Resumen de Printed graphene for energy storage and sensing applications
The focus of this thesis has been the design and preparation of flexible graphene-based electrodes and their printing using different techniques for applications in energy storage, specifically supercapacitors and electrochemical sensing devices. Different strategies have been employed keeping in mind the end application and accordingly graphene or its hybrids were prepared using different synthetic routes along with careful selection of the available printing techniques as well as the substrates. For energy storage part (Chapter 2), Supercapacitor devices with high capacitances, energy and power density have been demonstrated over Cloth (Carbon), Paper (Common A4 paper) and Plastic substrates using different printing techniques, graphene hybrids as well as hybrid electrolytes. In the case of Sensing applications (Chapter 3), two sensors have been demonstrated over plastic substrates. A high sensitivity DNA (Bio)sensor for viruses using one step facile printing is shown, the structure and operation of which in principle can be extended to other bio-analytes with interest for applications in various areas. In another study, extremely high concentration yet stable graphene inkjet printable ink has been prepared and its use as a bacterial sensor has been demonstrated as a proof of concept. The graphene ink prepared could produce highly conducting patterns that in principle can offer other bio or chemical sensing with high sensitivities.
Studies of different printing techniques were carried out and suitable inks were formulated and tested for each technique with optimization of the printing parameters in order to obtain reproducible films and hence reproducible device fabrication has been the focus. The main printing/coating techniques used in this Thesis are Doctor blade coating, Inkjet printing, screen printing and wax stamping technique. The project therefore involved a very important part of synthesis and characterization of graphene and derivatives, formulation of inks and finally device integration and testing.
