An All-Solid-State pH Sensor Employing Fluorine-Terminated Polycrystalline Boron-Doped Diamond as a pH-Insensitive Solution-Gate Field-Effect Transistor

Yukihiro Shintani; Mikinori Kobayashi; Hiroshi Kawarada

doi:10.3390/s17051040

An All-Solid-State pH Sensor Employing Fluorine-Terminated Polycrystalline Boron-Doped Diamond as a pH-Insensitive Solution-Gate Field-Effect Transistor

Sensors (Basel). 2017 May 5;17(5):1040. doi: 10.3390/s17051040.

Authors

Yukihiro Shintani^{1

2}, Mikinori Kobayashi³, Hiroshi Kawarada^{4

5}

Affiliations

¹ Graduate School of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan. shintani@toki.waseda.jp.
² R&D Departent, Innovation Center, MK-Hdqrs, Yokogawa Electric Corporation, Japan, 2-9-32 Nakacho, Musashino, Tokyo 180-8750, Japan. shintani@toki.waseda.jp.
³ Graduate School of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan. epsilon_koba@asagi.waseda.jp.
⁴ Graduate School of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan. kawarada@waseda.jp.
⁵ The Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, 2-8-26 Nishiwaseda, Shinjuku, Tokyo 169-0051, Japan. kawarada@waseda.jp.

Abstract

A fluorine-terminated polycrystalline boron-doped diamond surface is successfully employed as a pH-insensitive SGFET (solution-gate field-effect transistor) for an all-solid-state pH sensor. The fluorinated polycrystalline boron-doped diamond (BDD) channel possesses a pH-insensitivity of less than 3mV/pH compared with a pH-sensitive oxygenated channel. With differential FET (field-effect transistor) sensing, a sensitivity of 27 mv/pH was obtained in the pH range of 2-10; therefore, it demonstrated excellent performance for an all-solid-state pH sensor with a pH-sensitive oxygen-terminated polycrystalline BDD SGFET and a platinum quasi-reference electrode, respectively.

Keywords: all-solid-state pH sensor; electrolyte-solution-gate field-effect transistor; fluorine-termination; pH-insensitivity; polycrystalline boron-doped diamond.