ETTORE MASSERA*, VERA LA FERRARA, MARA MIGLIETTA, TIZIANA POLICHETTI, IVANA NASTI, GIROLAMO DI FRANCIA
*Corresponding author
Italian National Agency for New Technologies, Energy and Sustainable Economic Development – ENEA UTTP-MDBp.le E. Fermi 1, Portici (Naples), I-80055, Italy

Abstract

Graphene’s electronic properties are strongly affected by the adsorption of molecules making this material very attractive for gas sensing application. The present work investigates the use of graphene as gas sensing active layer. Herein, two different approaches to fabricate graphene conductometric sensors were persued: a mechanically exfoliated single graphene flake device and a thin film of chemically exfoliated graphene flakes device. First preliminary findings indicated the second approach as a promising and simple method to fabricate a graphene based chemiresistor. Electrical sensor characterizations towards NO₂ and moisture are shown. Issues related to fabrication processes are also discussed.

INTRODUCTION

Graphene is a monolayer of carbon atoms arranged in a two-dimensional honeycomb structure, and is the starting point for any material derived from carbon (fullerenes, nanotubes or graphite). Graphene’s electronic properties are strongly affected by the adsorption of molecules (1), a prerequisite for an optimal electrically based sensor. This sensitivity has two main origins. in one hand, the two-dimensional nature of graphene allows a total exposure of all its atoms to the adsorbing gas molecules, providing the greatest sensor area per unit volume (2). In the other hand, it has inherently low electrical noise due to the quality of its crystal lattice and again, to its two-dimensional nature, which tends to screen charge fluctuations more than one-dimensional systems such as carbon nanotubes. Beyond its desirable electronic properties, graphene has other practical advantages for making sensors, such as its amenability for making devices using conventional lithographic approaches and the good long-term stability of the material (3, 4).
The potential use of graphene for gas sensing is well underlined by the study of Schedin et al (2), ...