Interfacial phenomena in graphene materials, devices and applications

Abstract

Due to its unique mechanical, optical and electrochemical properties, graphene_x000D_ has raised great interest for biosensing and bioelectronic applications. Although_x000D_ current graphene-based technology has demonstrated remarkable potential in_x000D_ the biomedical field, fundamental knowledge about graphene interaction with_x000D_ the media surrounding it is still missed. This PhD thesis is devoted to the study_x000D_ of interfacial phenomena that can govern the performance of graphene devices,_x000D_ from its synthesis to the final application._x000D_ _x000D_ Concerning graphene synthesis, we prepare rigid, flat and reusable copper_x000D_ supports for the growth of high-quality, large-scale graphene to be used in_x000D_ electronic devices. The engineered Cu-based substrates are presented as a_x000D_ promising alternative to the currently most used Cu foils for graphene growth._x000D_ _x000D_ Graphene based electronic devices in biomedical applications are aimed to work_x000D_ in an aqueous media. In this dissertation, we study how the graphene/substrate_x000D_ and the graphene/electrolyte interfaces govern the electronic performance of_x000D_ such devices. Furthermore, a study of the impact of the wafer-scale fabrication_x000D_ is conducted, highlighting the importance to preserve the graphene surface_x000D_ throughout the process for optimal and reproducible performance of graphene_x000D_ SGFETs._x000D_ _x000D_ For biosensing applications, graphene functionalization is key. In this work,_x000D_ we propose a novel approach based on the in-vacuum sublimation of a pyrene-_x000D_ based molecule. This molecule can be deposited on the graphene surface in_x000D_ a controllable, reproducible way. A methodology for the characterization of_x000D_ the resulting functionalized graphene surface, as well as for the quantification_x000D_ of the functionalization is discussed. The functionality of the functionalized_x000D_ graphene SGFETs is tested in different pH conditions and compared with_x000D_ standard, non-functionalized devices. With that, we demonstrate that the_x000D_ proposed functionalization approach is a promising path towards the optimization_x000D_ of graphene-based biosensors for the detection of a variety of biomolecules,_x000D_ including neurotransmitters.

Date of Award	18 Jul 2024
Original language	English
Supervisor	Elena del Corro Garcia (Director) & José Antonio Garrido Ariza (Director)