Fabrication of suspended Graphene microchannels and its application in studying graphene liquid interface

Abstract

Graphene is a single layer of sp2 hybridized carbon atoms having extraordinary mechanical, optical, and electrical properties. These exotic properties make them attractive for applications in all fields of science and technology ranging from flexible electronics to multifunctional biomedical devices. Most of these applications require residue-free, and large-area graphene. Commonly, graphene is grown on copper using a self-limiting chemical vapor deposition process and then transferred to the required substrate. But there are still several fabrication challenges in realizing graphene-based devices. Both process steps cause corrugations and stress related defects in the transferred graphene. Further, graphene obtained on substrates suffer from many drawbacks like deteriorated electron mobility. Thus, platforms with suspended graphene has been pursued for its immense potential. Graphene based devices has been primarily for applications in optical and electronic domains. Graphene based mechanical resonators have been demonstrated for several sensing applications. However, use of graphene in microfluidic applications has been limited. The use of graphene and its derivatives (graphene oxide) based layers have also been limited to biochemical sensing where these layers have been used as functionalised electrode surfaces. Flow of fluids with dissolved ions over graphene has been proposed as a technique for harvesting energy. However, there seems to be a lack of agreement between different experiments. This is primarily due to two reasons. Firstly, most studies have been performed on graphene transferred on various surfaces. Variability in underlying surface across studies effects the overall behaviour. Devices with graphene suspended over microfluidic channels have not been achieved yet due to fabrication challenges. Secondly, due to absence of these devices, studies pertaining to fundamental interaction of liquid with free graphene surface has been missing...