ABSTRACT
Ventricular assist devices (VADs) are complex in all aspects, from design to simulation, prototyping, construction, control, in vitro and in vivo testing, biointegration, and long-term performance, causing minimal negative reactions in the patient. All these aspects are affected by other fundamental points: Materials must be selected to manufacture each component specified in the project, considering the requirements they must meet during the VAD operation. As the design of VADs evolved from pulsatile pumps to axial flow pumps and, later, to centrifugal pumps, the shafts and bearings of these pumps came to play a central role in their performance. Advanced bioceramics have been the natural choice for the construction of bearings used in advanced VAD models, as they fulfill strict quality criteria that include biocompatibility, mechanical strength, and tribological performance. However, designers involved in the development of VADs usually have only superficial knowledge about the different types of advanced ceramics. Additionally, they rarely understand that the performance of these materials depends not only on their composition and surface finishing, as suggested by common sense, but also on the microstructure, which results from the various stages of the manufacturing process. This review is aimed at these professionals and intends to fill this knowledge gap, describing the characteristics of advanced ceramics potentially capable of meeting the requirements for use in the manufacture of centrifugal pump bearings for VADs. Microstructural characteristics and their relationship with the properties of advanced ceramics are described. Finally, the most suitable manufacturing processes to produce ceramic bearings for VADs are presented, highlighting how each processing step affects the microstructure and, consequently, the properties and performance of these materials. For the reader who wishes to deepen their knowledge on specific topics in this chapter, key references are indicated throughout the text.10.1 Shafts and Bearings in VADs: Characteristics and Demands
