Graphene electronic tattoo sensors for point-of-care personal health monitoring and human–machine interfaces

Abstract Electronic tattoo (e-tattoo) sensors are an emerging class of truly wearable ultrathin and ultrasoft sensors. One of the latest advancements in e-tattoo sensors is made by utilizing graphene in fabrication of these sensors. The graphene electronic tattoo (GET) sensors are a group of stretchable soft sensors with the overall thickness of less than 500 nm and optical transparency of more than 85% in visible region. Owing to the ultra-thinness and softness of GET sensors, they conform to the microscopic textures of skin and adhere mainly by van der Waals forces for the extended amount of time without any adhesive. GET sensors are formed in open-mesh structure, which makes them breathable and stiffness-negligible. Despite being dry sensors, ultra-conformable GET sensors exhibit electrode–skin interface impedance that is comparable to medical-grade wet gel (Ag/AgCl) electrodes. The GET fabrication, characterization, and applications for different noninvasive physiological sensing including electroencephalography, electrocardiography, electrooculography, electromyography, skin temperature sensing, skin hydration sensing, and human–machine interface will be discussed in this chapter.