3D/4D Printing in Additive Manufacturing: Process Engineering and Novel Excipients

In recent years, additive manufacturing, which is more colloquially referred to as three-dimensional (3D) printing, has seen high-impact implementation in manufacturing applications in areas such as aeronautics, robotics, electronics, industrial goods, and even the food industry. These wide-ranging applications have resulted in a change in focus for biomedical research [1]. 3D printing is a generic term that describes various methods of constructing objects in a layer-by-layer manner. Although the birth of 3D printing dates back to 1984, when Charles Hull invented the first stereolithographic printer, 3D printing started to increasingly change the way in which manufacturing was performed from the year 2000 onward. This chapter will introduce the basic concepts of 3D and 4D printing technologies as they pertain to biomedical applications. In particular, 4D printing (printing of objects with the ability to change over time) has a strong potential for biomedical applications. Patient-specific products such as medical devices, tissue constructs (including muscle structures, bone, and ear tissue), and, eventually, artificial organs may be fabricated using 4D printing [2–6].