Carbon-based sensors

We benefit from various sensors in our daily life with or without being aware of them, and carbon materials are often used as the sensing materials. Here, carbon-based sensors, including their sensing possibilities, are reviewed by classifying the materials into fibrous (carbon nanotubes and nanofibers), graphene-related (graphene, reduced graphene oxide, graphene oxide) and porous (conventional activated carbons and carbon black). The sensors are also classified into chemical sensors, mechanical sensors and biosensors on the bases of their abilities to detect chemicals (inorganic gases, organic vapors), mechanical signals (stress, strain, pressure and temperature), and biological chemicals (such as glucose, protein, DNA, including solution pH). Among the numerous carbon materials, the graphene-related are the most important. The scientific background for the sensing properties of graphene synthesized either by CVD or cleaving natural graphite is presented. Reduced graphene oxide is a promising sensing material mainly because of its easy production, low-cost, and ability to be suspended to fabricate the device. In addition to its excellent properties, it can also be easily modified by functional groups on its surface.