Designing and manufacturing superamphiphobic flexible sensors

Rapidly developing technology necessitates materials with different functional properties instead of single-functional materials used in traditional production. There are many methods to improve biocompatibility, antibacterial, antistatic, conductive properties and functions in textile materials, fibers and polymers. With the development of multifunctional textile materials, new application areas have emerged. Smart textiles are used in various fields such as medical, defense, industrial and environmental. Smart textiles are also used in the development of sensors and wearable electronics. Recent advances in technology have necessitated the development of flexible and stretchable sensors, and there is a great deal of research completed and ongoing on increasing the flexibility of sensors without losing their sensitivity. Flexible materials provide a wide variety of applications for wearable sensors. Their ability to conform to non-linear surfaces, their elasticity, durability under stress and strain forces, and bending resistance are some of the reasons why flexible materials are preferred as sensor substrates. Flexible substrates for wearable flexible sensors must be compatible with applications on human skin. In this thesis, it is foreseen to design flexible sensors with water and oil repellent properties on textile and polymer surfaces. It is aimed to increase the resistance of the sensors against external factors such as rain, oil leakage and corrosion by giving them a superamphiphobic feature, thus providing durability and long life span without reducing the sensitivity. In this study, researches were conducted on the design and production of flexible sensors on different surfaces and the water and oil repellent properties of the produced sensors. For optimal flexibility, cotton and TPU-based substrate materials were used, carbon-based (graphite, graphene, cathode waste material) and polymer-based (PEDOT:PSS) conductive inks were prepared in different concentrations, inks were applied to the substrate surfaces with doctor blade and spray coating methods, The results were analyzed by coating the electrode with water and oil repellent dispersions. The produced electrodes were characterized in terms of their morphological and electrical properties. Cotton and TPU-based substrate materials were used for optimal flexibility, carbon-based (graphite, graphene, cathode waste material) and polymer-based (PEDOT:PSS) conductive inks were prepared in different concentrations. Inks were applied to the substrate surfaces as 1, 2 and 3 layers of coating by using doctor blade and spray coating methods, the obtained electrode was coated with water and oil repellent fluorocarbon and zinc stearate, silicon dioxide dispersions and the results were analyzed. The produced electrodes were characterized in terms of their morphological and electrical properties. The results showed that graphene had the best conductivity among the inks applied and the results improved as the concentration of carbon-based materials in the ink dispersion and the number of applied layers increased. Tubiguard, a fluorocarbon dispersion used in textile applications hydrophobic and oleophobic coatings was mixed with ZnSt and SiO2 and the results showed that hydrophobic properties were greatly improved and oleophobic properties also showed some improvement. Cotton substrate, a hydrophilic material in its pure form, showed better amphiphobic characteristics after the coatings were applied compared to TPU substrate. The staple fibers of cotton fabric acted as microhiearchical structures with the application of coatings which helped improve their amphiphobic properties. Overall the materials used and methods applied in this study are aimed to keep the costs at an optimal level and allow mass production of electrodes for commercial applications and the results show that the goal is achievable.