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.

LanguageEnglish
Pages15-21
Number of pages7
JournalDiamond and Related Materials
Volume91
DOIs
Publication statusPublished - 2019 Jan 1

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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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