Carboxyl-functionalized graphene SGFET: pH sensing mechanism and reliability of anodization

S. Falina, M. Syamsul, Y. Iyama, M. Hasegawa, Y. Koga, Hiroshi Kawarada

    Research output: Contribution to journalArticle

    Abstract

    In this work, we fabricated graphene solution-gate field-effect transistor (SGFET) to investigate the pH sensitivity of carboxyl functional groups. The functionalization of graphene with carboxyl was achieved through anodization by applying a sequential potential scan from 0.6 V to 1.3 V in 0.1 V steps. Raman spectroscopy was used to determine the defect density of the graphene caused by the anodization. The sequential anodization in Carmody buffer solution at pH 7 had low defective effect on graphene structure and shows that the original structure of graphene was conserved. Furthermore, we measured pH sensitivity of the carboxyl-functionalized graphene at pH 2 to pH 12. The pH sensitivity was 32.6 mV/pH at low pH region and pH sensitivity measurement was saturated at high pH (basic region). The negatively charged surface of carboxyl-functionalized graphene caused weak pH detection in the basic region. The pH sensing mechanism of carboxyl functionalized graphene in the low and high pH region is discussed in detail. The reliability of the carboxyl-functionalized graphene SGFET device was evaluated by measuring pH sensitivity repetitively after anodization at different potential scans of 0.9 V, 1.3 V, 1.5 V, 1.7 V and 1.9 V which demonstrated in all cases that, the pH sensitivity of carboxyl functionalization on graphene SGFET shows a similar trend. This functionalization method allows the modification of the graphene surface for further uses in biosensing.

    Original languageEnglish
    Pages (from-to)15-21
    Number of pages7
    JournalDiamond and Related Materials
    Volume91
    DOIs
    Publication statusPublished - 2019 Jan 1

    Fingerprint

    Gates (transistor)
    Graphite
    Graphene
    Defect density
    Functional groups
    Raman spectroscopy
    Buffers

    Keywords

    • Biocompatibility
    • Defect characterization
    • Oxidation
    • Sensors

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Chemistry(all)
    • Mechanical Engineering
    • Materials Chemistry
    • Electrical and Electronic Engineering

    Cite this

    Carboxyl-functionalized graphene SGFET : pH sensing mechanism and reliability of anodization. / Falina, S.; Syamsul, M.; Iyama, Y.; Hasegawa, M.; Koga, Y.; Kawarada, Hiroshi.

    In: Diamond and Related Materials, Vol. 91, 01.01.2019, p. 15-21.

    Research output: Contribution to journalArticle

    Falina, S. ; Syamsul, M. ; Iyama, Y. ; Hasegawa, M. ; Koga, Y. ; Kawarada, Hiroshi. / Carboxyl-functionalized graphene SGFET : pH sensing mechanism and reliability of anodization. In: Diamond and Related Materials. 2019 ; Vol. 91. pp. 15-21.
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