Recent Advancements in 3-D Printing in Medical Applications

ABSTRACT: Stereolithography (SLA) 3D printing technology is increasingly applied in geomechanics, petroleum engineering, geothermal, and CO2 storage research, particularly in fracture flow and mechanics. To understand the mechanical characteristics of 3D printed materials, we conducted laboratory experiments examining the effect of printing orientation on the properties of three specimens. These specimens were printed using a FormLabs (3B+) 3D printer at layering angles of 0°, 45°, and 90°, with a resolution of 100μm, and sized 1-inch in diameter and 2-inches in length. We performed triaxial compressive tests, ultrasonic elastic wave velocity measurements, and unconfined compressive strength (UCS) tests using an Autolab 1500 test frame. Incremental confining pressures from 1 MPa to 20 MPa were applied to explore static and dynamic mechanical properties. The UCS tests showed that all samples exhibited ductile behavior with similar stiffness and yield strength across different layering angles, demonstrating a stiffness of approximately 4 GPa and compressional wave velocities between 2555-2580 m/s at zero confining pressure. The findings confirm the mechanical and acoustic consistency of the samples, supporting their suitability for advanced geomechanical applications. 1. INTRODUCTION Three-dimensional (3D) printing technology, also known as advanced manufacturing (AM), is a rapidly developing field that has revolutionized manufacturing processes across various industries including aerospace (Richter & Lipson, 2011), automotive (Rahim & Maidin, 2014), healthcare (Logan & Duddy, 1998), petroleum engineering (Li et al., 2021), and geomechanics (Phillips et al., 2021). This technology uses computer-aided design (CAD) to create three-dimensional objects by adding material layer by layer using almost any type of material such as polymers, and ceramics. Thermoplastic urethane and metals can also be employed as raw material (Gopinathan & Noh, 2018). There are several techniques involved in 3D printing, including Fused Deposition Modeling (FDM), Stereolithography (SLA), Selective Laser Sintering (SLS), Digital Light Processing (DLP), Binder Jetting, and Material Jetting. Each technique has its advantages and disadvantages (Jandyal et al., 2022), and the choice of technique depends on the type of object being printed, the desired resolution, and the available materials. With the increasing popularity and availability of 3D printing technology, it is now relatively easy to create custom objects, prototypes, and even entire structures using 3D printing. Among the available techniques, SLA is known for producing high-resolution objects with smooth surfaces. SLA was first developed in the early 1980s by Kodama, 1981 and called Rapid Prototyping (RP).

Precision medicine—which emphasizes customized medicines for specific patients—was developed as a result of data analytics, genetics, and imaging, which defined the unique characteristics of every individual and critiqued generic treatments. Technological advances in medical 3D printing have been predicted to revolutionize the health care industry by facilitating the quick manufacturing of customized medications and treatments. Notwithstanding its limitations, this technology redefines surgical planning and promises significant opportunities in the pharmaceutical and healthcare sectors. The adoption of several 3D printing technologies in the pharmaceutical industry is examined in this article. These technologies include stereo-lithography, pressure-assisted micro-syringe, fused filament fabrication, binder jetting, inkjet printing, and selective laser sintering. Their possible applications in healthcare environments for customized medication are presented. In addition to summarizing upcoming advancements for integration in pharmacies and hospitals, this paper analyzes the current status of fused deposition modeling (FDM) technology in pharmaceutical and medical research, its applications in customized therapies, and its limitations.

Despite 3D food printing being a nascent emerging technology in the food industry, it has a greater potential in fulfilling commercial and consumer needs. 3D printing has been forecasted to be revolutionizing the technology of the future. Various well-known 3D printing technologies are material extrusion, powder bed fusion, binder jetting, material jetting, vat polymerization, sheet lamination, and direct energy deposition. In context with food, not all the printing technologies are suitable for the printing process as food is a complex perishable commodity that often undergoes desired amount of pre- as well as postprocessing operations. Hence, this chapter envisages the major considerations of the food-printing process, material properties, and selectivity of materials that are suitable for specific food 3D printing technologies. Extrusion technology, selective sintering, inkjet printing, binder jetting, and bioprinting are the common 3D printing technologies used for the food-printing process that are distinct based on the mechanism of binding of printed layers. Understanding food printing technology is very crucial in terms of technical and design aspects for delivering 3D-printed food with enhanced levels of customization. Hence, the present chapter provides valuable insights into the working principles, binding mechanism, and system components of 3D food printing technologies. Certainly, this chapter helps in better understanding of food-printing process in upbringing the technology of 3D food printing to the next level. In addition, the future outcomes in designing multihead food printers and their efficiency in food production through 3D printing are also briefed.

3D printing for biomedical applications seems to be a technology that is developing in a wavelike manner. Not long after the first attempts for computer-aided design and manufacturing (CAD/CAM) were made in fields such as mechanical engineering and design, researchers also tried to apply these new possibilities in medicine. Only a few years later, the first patient-specific implants, for example, for the treatment of skull defects, became available. While in the very beginning subtractive technologies such as computerized numeric controlled milling were still used, soon new options for additive manufacturing (AM) started to take off [1]. For biomedical applications, laser-based methods such as selective laser sintering (SLS) or 3D powder printing were mostly used, both of which were mostly limited in the beginning to metals and ceramic materials, respectively. A very important step therefore was the development of fused deposition modeling (FDM) as the first extrusion-based AM technology using polymeric materials. For biomedical applications, manufacturing of porous 3D scaffolds with defined outer and inner morphology and their utilization in tissue engineering was investigated in detail, using FDM of poly(lactic acid) or polycaprolactone. These polymers were also among the first biodegradable materials successfully applied in AM. Probably because of the limitations concerning the applicable materials (most early AM machines could only be operated with a few different materials) and the high price of the devices, even at the beginning of the 21st century only a few groups further investigated AM technologies for medical applications. But the situation has changed dramatically since a variety of cheaper 3D printers have become available, of which many can handle different types of materials, offering the necessary flexibility for new developments. In addition, the breakthrough concerning integration of living cells in the printing process (‘bioprinting’) was achieved using ink-jet as well as extrusion-based technologies, opening up the possibility to directly generate artificial tissues. We have therefore seen a strong increase of publications in the field of 3D printing in medicine in the last couple of years, coming from researchers from all over the world, accompanied by new conferences, solely focused on this topic. Nevertheless, we are still at the beginning of a huge and strong development and nobody knows what will become possible in the future. In my opinion, the following directions are those with the strongest driving force at the moment:

Abstract: Additive manufacturing is a highly effective and versatile technology, especially in the medical sector, due to its customization, material complexity, design flexibility, waste minimization, and ability to fabricate intricate shapes that are cumbersome to manufacture by conventional manufacturing techniques. 4D printing plays a significant role in the medical field, especially in the areas not covered by 3D printing technologies, such as smart implants, devices and tools. Also, 4D printing helps doctors to treat more patients with high accuracy and quality. Hence, this manuscript aims to provide an overview of distinct 3D and 4D printing techniques and their emerging applications in the medical sector. A study of 3D printing technologies is presented by explaining the working principles of distinct 3D printing methods: stereo lithography, fusion deposition modeling, inkjet printing, selective laser sintering, selective laser melting and electron beam melting. In addition, the emerging applications of 3D printing in medical sectors (e.g., bioprinting, surgical guides, pharmaceuticals, prostheses, medical devices, dentistry, physiotherapy, etc.), as well as challenges and the future scope of 3D printing, are also discussed. Further, the concept of 4D printing, the market for both 3D and 4D printing, the benefits of 4D printing, the comparison of 3D and 4D printing, limitations, applications, and the future scope of 4D printing in the medical sector are also covered.

The integration of conductive hydrogels and advanced three-dimensional (3D) printing is a trigger of the development of biomedical sensors for healthcare diagnostics and personalized treatment. Poly(3,4-ethylenedioxythiophene):poly(styr ene sulfonate) (PEDOT:PSS) is a versatile conductive hydrogel materials renowned for its exceptional conductivity and hydrophilicity, and 3D printing technology allows for precise and customized fabrication of electronic components and devices. In this review, we aim to explore the potential of 3D-printed PEDOT/PSS conductive hydrogel in the fabrication of biomedical sensors, with a focus on their distinct characteristics, application potential, and systematic classification. We also discuss the methods for fabricating PEDOT:PSS hydrogel electronic devices by employing 3D printing techniques, including extrusion-based 3D printing technology (fused deposition modeling, direct ink writing, and inkjet printing), powder-based 3D printing technology (selective laser sintering and selective laser melting), and photopolymerization-based 3D printing technology (stereolithography and digital light processing). The applications of 2D/3D-printed PEDOT:PSS hydrogels in biomedical sensors, such as strain sensors, pressure sensors, stretchable sensors, electrochemical sensors, temperature sensors, humidity sensors, and electrocardiogram sensor, are also summarized in this review. Finally, we provide insights into the development of 3D-printed PEDOT:PSS-based biomedical sensors and the innovative techniques for biomedical sensor integration.

Three-dimensional (3D) printing is a rapidly developing technology that has gained widespread acceptance in dentistry. Compared to conventional (lost-wax technique) and subtractive computer numeric controlled methods, 3D printing offers process engineering advantages. Materials such as plastics, metals, and ceramics can be manufactured using various techniques. 3D printing was introduced over three decades ago. Today, it is experiencing rapid development due to the expiration of many patents and is often described as the key technology of the next industrial revolution. The transition to its clinical application in dentistry is highly dependent on the available materials, which must not only provide the required accuracy but also the necessary biological and physical properties. The aim of this work is to provide an up-to-date overview of the different printing techniques: stereolithography, digital light processing, photopolymer jetting, material jetting, binder jetting, selective laser sintering, selective laser melting, and fused filament fabrication. Additionally, particular attention is paid to the materials used in dentistry and their clinical application.

This study evaluates the accuracy of drill guides fabricated in medical-grade, biocompatible materials for static, computer-aided implant surgery (sCAIS). The virtually planned drill guides of ten completed patient cases were printed (n = 40) using professional (Material Jetting (MJ)) and consumer-level three-dimensional (3D) printing technologies, namely, Stereolithography (SLA), Fused Filament Fabrication (FFF), and Digital Light Processing (DLP). After printing and post-processing, the drill guides were digitized using an optical scanner. Subsequently, the drill guide’s original (reference) data and the surface scans of the digitized 3D-printed drill guide were superimposed to evaluate their incongruencies. The accuracy of the 3D-printed drill guides was calculated by determining the root mean square (RMS) values. Additionally, cast models of the planned cases were used to check that the drill guides fitted manually. The RMS (mean ± SD) values for the accuracy of 3D-printed drill guides were—MJ (0.09 ± 0.01 mm), SLA (0.12 ± 0.02 mm), FFF (0.18 ± 0.04 mm), and DLP (0.25 ± 0.05 mm). Upon a subjective assessment, all drill guides could be mounted on the cast models without hindrance. The results revealed statistically significant differences (p < 0.01) in all except the MJ- and SLA-printed drill guides. Although the measured differences in accuracy were statistically significant, the deviations were negligible from a clinical point of view. Within the limits of this study, we conclude that consumer-level 3D printers can produce surgical guides with a similar accuracy to a high-end, professional 3D printer with reduced costs.

Prosthodontics focuses on the design and fitting of dental prostheses. The advent of three-dimensional (3D) printing has revolutionized this field by transitioning from labor-intensive methods to precise, computer-aided techniques. This review assesses the impact of 3D printing on prosthodontics, highlighting technological advancements, applications, clinical outcomes, and future directions. A literature review was conducted on recent advancements in 3D printing technologies and materials, focusing on their precision and customization capabilities in dental prostheses. 3D printing technologies such as fused deposition modelling, stereolithography, selective laser sintering, continuous liquid interface production, digital light processing, and material jetting offer high precision and customization, enhancing the creation of dental implants, crowns, bridges, removable prosthodontics, orthodontic devices, and maxillofacial prosthetics. 3D printing has improved the accuracy, efficiency, and customization of dental prostheses, leading to better patient outcomes. Multimaterial printing technologies like lithography-based ceramic manufacturing enable the integration of various materials in a single print, further advancing the field. Challenges such as material limitations, cost, and technical expertise remain, necessitating ongoing research and development.

Chapter 18 - 3D printing technology in drug delivery

An overview of selective laser sintering 3D printing technology for biomedical and sports device applications: Processes, materials, and applications

This review aims to examine the impact of three-dimensional (3D) printing technologies on enhancing psychiatric pharmacotherapy through facilitating personalized and patient-centered drug delivery. This research specifically addresses problems such as poor medication compliance, polypharmacy, and palatability issues, especially in pediatric and elderly populations. A thorough review of the literature was conducted, focusing on novel advances in 3D printing techniques, including fused deposition modeling (FDM), semisolid extrusion (SSE), stereolithography, inkjet printing, binder jetting, and selective laser sintering (SLS). Selected research highlighted the application of such technologies in developing customized oral drug dosage forms. Emphasis was placed on the exploitation of polymers like Eudragit® E PO, flavor-masking excipients, and their combination with biosensor and artificial intelligence (AI) systems. Case studies were assessed to ascertain their relevance and innovation in the development of psychiatric medications. 3D printing allows the manufacture of tailored psychiatric drugs with greater dosing versatility, taste masking, and the ability to merge several active drug ingredients into a single pharmaceutical form. Patient-friendly dosage forms such as chew gummies and chocolate tablets demonstrated enhanced acceptability. Also, forthcoming technologies such as 4D printing and AI-driven biosensors yield intelligent, interactive drug release systems that are specific to individual physiological or behavioral inputs. 3D printing represents a paradigm-shifting advance in psychiatric care, offering solutions to long-standing treatment compliance and fixed-dose challenges. Although regulatory and scalability challenges persist, the intersection of pharmaceutical engineering, material science, and artificial intelligence creates an encouraging platform for the future of precision mental care therapies.

Personalized medicine has the potential to revolutionize the healthcare sector, its goal being to tailor medication to a particular individual by taking into consideration the physiology, drug response, and genetic profile of that individual. There are many technologies emerging to cause this paradigm shift from the conventional “one size fits all” to personalized medicine, the major one being three-dimensional (3D) printing. 3D printing involves the establishment of a three-dimensional object, in a layer upon layer manner using various computer software. 3D printing can be used to construct a wide variety of pharmaceutical dosage forms varying in shape, release profile, and drug combination. The major technological platforms of 3D printing researched on in the pharmaceutical sector include inkjet printing, binder jetting, fused filament fabrication, selective laser sintering, stereolithography, and pressure-assisted microsyringe. A possible future application of this technology could be in a clinical setting, where prescriptions could be dispensed based on individual needs. This manuscript points out the various 3D printing technologies and their applications in research for fabricating pharmaceutical products, along with their pros and cons. It also presents its potential in personalized medicine by individualizing the dose, release profiles, and incorporating multiple drugs in a polypill. An insight on how it tends to various populations is also provided. An approach of how it can be used in a clinical setting is also highlighted. Also, various challenges faced are pointed out, which must be overcome for the success of this technology in personalized medicine.

Three-dimensional (3D) printing is an additive manufacturing technique, which is based on the addition of layers of material to each other according to 3D geometric data, allowing for the rapid transition of the designed parts to the production phase. In the 3D printing technique, no material is wasted, and no mold is required as in other traditional manufacturing methods such as plastic injection, casting, and machining. In this method, free-form parts can be practically produced, and the production of a new part having different geometries can be carried out quickly. Three-dimensional printing is much more suitable for the production of prototypes and custom-made designs than serial production. The variety of materials used in the 3D printer technology is continuously increasing. Today, plastic, metal, composite, and organic materials can be used in 3D printing. Development of the 3D technology enables us to produce parts with different design features. The most common of these technologies are known as fused deposition modeling (FDM), stereolithography (SLA), digital light processing (DLP), and selective laser sintering (SLS). In general, they are all based on the principle of additive layer manufacturing. Three-dimensional printing is also ideal for the creation of complex anatomical models and the production of biomedical devices with free-form geometry. Three-dimensional printers can save cost and time and enable clinical trial devices to be produced and used more frequently. Considering that the production of some of the medical devices is quite challenging due to the small size and complicated structure, the effectiveness of the 3D printing method becomes much more visible. In this chapter, different 3D printing methods and related materials used in the biomedical field are explained and critical examples from recent scientific studies are given. In addition, a number of practical works including 3D printing in biomedical engineering have been reviewed and a preliminary assessment of the use of 3D printers in future biomedical studies has been made.

The application of three-dimensional (3D) printing in medicine has increased rapidly in the last few years. Various new commercial 3D printers and 3D bioprinters are introduced into the current market. 3D printing scientific community has witnessed a rapid growth in the application of 3D printing for various medical needs. There has been a research advancement in 4D printing with a widened scope of 3D bioprinting. The growing demand for 3D printing and its use for commercial and industrial purposes in medical technology have facilitated the need for introduction of new international standards and regulations. The need for organ replacement has generated curiosity and competition among researchers to race for organ 3D printing, which can be identified with increased publications and patents that are filed in recent years. Hence, there is a need to update the readers with the latest information. The second edition of this chapter updates the contents of first section to fourth section with current information and some modified pictorial representations. New section describes the relevance of the new chapters added to this edition and updates the readers with insights on advancement of 3D printing in the last decade. Briefly, this chapter introduces the reader with a brief history of 3D printing in medical technology, components of 3D printing, 3D bioprinting, organ 3D bioprinting, advantages of 3D printing with current challenges and commercially available 3D printers in the current market. New sections introduced in this edition detail about the ASTM and ISO standards that are used for 3D printing in medicine, the regulatory framework with current challenges, ethical and social concerns with the current 3D printing scientific community, and the importance of intellectual property in safeguarding the interests of the innovators.