Particle-less reactive inks

Reactive inks are an emerging alternative to nanoparticle-based inks. Traditional particle-based inks are made by dispersing micron- to nano-sized particles into a solution. When printed, they produce a cluster of particles that require some form of sintering (thermal, plasma, or chemical) to produce a continuous solid structure with good material properties. In contrast, reactive inks generally contain no particles. Instead, they are made by mixing various chemical precursors (such as metal salts, complexing agents, reducing agents, and solvents) and are selected to be shelf-stable, but then react when printed to precipitate a solid. By varying reaction kinetics, heat transfer, and mass transport during printing, it is possible to produce a continuous solid with good material properties at temperatures below 100°C. This chapter will detail the overall mechanisms of reactive inks, their history and progress, and the considerations one must have when designing and then printing a reactive ink for a specific application. The goals of this chapter are to introduce and educate the reader about an emerging field and to inspire new uses of these inks.