{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,11]],"date-time":"2026-02-11T13:47:35Z","timestamp":1770817655246,"version":"3.50.1"},"reference-count":31,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2018,7,6]],"date-time":"2018-07-06T00:00:00Z","timestamp":1530835200000},"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":["26220903"],"award-info":[{"award-number":["26220903"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this paper, we report on the effect of carboxyl- and amine terminations on a boron-doped diamond surface (BDD) in relation to pH sensitivity. Carboxyl termination was achieved by anodization oxidation in Carmody buffer solution (pH 7). The carboxyl-terminated diamond surface was exposed to nitrogen radicals to generate an amine-terminated surface. The pH sensitivity of the carboxyl- and amine-terminated surfaces was measured from pH 2 to pH 12. The pH sensitivities of the carboxyl-terminated surface at low and high pH are 45 and 3 mV\/pH, respectively. The pH sensitivity after amine termination is significantly higher\u2014the pH sensitivities at low and high pH are 65 and 24 mV\/pH, respectively. We find that the negatively-charged surface properties of the carboxyl-terminated surface due to ionization of \u2013COOH causes very low pH detection in the high pH region (pH 7\u201312). In the case of the amine-terminated surface, the surface properties are interchangeable in both acidic and basic solutions; therefore, we observed pH detection at both low and high pH regions. The results presented here may provide molecular-level understanding of surface properties with charged ions in pH solutions. The understanding of these surface terminations on BDD substrate may be useful to design diamond-based biosensors.<\/jats:p>","DOI":"10.3390\/s18072178","type":"journal-article","created":{"date-parts":[[2018,7,6]],"date-time":"2018-07-06T10:55:44Z","timestamp":1530874544000},"page":"2178","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":16,"title":["Role of Carboxyl and Amine Termination on a Boron-Doped Diamond Solution Gate Field Effect Transistor (SGFET) for pH Sensing"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0875-9903","authenticated-orcid":false,"given":"Shaili","family":"Falina","sequence":"first","affiliation":[{"name":"Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan"}]},{"given":"Sora","family":"Kawai","sequence":"additional","affiliation":[{"name":"Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan"}]},{"given":"Nobutaka","family":"Oi","sequence":"additional","affiliation":[{"name":"Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan"}]},{"given":"Hayate","family":"Yamano","sequence":"additional","affiliation":[{"name":"Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan"}]},{"given":"Taisuke","family":"Kageura","sequence":"additional","affiliation":[{"name":"Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan"}]},{"given":"Evi","family":"Suaebah","sequence":"additional","affiliation":[{"name":"Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0682-3011","authenticated-orcid":false,"given":"Masafumi","family":"Inaba","sequence":"additional","affiliation":[{"name":"Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan"},{"name":"Institute of Materials and Systems for Sustainability, Nagoya University, Furo-Cho, Chikusa-ku, Nagoya 464-8603, Japan"}]},{"given":"Yukihiro","family":"Shintani","sequence":"additional","affiliation":[{"name":"Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan"},{"name":"Research and Development Department\/Innovation Center, MK-Headquarters, Yokogawa Electric Corporation, Tokyo 180-8750, Japan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3236-3303","authenticated-orcid":false,"given":"Mohd","family":"Syamsul","sequence":"additional","affiliation":[{"name":"Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan"}]},{"given":"Hiroshi","family":"Kawarada","sequence":"additional","affiliation":[{"name":"Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan"},{"name":"The Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, 2-8-26 Nishiwaseda, Shinjuku, Tokyo 169-0051, Japan"}]}],"member":"1968","published-online":{"date-parts":[[2018,7,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"746","DOI":"10.1007\/s10008-006-0120-4","article-title":"pH Monitoring: A review","volume":"10","author":"Vonau","year":"2006","journal-title":"J. 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