Graphene Synthesis on Electrodeposited Substrates and Its Integration in MEMS for Sensor Applications

Graphene has become a promising material for many different applications, such as nanoelectronic devices, physical, chemical and biochemical sensors, transparent conductive films, clean energy scavenging and storage devices, and nanocomposite formulations. This great variety of possibilities is determined by the exceptional charge transport, optical, and mechanical properties of the material. Recently gas sensing, as a critical application in intelligent systems, is receiving increasing attention between the possible applications in both industry and academy. Sensing applications using graphene sheets as transducers have experienced a surge of activities in recent years, especially for gas sensing platforms and electrochemical sensing, because of the high electrical conductivity and high surface area of graphene. The most intriguing feature of graphene based sensors is that a proper functionalization of graphene enables enhanced selectivity and improved performances. Moreover, by combining graphene electronic and mechanical properties monolithic sensors with superior sensitivity can be developed. Despite the significant amount of work on graphene electronic devices such as the field effect transistor, its use in sensors, actuators or micro and nano-electromechanical systems (MEMS/NEMS) in general is relatively less explored. In this work the synthesis of graphene by precursor decomposition at different temperatures onto free standing electrodeposited substrates is investigated, allowing therefore to study the effects of electrochemically produced substrates onto graphene quality. The production of porous structure obtained dealloying the electrodeposited NiCu substrates will be discussed for the synthesis of porous graphene layers. The specific area of the structure obtained is therefore greatly enhanced, improving in this way the sensing capacity. The growth of good quality graphene layers is also discussed in terms of the role played by grain boundaries and diffusion at the grain boundaries. Finally, graphene coated substrates as electrodes for electrochemical sensor and the integration of graphene layers into MEMS for microsensor production will be presented.