Programmable materials: Current trends, challenges, and perspectives

Research into programmable materials has attracted extraordinary interest since the nineties, when the term "programmable" was introduced for the first time. In its widest definition, the term is used to denote materials that are designed to be highly dynamic, either in shape and/or physical/functional properties, on-demand and in a precise, sequential predetermined way. Such unique feature allows them to adapt to various needs and offers new opportunities in several application fields, enabling them to overcome the limitations of traditional materials. The present paper aims to introduce readers to the world of programmable materials, enhance their interest, knowledge, and skills in the field, and provide useful insights and new ideas on how to approach their development and implementation. Accordingly, this paper offers an overview and discussion of current state-of-the-art and recent progress up to future perspectives. First, the historical evolution and definition of these materials as well as the types of programmable properties achievable are presented. Then, the different programming strategies that could be used to tune material properties are covered, with an emphasis on the constituent materials, applied stimuli, and geometrical arrangements. Finally, real-world applications, ongoing challenges, and future directions for this exciting class of materials are discussed.