Three-dimensional plotting of biomaterials (also known as bioprinting) has been a major milestone for scientists and engineers working in nanobiotechnology, nanoscience, and nanomedicine. It is typically classified into two major categories, depending on the plotting principle, as contact and noncontact techniques. This article focuses on the working principles of contact and noncontact printing methods along with their advantages, disadvantages, applications, and challenges. Contact printing methods include micro-plotter, pen printing, screen printing, nanoimprint printing, flexography printing, and gravure printing. Noncontact printing methods include extrusion printing, droplet printing, laser-based polymerization, and laser-based cell transfer. The wide variety of printable biomaterials, such as DNA, peptides, proteins, lipids, and cells, also are discussed.

Additive manufacturing (AM) technologies print three-dimensional (3D) parts through layer-by-layer deposition based on the digital input provided by a computer-aided design file. This article focuses on the binder jet printing process, common biomaterials used in this AM technique, and the clinical applications relevant to these systems. It reviews the challenges and future directions of binder-jetting-based 3D printing.

The use of 3D bioprinting techniques has contributed to the development of novel cellular patterns and constructs in vitro, ex vivo, and even in vivo. There are three main bioprinting techniques: inkjet printing, extrusion printing (also known as bioextrusion), laser-induced forward transfer (LIFT) printing, which is also known as modified LIFT printing, matrix-assisted pulsed-laser evaporation direct write, and laser-based printing (laser-assisted bioprinting, or biological laser printing). This article provides an overview of the LIFT process, including the LIFT process introduction, different implementations, jetting dynamics, printability phase diagrams, and printing process simulations. Additionally, materials involved during LIFT are introduced in terms of bioink materials and energy-absorbing layer materials. Also, the printing of single cells and 2D and 3D constructs is introduced, showcasing the current state of the art with the ultimate goal for tissue- and organ-printing applications.

Inkjet printing is extremely precise in terms of the ejected microdroplets (picoliter volume), contributing an unparalleled lateral resolution. Additionally, the benefits of high-speed deposition, contactless ink delivery, and the use of a range of ink materials endorse this technique as suitable for high-throughput 3D manufacturing. This article provides an overview of inkjet 3D printing (also referred to as 3D inkjetting). It then highlights the major components and accessories used in commercial and laboratory-based 3D inkjet printers. Next, the article describes the process physics of the transient phenomena involved in both binder-jetting- and direct-inkjetting-based 3D printing. It then discusses the scope and advantages of 3D inkjetting in the manufacturing of metallic, ceramic, and polymer-based biomaterials. The article also discusses several approaches and methodologies to examine the in vitro cytocompatibility and in vivo biocompatibility of both binder-jetted and direct-inkjetted scaffolds for biomedical applications. Finally, it discusses the challenges and troubleshooting methodologies in 3D inkjetting of biomaterials.

Microvalve jetting, with its advantages of low cost, ease of operation, high printing speed, and ability to process living cells with high viability, has been primarily used for fabricating high-throughput drug-screening models, in vitro cellular structures for fundamental cell biology research, and cell-laden structures for regenerating tissues or organs in the human body after disease or trauma. This article provides an overview of microvalve jetting of biomaterials, including operational parameters. The jetting technologies covered are inkjet printing, microvalve jetting, and laser-assisted jetting. The parameters covered include nozzle size (nozzle inner diameter), pneumatic pressure, valve-opening time, and printing speed of microvalve jetting. Subsequently, the article discusses biomaterials for microvalve jetting in terms of biomaterial definition, required properties for a suitable biomaterial, currently used biomaterials, and cells and cellular structures. Additionally, applications of microvalve jetting in biomedical engineering are presented, which include cellular and RNA analysis, high-throughput drug screening, and tissue engineering.

This article focuses on the pneumatic extrusion-based system for biomaterials. It provides an overview of additive manufacturing (AM) processes, followed by sections covering steps and major approaches for the 3D bioprinting process. Then, the article discusses the types, processes, advantages, limitations, and applications of AM technology and extrusion-based approaches. Next, it provides information on the research on extrusion-based printing. Finally, the article provides a comparison of the extrusion-based approach with other approaches.

This article discusses electrospinning as a method for obtaining nanofibers, some of the challenges and limitations of the technique, advancements in the field, and how it may be used in key functional applications. The key drawbacks of traditional electrospinning processes include relatively slow speed of nanofiber production, low product yield, and relatively high cost. The article also addresses novel high-throughput techniques and methods designed for the scalable synthesis of nanofibers and nanofibrous mats that are of reasonable cost.

This article reviews the corrosion interactions between biomedical alloys, in particular iron-base, titanium-base, and cobalt-base alloys, in complex geometries and in applications where there are significant cyclic stresses and potential for wear and fretting motion. It discusses the nature of these metal surfaces and their propensity for corrosion reactions when combined with similar or different alloys in complex restrictive environments within the human body and under loading conditions. The article describes the factors that influence mechanically assisted crevice corrosion. It reviews the tests developed to investigate the aspects of mechanically assisted corrosion of metallic biomaterials: the scratch test and the in vitro fretting corrosion test.

This article provides an overview of the fundamentals of tribology. It describes the advantages, disadvantages, and applications of the pin-on-disk method, which is the most commonly used configuration for testing biomaterials and for the reproducible measurement of friction and wear. The article illustrates a practical tribocorrosion setup that allows a user to perform wear tests in corrosive environments under well-defined electrochemical conditions and at controlled temperature. It explains the effect of changes in electrical contact resistance on tribological mode. The article discusses various in vivo environmental conditions in tribological tests. Some typical examples of biomaterials testing are also provided.

This article describes mechanical/electrochemical phenomena related to in vivo degradation of metals used for biomedical applications. It discusses the properties and failure of these materials as they relate to stress-corrosion cracking (SCC) and corrosion fatigue (CF). The article presents the factors related to the use of surgical implants and their deterioration in the body environment, including biomedical aspects, chemical environment, and electrochemical fundamentals needed for characterizing CF and SCC. It provides a discussion on the use of metallic biomaterials in surgical implant applications, such as orthopedic, cardiovascular surgery, and dentistry. It addresses key issues related to the simulation of an in vivo environment, service conditions, and data interpretation. These include the frequency of dynamic loading, electrolyte chemistry, applicable loading modes, cracking mode superposition, and surface area effects. The article explains the fundamentals of CF and SCC, and presents the test findings from laboratory, in vivo, and retrieval studies.

This article reviews the understanding of corrosion interactions between alloys in complex geometries and in applications where there are significant cyclic stresses and potential for wear and fretting motion. These alloys include iron-base, titanium-base, and cobalt-base alloys. The article discusses the surface characteristics and electrochemical behavior of metallic biomaterials. It summaries the clinical context for mechanically assisted corrosion and describes mechanically assisted crevice corrosion. There have been several tests developed to investigate aspects of mechanically assisted corrosion. The article also explains the scratch test and the in vitro fretting corrosion test.

This article provides information on biomedical aspects such as active biological responses and the chemical environment characterizing the internal physiological milieu, as well as electrochemical fundamentals needed for characterizing corrosion fatigue (CF) and stress-corrosion cracking (SCC). It discusses some of the mechanical and electrochemical phenomena related to the in vivo degradation of materials used for biomedical applications. These materials include stainless steels, cobalt and titanium-base alloy systems, and dental amalgam. The article addresses key issues related to the simulation of the in vivo environment, service conditions, and data interpretation. The factors influencing susceptibility to CF and SCC are reviewed. The article describes the testing methodology of CF and SCC. It also summarizes findings from laboratory testing, in vivo testing and retrieval studies related to CF and SCC.

Biomaterials are the man-made metallic, ceramic, and polymeric materials used for intracorporeal applications in the human body. This article primarily focuses on metallic materials. It provides information on basic metallurgy, biocompatibility, chemistry, and the orthopedic and dental applications of metallic biomaterials. A table compares the mechanical properties of some common implant materials with those of bone. The article also provides information on coatings, ceramics, polymers, composites, cements, and adhesives, especially where they interact with metallic materials.

This article focuses on the use of noble and precious metals for biomedical applications. These include gold, platinum, palladium, ruthenium, rhodium, iridium, and osmium. The physical and mechanical properties of noble and precious metals are presented in tables. A brief discussion on the ancient history of noble and precious metal use in dentistry is provided. The article discusses the use of direct gold dental filling materials, direct silver dental filling materials, traditional amalgam alloys, high-copper amalgam alloys, and gallium alloys in biomedical applications. It also provides information on gold coatings and iridium oxide coatings for stents.

Piezoelectric jetting is a common form of additive manufacturing technology. With the development of material science and manufacturing devices, piezoelectric jetting of biomaterials has been applied to various fields including biosensors, tissue engineering, deoxyribonucleic acid (DNA) synthesis, and biorobots. This article discusses the processes involved in piezoelectric jetting of biosensors and biorobots and the applications of piezoelectric jetting for tissue engineering and producing DNA. In addition, it reviews the challenges and perspectives of piezoelectric jetting.