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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 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 - 2018 Jul 6


  • Amine termination
  • Boron-doped diamond
  • Carboxyl termination
  • Electrolyte-solution-gate field-effect-transistor
  • PH sensitivity
  • Polycrystalline diamond

ASJC Scopus subject areas

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


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