Role of carboxyl and amine termination on a boron-doped diamond solution gate field effect transistor (SGFET) for PH sensing

Shaili Falina, Sora Kawai, Nobutaka Oi, Hayate Yamano, Taisuke Kageura, Evi Suaebah, Masafumi Inaba, Yukihiro Shintani, Mohd Syamsul, Hiroshi Kawarada

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


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—the 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 –COOH causes very low pH detection in the high pH region (pH 7–12). 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.

Original languageEnglish
Article number2178
JournalSensors (Switzerland)
Issue number7
Publication statusPublished - Jul 6 2018
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Biochemistry
  • Atomic and Molecular Physics, and Optics
  • Instrumentation
  • Electrical and Electronic Engineering


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