3D Printing in Medicine

Deepak M. Kalaskar

• Publisher: Woodhead Publishing
• Year: 2017
• Topic: Technology & Engineering
• eBook ISBN:
  9780081007266
• Subtopic: Biomedical Science
• Index: Technology & Engineering

3D Printing in Medicine examines the emerging market of 3D-printed biomaterials and its clinical applications. With a particular focus on both commercial and premarket tools, the book looks at their applications within medicine and the future outlook for the field. The book begins with a discussion of the fundamentals of 3D printing, including topics such as materials, and hardware. Chapters go on to cover applications within medicine such as computational analysis of 3D printed constructs, personalized 3D printing and 3D cell and organ printing. The concluding chapters in the book review the applications of 3D printing in diagnostics, drug development, 3D-printed disease models and 3D printers for surgical practice. With a strong focus on the translation of 3D printing technology to a clinical setting, this book is a valuable resource for scientists and engineers working in biomaterial, biomedical, and nanotechnology based industries and academia. - Provides a comprehensive and authoritative overview of all the medical applications of 3D printing biomaterials and technologies - Focuses on the emerging market of 3D printed biomaterials in clinical applications - Reviews both commercial and under development materials, tools, their applications, and future evolution

1

Introduction to 3D printing in medicine

Uday Kiran Roopavath and Deepak M. Kalaskar, University College London, London, United Kingdom

Abstract

Three dimensional (3D) printing is the latest innovative technology that has been revolutionary in engineering, product design, and manufacturing. 3D printing allows the rapid conversion of information from digital 3D models into physical objects. In this chapter, we focus on introducing the fundamentals of 3D printing technology and its applications in medicine.

Keywords

additive manufacturing; materials in 3D printing; 3D bioprinting; miniature-tissues; drug screening

Chapter Outline

1.1 3D printing is the latest industrial revolution 1

1.1.1 Brief history of 3D printing 2

1.1.2 Basic components of 3D printing 3

1.2 3D bioprinting in medicine 6

1.2.1 3D bioprinting approaches 7

1.2.2 Feasibility of organ printing technology 9

1.2.3 In vivo behavior of 3D printed organ constructs 10

1.3 Advantages of 3D printing for medicine 11

1.3.1 Applications of 3D printing in medicine 11

1.3.2 Limitations and challenges of 3D printing 15

1.4 Future of 3D printing in medicine 15

References 17

1.1 3D printing is the latest industrial revolution

Three dimensional (3D) printing is the latest innovative technology that has been revolutionary in engineering, product design, and manufacturing and has a great promise to revolutionalize medicine. 3D printing allows the rapid conversion of information from digital 3D models into physical objects.

3D printing is also widely known by other terms such as additive manufacturing (AM) or rapid prototyping (RP) or solid free form fabrication or layered manufacturing. This technology has been widely applied in various engineering and biomedical fields [1]. In conventional manufacturing techniques, material is removed from a solid block, often by milling, and so it is known as subtractive manufacturing. Conversely, 3D printing is a generic term that describes various methods of constructing objects in a layer-by-layer fashion (hence the term “additive manufacturing”). The original concept, powder-bed printing, was developed at MIT and involved printing a liquid binder onto a thin powder bed. Subsequent developments in technology mean there are now several types of 3D printers available, and all have potential application for pharmaceutical products. In all cases, the object to be printed is created using computer-aided-design (CAD) software package which is then exported as a file to be printed. The exported file splits the 3D object into a series of layers—the object is then printed layer by layer. The technology involves printing a single material or a combination of multiple materials in a layer-by-layer manner, regulating the shape of every individual layer, eventually resulting in a complex 3D structure with limited restrictions on its spatial arrangement. Recently, 3D printing has advanced to the stage of printing conventional biocompatible materials and even viable cells into complicated 3D functional tissue constructs (generally called “bioprinting”) [2], with the potential ability to develop desired tissues and organs that are suitable for numerous biomedical applications, such as organ transplantation or cancer drug screening [2,3].

1.1.1 Brief history of 3D printing

The origins of conventional 3D printing can be traced back to the 1980s when stereolithography (SLA), the first ever 3D printing technology, was invented by Hull [4]. SLA is a process in which photons from an ultraviolet (UV) laser light source is targeted onto the surface of a photo-curable liquid monomer bath and scanned in different patterns. The scanned monomers are sensitive to light, hence can be crosslinked by using a suitable light source. When exposed to photons these monomers harden to form the required 2D cross-sections, while the unexposed monomers remain unchanged in the bath. Hull was also the first person to find a way to use a CAD file to interact with the RP system in order to develop computer-modeled objects. Hull’s patent was accepted in 1986, which was the first patent for a 3D printer. 3D Systems, a company founded by Hull, focused on commercializing SLA technology, which were the first commercial 3D printers. Two additional 3D printing technologies were considered and modified around the time of the emergence of SLA. Selective laser sintering (SLS) was invented by Deckard who was a graduate student at the University of Texas, Austin in Beaman’s group [5]. SLS uses powder materials spread on a build platform where a selected laser sinters the powder in specific areas based on the digital data supplied in a CAD file [1]. A familiar powder bed-based concept formed the basis of another important technology, Inkjet 3D printing, by Sachs’ group at the Massachusetts Institute of Technology. Inkjet printing involves the printing of a binder and powder in successive layers based on digital CAD information. Using this technique, complex shapes in polymer, metal, and ceramic objects could be printed. Nevertheless, post-processing or sintering steps were often compulsory to enhance the ultimate strength of the fabricated parts [6]. Scott and Lisa Crump introduced another modified 3D printing technology called fused deposition modeling (FDM). FDM involves heating an amorphous thermoplastic filament to a viscous semi-liquid state, which is then extruded and slowly deposited through an aperture onto a non-sticky substrate to build objects layer-by-layer based on the information supplied through a CAD file [2]. Later, Sanders released the first 3D printer involving inkjet printing of thermoplastic polymers [3]. Objects with fine structural features could be manufactured easily using this approach. The abovementioned technologies are the notable initial 3D printing technologies that were primarily based on RP for design confirmation and visualization.

Over the past 15 years, a range of innovative technologies have evolved that have transformed the idea of RP to AM, where objects fabricated by a 3D printer can be used directly for a variety of biomedical applications. In the case of metallic biomaterials, laser-based or electron beam-based technologies have immensely revolutionized industrial applications of these printing technologies. For biomedical applications, many novel fabrication techniques based on direct ink writing, robotic-assisted printing and laser-assisted bioprinting are all in use for varied applications [7]. In 2009, a new international committee dedicated to the specification of standards for additive manufacturing called American Society for Testing and Materials (ASTM) was formed [8]. This committee, known as ASTM F42, formulated a categorization of all 3D printing technologies into seven major groups briefly explained in Table 1.1. The major categories of well-known 3D printing technologies according to ASTM standards with respective vendors that fit within each category along with few examples of materials used for application in medicine are summarized in Table 1.2.

Table 1.1

Specialized AM Standards specific to material, process, or application

Standards	Category AM Standards (specific to material category or process category)	Applications	Test methods
Feedstock materials	Metal powders, ceramic powders, photopolymer resins, polymer powders, polymer filaments, etc.	Aerospace, medical, automotive, etc.	Mechanical test methods, post-processing methods, NDE/NDT methods, bio-compatibility test methods, chemical test methods, etc.
Process/equipment	Material jetting, powder bed fusion, binder jetting, directed energy deposition, material extrusion, sheet lamination, vat photopolymerization, etc.	Aerospace, medical, automotive, etc.	Mechanical test methods, post-processing methods, NDE/NDT methods, bio-compatibility test methods, chemical test methods, etc.
Finished parts	Titanium alloy, paper, sand, nylon, ABS, aluminum alloy, nickel-based alloy, etc.	Aerospace, medical, automotive, etc.	Mechanical test methods, post-processing methods, NDE/NDT methods, bio-compatibility test methods, chemical test methods, etc.

Table 1.2

3D printing technologies with examples of materials for application in medicine and commercial vendors respectively

Types of 3D printing technologies	Examples of materials for processes application in medicine	Examples of commercial vendors
Vat photopolymerization	A large variety of photocurable polymers	Stereolithography from 3D Systems Bioplotters from Envisiontec Large Area Maskless Photopolymerization from DDM Systems Lithoz Lithograph...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of contributors
• 1. Introduction to 3D printing in medicine
• 2. 3D printing families: Laser, powder, nozzle based techniques
• 3. Materials for 3D printing in medicine: Metals, polymers, ceramics, hydrogels
• 4. Computational analyses and 3D printed models: A combined approach for patient-specific studies
• 5. Patient specific in situ 3D printing
• 6. 3D printed in vitro disease models
• 7. 3D printers for surgical practice
• 8. 3D printed pharmaceutical products
• 9. High-resolution 3D printing for healthcare underpinned by small-scale fluidics
• 10. Four dimensional printing in healthcare
• Index