Fabricating flexible conductive structures by printing techniques and printable conductive materials

Flexible electronics have attracted great attention with the enhanced flexibility of electronic devices, which could be used as flexible sensors, flexible batteries, electronic skin, soft robots, and so on. They play a crucial role in realizing human-machine interactions and developing wearable devices. The stable flexible conductive structure (FCS) with bending, folding, and stretching is necessary for these flexible electronics. As a type of solution processing method, printing techniques have been widely used in fabricating FCSs by printing conductive inks on flexible surfaces. The printable conductive materials are critical for fabricating FCSs by the printing techniques. In this review, the printing techniques for fabricating FCSs are described with inkjet printing, extrusion printing, screen printing, gravure printing, and micro-contact printing. Moreover, the printable conductive materials for fabricating FCSs are presented, including organic conductive materials, inorganic conductive materials, and metallic materials. Meanwhile, the synergistic effects for fabricating FCSs are discussed among printing techniques, printable conductive materials, and flexible substrates. Finally, the remaining challenges and prospects are proposed for fabricating FCSs, which would provide a valuable reference for constructing flexible electronics.