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.
Highlights
Graphene has two sp2-bonded carbon atoms, which make its structure apparently look like a honeycomb crystal as seen in Figure 1 [1,2,3]
The focus of this paper is to present a new model for ion-sensitive field-effect transistor (ISFET) to measure pH changes; in other words, the conductance of the ISFET device as a function of different pH values is simulated and the pH factor (Ƥ) is suggested
The emerging potentials of nanostructured graphene-based ISFETs with high sensitivity and ability to readily detect have been applied to electrochemical catalysis through pH sensing
Summary
Graphene has two sp2-bonded carbon atoms, which make its structure apparently look like a honeycomb crystal as seen in Figure 1 [1,2,3]. The reaction between solution with different pH values and the surface of graphene has a notable effect on the conductivity of graphene [36] The focus of this paper is to present a new model for ISFET to measure pH changes; in other words, the Figure 6 Comparison between graphene conductance model and extracted experimental data [42] for different pH values. It is notable that the temperature remains constant (about 25°C in solution) in the suggested model as the temperature can have an effect on the behavior of the sensing parameter as well
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