentiometric signals in real time, which were converted to apparent ion concentrations using aqueous calibration curves, over a working period of approximately 2 h 45 min<\/jats:p>","DOI":"10.1021\/acsomega.6c04240","type":"journal-article","created":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T14:03:19Z","timestamp":1789999399000},"page":"59011-59020","source":"Crossref","is-referenced-by-count":0,"title":["Real-Time Monitoring\nwith a Wristwatch-Type Sodium-\nand Potassium-Ion Sensor Using a Screen-Printed Liquid-Junction Reference\nElectrode"],"prefix":"10.1021","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9751-016X","authenticated-orcid":true,"given":"Isao","family":"Shitanda","sequence":"first","affiliation":[{"name":"Tokyo University of Science , , 2641 Yamazaki , , ,","place":["Noda, Chiba, Japan, 278-8510"]},{"name":"Tokyo University of Science , , 2641 Yamazaki , , ,","place":["Noda, Chiba, Japan, 278-8510"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-5703-1726","authenticated-orcid":true,"given":"Takuma","family":"Fujisawa","sequence":"additional","affiliation":[{"name":"Tokyo University of Science , , 2641 Yamazaki , , ,","place":["Noda, Chiba, Japan, 278-8510"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Noya","family":"Loew","sequence":"additional","affiliation":[{"name":"Tokyo University of Science , , 2641 Yamazaki , , ,","place":["Noda, Chiba, Japan, 278-8510"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7034-1690","authenticated-orcid":true,"given":"Ryo","family":"Shirai","sequence":"additional","affiliation":[{"name":"Kyoto University , , 36 Yoshida-honmachi , , ,","place":["Sakyo-ku, Kyoto, Japan, 606-8501"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-3884-0121","authenticated-orcid":true,"given":"Yuta","family":"Imade","sequence":"additional","affiliation":[{"name":"Tokyo University of Science , , 2641 Yamazaki , , ,","place":["Noda, Chiba, Japan, 278-8510"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuri","family":"Okamoto","sequence":"additional","affiliation":[{"name":"Tokyo University of Science , , 2641 Yamazaki , , ,","place":["Noda, Chiba, Japan, 278-8510"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-5466-1173","authenticated-orcid":true,"given":"Shinya","family":"Yanagita","sequence":"additional","affiliation":[{"name":"Tokyo University of Science , , 2641 Yamazaki , , ,","place":["Noda, Chiba, Japan, 278-8510"]},{"name":"Tokyo University of Science , , 2641 Yamazaki , , ,","place":["Noda, Chiba, Japan, 278-8510"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1547-7042","authenticated-orcid":true,"given":"Hikari","family":"Watanabe","sequence":"additional","affiliation":[{"name":"Tokyo University of Science , , 2641 Yamazaki , , ,","place":["Noda, Chiba, Japan, 278-8510"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3422-3344","authenticated-orcid":true,"given":"Masayuki","family":"Itagaki","sequence":"additional","affiliation":[{"name":"Tokyo University of Science , , 2641 Yamazaki , , ,","place":["Noda, Chiba, Japan, 278-8510"]},{"name":"Tokyo University of Science , , 2641 Yamazaki , , ,","place":["Noda, Chiba, Japan, 278-8510"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,9,21]]},"reference":[{"key":"2026100610504211700_cit1","doi-asserted-by":"publisher","first-page":"389","DOI":"10.1038\/s41587-019-0045-y","article-title":"Wearable Biosensors\nfor Healthcare Monitoring","volume":"37","author":"Kim","year":"2019","journal-title":"Nat. Biotechnol."},{"key":"2026100610504211700_cit2","doi-asserted-by":"publisher","first-page":"217","DOI":"10.1039\/C7LC00914C","article-title":"Wearable Sensors:\nModalities, Challenges, and Prospects","volume":"18","author":"Heikenfeld","year":"2018","journal-title":"Lab Chip"},{"key":"2026100610504211700_cit3","doi-asserted-by":"publisher","first-page":"464","DOI":"10.1021\/acssensors.6b00250","article-title":"Wearable Chemical Sensors: Present\nChallenges and Future Prospects","volume":"1","author":"Bandodkar","year":"2016","journal-title":"ACS Sens."},{"key":"2026100610504211700_cit4","doi-asserted-by":"publisher","first-page":"407","DOI":"10.1038\/s41587-019-0040-3","article-title":"Accessing\nAnalytes in Biofluids for\nPeripheral Biochemical Monitoring","volume":"37","author":"Heikenfeld","year":"2019","journal-title":"Nat. Biotechnol."},{"key":"2026100610504211700_cit5","doi-asserted-by":"publisher","first-page":"129447","DOI":"10.1016\/j.snb.2021.129447","article-title":"Recent\nProgress, Challenges, and\nOpportunities for Wearable Biochemical Sensors for Sweat Analysis","volume":"332","author":"Ghaffari","year":"2021","journal-title":"Sens. Actuators, B"},{"key":"2026100610504211700_cit6","doi-asserted-by":"publisher","first-page":"136769","DOI":"10.1016\/j.snb.2024.136769","article-title":"Biological Ce\/Fe-Metal\nOrganic Framework Multifunctional Nanozyme-Based Colorimetric Sensor\nArray for Multi-Analyte Detection in Human Sweat","volume":"423","author":"Beygnezhad","year":"2025","journal-title":"Sens. Actuators, B"},{"key":"2026100610504211700_cit7","doi-asserted-by":"publisher","first-page":"580","DOI":"10.1007\/s00604-024-06564-1","article-title":"Wearable Electrochemical\nDevice Based on Butterfly-Like Paper-Based Microfluidics for pH and\nNa+ Monitoring in Sweat","volume":"191","author":"Fiore","year":"2024","journal-title":"Microchim. Acta"},{"key":"2026100610504211700_cit8","doi-asserted-by":"publisher","first-page":"126986","DOI":"10.1016\/j.talanta.2024.126986","article-title":"Flexible Epidermal\nWearable Sensor for Athlete\u2019s Sweat Biomarkers Monitoring","volume":"282","author":"Cai","year":"2025","journal-title":"Talanta"},{"key":"2026100610504211700_cit9","doi-asserted-by":"publisher","first-page":"2335","DOI":"10.1021\/acsnano.3c10324","article-title":"Stretchable and Smart\nWettable Sensing Patch with Guided Liquid Flow\nfor Multiplexed in Situ Perspiration Analysis","volume":"18","author":"Sun","year":"2024","journal-title":"ACS Nano"},{"key":"2026100610504211700_cit10","doi-asserted-by":"publisher","first-page":"117844","DOI":"10.1016\/j.bios.2025.117844","article-title":"An Artificial\nIntelligence-Assisted, Kilometer-Scale Wireless and Wearable Biochemical\nSensing Platform for Monitoring of Key Biomarkers in Urine","volume":"288","author":"Dong","year":"2025","journal-title":"Biosens. Bioelectron."},{"key":"2026100610504211700_cit11","doi-asserted-by":"publisher","first-page":"145834","DOI":"10.1016\/j.electacta.2025.145834","article-title":"A Point-of-Care, Label-Free\nOECT Sensor for Uric Acid Detection: Validation in Human Saliva","volume":"519","author":"Ceccardi","year":"2025","journal-title":"Electrochim. Acta"},{"key":"2026100610504211700_cit12","doi-asserted-by":"publisher","first-page":"14948","DOI":"10.1038\/s41598-025-99624-2","article-title":"Plasmonic Smart\nContact Lens Based on Etalon Nanostructure\nfor Tear Glucose Sensing","volume":"15","author":"Roostaei","year":"2025","journal-title":"Sci. Rep."},{"key":"2026100610504211700_cit13","doi-asserted-by":"publisher","first-page":"509","DOI":"10.1038\/nature16521","article-title":"Fully Integrated Wearable Sensor Arrays for Multiplexed in Situ Perspiration\nAnalysis","volume":"529","author":"Gao","year":"2016","journal-title":"Nature"},{"key":"2026100610504211700_cit14","doi-asserted-by":"publisher","first-page":"1497","DOI":"10.3390\/mi14081497","article-title":"Screen-Printed Wearable Sweat Sensor for Cost-Effective Assessment\nof Human Hydration Status through Potassium and Sodium Ion Detection","volume":"14","author":"Yang","year":"2023","journal-title":"Micromachines"},{"key":"2026100610504211700_cit15","doi-asserted-by":"publisher","first-page":"2889","DOI":"10.1021\/acssensors.3c01027","article-title":"Wearable Ion\nSensors for the Detection\nof Sweat Ions Fabricated by Heat-Transfer Printing","volume":"8","author":"Shitanda","year":"2023","journal-title":"ACS Sens."},{"key":"2026100610504211700_cit16","doi-asserted-by":"publisher","first-page":"1253","DOI":"10.1002\/elan.201200059","article-title":"All-Solid-State\nIon Selective and All-Solid-State Reference Electrodes","volume":"24","author":"Michalska","year":"2012","journal-title":"Electroanalysis"},{"key":"2026100610504211700_cit17","doi-asserted-by":"publisher","first-page":"72","DOI":"10.1016\/j.aca.2014.02.028","article-title":"A Reference Electrode\nBased on Polyvinyl Butyral (PVB) Polymer for Decentralized Chemical\nMeasurements","volume":"821","author":"Guinovart","year":"2014","journal-title":"Anal. Chim. Acta"},{"key":"2026100610504211700_cit18","doi-asserted-by":"publisher","first-page":"343713","DOI":"10.1016\/j.aca.2025.343713","article-title":"A Novel\nType of Planar Reference Electrodes Based on Ionic Liquids","volume":"1344","author":"Kuczak","year":"2025","journal-title":"Anal. Chim. Acta"},{"key":"2026100610504211700_cit19","doi-asserted-by":"publisher","first-page":"2593","DOI":"10.1134\/S0036024425601375","article-title":"Design, Fabrication,\nand Characterization of a Layered Si\/Ag\/AgCl\/KCl Planar Solid-State\nReference Electrode","volume":"99","author":"Malek","year":"2025","journal-title":"Russ. J. Phys. Chem."},{"key":"2026100610504211700_cit20","doi-asserted-by":"publisher","first-page":"65","DOI":"10.5796\/electrochemistry.18-00075","article-title":"Fabrication and Characterization\nof a Fully Screen-Printed Ag\/AgCl Reference Electrode Using Silica\nGel Inks Exhibiting Instantaneous Usability and Long-Term Stability","volume":"87","author":"Komoda","year":"2019","journal-title":"Electrochemistry"},{"key":"2026100610504211700_cit21","doi-asserted-by":"publisher","first-page":"37","DOI":"10.1111\/j.1365-201X.2004.01305.x","article-title":"Acute Effects of Dehydration on Sweat\nComposition in Men during Prolonged Exercise in the Heat","volume":"182","author":"Morgan","year":"2004","journal-title":"Acta Physiol. Scand."},{"key":"2026100610504211700_cit22","doi-asserted-by":"publisher","first-page":"111","DOI":"10.1007\/s40279-017-0691-5","article-title":"Sweating\nRate and Sweat Sodium Concentration in Athletes: A Review of Methodology\nand Intra\/Interindividual Variability","volume":"47","author":"Baker","year":"2017","journal-title":"Sports\nMed."}],"container-title":["ACS Omega"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/acsomega.6c04240","content-type":"application\/pdf","content-version":"vor","intended-application":"unspecified"},{"URL":"https:\/\/pubs.acs.org\/acsodf\/article-pdf\/11\/39\/59011\/68582310\/acsomega.6c04240.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.acs.org\/acsodf\/article-pdf\/11\/39\/59011\/68582310\/acsomega.6c04240.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T15:30:13Z","timestamp":1791300613000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.acs.org\/acsodf\/article\/11\/39\/59011\/5434357\/Real-Time-Monitoring-with-a-Wristwatch-Type-Sodium"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,21]]},"references-count":22,"journal-issue":{"issue":"39","published-online":{"date-parts":[[2026,9,21]]},"published-print":{"date-parts":[[2026,10,6]]}},"URL":"https:\/\/doi.org\/10.1021\/acsomega.6c04240","relation":{},"ISSN":["2470-1343"],"issn-type":[{"value":"2470-1343","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,21]]}}}