Printed Graphene for Energy Storage and Sensing Applications

Nagar Bhawna

Prof. Pedro Gómez-Romero Prof. Arben Merkoçi

We recently celebrated 15 years of graphene since its isolation and characterization in 2004, and it is already on its way to be morphed into a credible and marketable technology! The €1 billion invested alone in Europe for the graphene flagship in 2013 speaks greatly about its credibility and ability for industrial applications. Evidently, graphene has shown its exceptional potential in numerous applications, and therefore it is reasonable to invest resources for finding ways to use it for mass applications, especially in terms of production and processability. This growing need and high potential motivated us to work towards researching ways in which we can efficiently process and pattern graphene focusing on its commercial exploitation. The challenge in the thesis was to fabricate devices that offer not only high performances but are also industrially feasible, eco-friendly as well as cost effective. This challenge to integrate research with simple printing/patterning techniques in order to bring the fabrication procedures at laboratory level closer to real applications was undertaken in this thesis. Graphene electrodes for supercapacitor and sensing applications were prepared during the thesis while keeping in mind their upscaling for possible commercial applications: 1) For supercapacitors, high energy and power density devices (with high capacitances) had been demonstrated over cheap (and environmentally friendly) substrates like carbon cloth, paper (common A4 paper) and plastics using combinations of different printing techniques, graphene hybrids as well as hybrid electrolytes. An innovative and compatible (with substrate and patterning technique) water dispersible graphene ink was prepared for one of the device fabrications using an up-scalable ball-mill technique. Screen printing graphene hybrid ink was also formulated for large scale efficient patterning of interdigitated electrodes etc. 2) For sensing applications, high sensitivity DNA biosensor for viruses using one step easy printing was designed and implemented, the structure and operation of which in principle could be extended to other bio-analytes of interest for applications in various other sensing areas. A ready to use biosensors, without the need of any further modification was demonstrated enabling a user-friendly approach. In another study, highly concentrated yet stable inkjet printable graphene ink was prepared by careful selection on the type and size of graphene and by simply modulating the formulation. This novel graphene ink prepared produced highly conducting patterns that in principle can offer other bio or chemical sensing with high sensitivities as well as electrodes for electrochemical devices. The ink is already of interest for the swiss based company SensAsion to prepare electrodes for bacterial sensing!! These innovative techniques and designs are undoubtedly of interest for their commercial exploitations and could help the ongoing research for its development.

The proposal is worth pursuing as it is highly focused to resolve the many technical issues related with graphene electrode fabrication at industrial level that are of key importance for the advancement in carbon based printed electronics area. A very simple Strategy that merges all individual steps into printing a simple platform and avoiding the need for multiple expensive instruments has been proposed. It is envisioned that the present concept could be scalable from point-of-care assay to automated centralized testing in which a large number of samples could be treated. This can lead to the development of a fast and reliable bacterial infection diagnosis tool by reduction in total diagnosis time thereby aiding quick anti-infective therapy. The proposed method can be applied to all types of culturable bacterial pathogens in various body fluids. It is expected that with the combination of existing techniques along with the creative and innovative ideas, we will be able to achieve good quality, easy and economic solutions to the current techniques and possible breaking of the laboratory-Industry barrier.

Graphene; Isolation; Characterization; Marketable Technology; Graphene Flagship; Industrial Applications; Exceptional Potential; Mass Applications; Production; Processability; Commercial Exploitation; High Performances; Industrially Feasible; Eco-Friendly; Cost Effective; Printing Techniques; Patterning Techniques; Laboratory Level Fabrication; Real Applications; Graphene Electrodes; Supercapacitor Applications; Sensing Applications; Upscaling; Commercial Applications; High Energy Density; High Power Density; High Capacitances; Carbon Cloth; Paper; Plastics; Printing Techniques; Graphene Hybrids; Hybrid Electrolytes; Water Dispersible Graphene Ink; Up-scalable Ball-Mill Technique; Screen Printing Graphene Hybrid Ink; Large Scale Patterning; Interdigitated Electrodes; High Sensitivity DNA Biosensor; Viruses; One Step Easy Printing; Bio-analytes; User-friendly Biosensors; Inkjet Printable Graphene Ink; High Conductivity Patterns; Bio Sensing; Chemical Sensing; Electrochemical Devices; SensAsion; Bacterial Sensing; Innovative Techniques; Designs; Commercial Exploitations; Research Development.