Flexible textile ion sensors based on reduced graphene oxide/fullerene and their potential applications of sweat characterization

A strategy was proposed to modify cotton fabrics (CFs) by dipping-padding procedure using graphene oxide (GO) and aminofullerene (C60), and then the flexible reduced GO/fullerene fabric-based ion sensors (RGO/C60@CF) were prepared by chemical reduction method. Large amounts of zero-dimension of fullerene spheres were embedded in RGO sheets, and could exhibit different dipole–dipole interactions on various cations or anions with different sizes by virtue of their electron deficiency characteristics, which made RGO/C60@CF show different resistivity to different ions, thus endowing the modified fabrics with responsiveness to different ions. When the relative content of fullerene to graphene was 5%, the resistivity of the modified fabric (RGO/CF60@CF-5) was significantly different to different ions, i.e., the larger the ion radius, the greater the resistivity of the modified fabrics, and even if the ion concentration was only 1 mmol/L, RGO/C60@CF-5 exhibited good sensitivity. In addition, the fabric-based ion sensors also showed different sensing properties for different type of sweat, and their sensitivity only changed slightly after 1000 times of 180° bending. This work provides a basis for the design of the next generation of intelligent ion sensors with high sensitivity and flexibility.