Open Access Nano Idea

Analytical modelling of monolayer graphene-based ion-sensitive FET to pH changes

Mohammad Javad Kiani12, Mohammad Taghi Ahmadi1*, Hediyeh Karimi Feiz Abadi34, Meisam Rahmani1, Amin Hashim1 and Fauzan Khairi Che harun1

Author Affiliations

1 Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Skudai, Johor Bahru 81310, Malaysia

2 Department of Electrical Engineering, Islamic Azad University, Yasooj Branch, Yasooj 7591483587, Iran

3 Malaysia-Japan International Institute of Technology (MJIIT), Universiti Teknologi Malaysia, Johor Bahru 54100, Malaysia

4 Centre for Artificial Intelligence and Robotics (CAIRO), Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Johor Bahru 81310, Malaysia

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Nanoscale Research Letters 2013, 8:173  doi:10.1186/1556-276X-8-173

Published: 16 April 2013

Abstract

Graphene has attracted great interest because of unique properties such as high sensitivity, high mobility, and biocompatibility. It is also known as a superior candidate for pH sensing. Graphene-based ion-sensitive field-effect transistor (ISFET) is currently getting much attention as a novel material with organic nature and ionic liquid gate that is intrinsically sensitive to pH changes. pH is an important factor in enzyme stabilities which can affect the enzymatic reaction and broaden the number of enzyme applications. More accurate and consistent results of enzymes must be optimized to realize their full potential as catalysts accordingly. In this paper, a monolayer graphene-based ISFET pH sensor is studied by simulating its electrical measurement of buffer solutions for different pH values. Electrical detection model of each pH value is suggested by conductance modelling of monolayer graphene. Hydrogen ion (H+) concentration as a function of carrier concentration is proposed, and the control parameter (Ƥ) is defined based on the electro-active ions absorbed by the surface of the graphene with different pH values. Finally, the proposed new analytical model is compared with experimental data and shows good overall agreement.

Keywords:
Graphene; Ion-sensitive field-effect transistor (ISFET); pH sensor; Conductance