Nano-inks can be used in inkjet printers, for printing complex circuitry on flexible substrates, or they can be used as a paste for 3D printers. Microstructures can be 3D-printed, using nano-inks, in a combination of high-resolution plasma printing and subsequent rotogravure printing. In addition, smart multifunctional nano-inks are not only required for the electronic but in other applications, such as for secure inks, for currency or immigration documents. The current challenge for the successful industrial application of nano-inks is in the preparation of a stable dispersion of advanced materials for nano-inks. The functionalization, synthesizing, and theoretical modeling provide the solution for most of the current issues. This book focuses on the fundamental design concepts, promising applications, and future challenges of nano-inks in various areas, such as in optoelectronics, energy, security, and biomedical fields.