Developing Electrically and Thermally Conductive Hydrogel Based on Graphene Suitable for Bio-Thermistor

This thesis focuses on the development of a family of flexible conductive hydrogels based on graphene and Poly (3, 4-ethylenedioxy thiophen):poly (styrenesulfonate) (PEDOT:PSS) as fillers of a polyurethane (PU) matrix. This thesis describes the novel modification of Liquid Crystal Graphene Oxide (LCGO) with chloride salts with an increase of the storage moduli, viscosity and thermal conductivity. Development of novel processable conductive hydrogel (PUHC) via blending LCGO and PEDOT:PSS within PU matrix is described, along with the processability and biocompatibility assessment. The PUHC was used in the fabrication of a temperature sensor, with the processability and performance of the developed PUHC temperature sensor (Ts-PUHC) discussed. Study on the electrical and mechanical performance of PUHC was continued with an investigation of the thermal properties, thermal expansion, and the impact of prestrain on the PUHC properties. Finally, rheological behaviour and preparation of 3D printable PUHC ink is investigated and discussed. To the best of my knowledge, this is the first reported printable composite without any post-treatment that can offer negative temperature coefficient of resistance (NTC) behaviour under ambient conditions with adjustable thermal and electrical conductivity, and stretchability within the temperature range of the human body (25 - 45C). The thesis concludes with suggestions for further work that include both theoretical and practical areas.