Improvement of the Sensitivity and Selectivity of Gas Molecules of Graphene-base Gas Sensor by Applying Carbon Nanotubes

Abstract

Chemical biosensors using graphene as a sensing element have been developed for a new generation of highly-sensitive miniature exhaled multi-gas sensors for early detection of various diseases. In this study, carbon nanotubes (CNTs) were synthesized directly on graphene to increase the surface area of the molecular adsorption in order to improve the sensitivity and selectivity of the graphene-based gas sensor. The synthesis of graphene was performed in a low-pressure chemical vapor deposition apparatus on a very pure copper catalyst substrate. The grown graphene was transferred onto a Si/SiO2 substrate. A CNT layer was also formed directly on the graphene sensor element using a thermochemical vapor deposition method. Stable ohmic contact was observed between the synthesized CNTs and the base graphene layer. It was also confirmed that the sensitivity of the graphene sensor with the CNT layer to gas molecules was improved by about 4 times compared with the conventional graphene sensor.