3D Printing multifunctionality: structures with electronics

Three-dimensional (3D) printing technology in medicine is one of the new and innovative technology for fabricating 3D models of complex anatomical structures that can be observed both visually and haptically. Patient-specific 3D models fabricated through this process are currently being used for various purposes, including surgical simulation, training, and medical education. Most of the personal use/low-end desktop 3D printers that are becoming widespread are fused deposition modeling (FDM) 3D printers. Compared to professional/high-end 3D printers, the price of the personal use/low-end desktop FDM 3D printer itself, filament, and running costs are lower; it can lower the economic bottleneck for introducing 3D printing technology into clinical practice, such as surgical simulation. With a desktop FDM 3D printer and a general-purpose PC, anyone can now rapidly fabricate 3D models on their own without having to rely on 3D printing labs and specialized technicians. However, it is also true that FDM 3D printers, due to their mechanical characteristics, encounter many difficulties and problems that emerge during the 3D printing process. Knowledge, know-how, and tips about FDM 3D printers have been introduced in various media, and it has become easy to know about them worldwide via the Internet. However, there has been no comprehensive technical review to date to produce osseous 3D models for use in oral and maxillofacial surgery. In this report, to create 3D models according to the characteristics of maxillofacial and oral surgery, we enable surgeons themselves to create 3D models smoothly by presenting ideas for CT scanning, points to note when exporting Digital Imaging and Communications in Medicine (DICOM) image data, how to create optimal stereolithography (STL) models, and problems and solutions for 3D printing.

Introduction and backgroundThree dimensional (3D) printing has gained popularity in the medical field because of increased research in the field of haptic 3D modeling. We review the role of 3D printing with specific reference to liver directed applications.MethodsA literature search was performed using the scientific databases Medline and PubMed. We performed this in-line with the PRISMA [20] statement. We only included articles in English, available in full text, published about adults, about liver surgery and published between 2005 and 2015. The 3D model of a patient's liver venous vasculature and metastasis was prepared from a CT scan using Osirix software (Pixmeo, Gineva, Switzerland) and printed using our 3D printer (MakerBot Replicator Z18, US). To validate the model, measurements from the inferior vena cava (IVC) were compared between the CT scan and the 3D printed model.ResultsA total of six studies were retrieved on 3D printing directly related to a liver application. While stereolithography (STL) remains the gold standard in medical additive manufacturing, Fused Filament Fabrication (FFF), is cheaper and may be more applicable. We found our liver 3D model made by FFF had a 0.1 ± 0.06 mm margin of error (mean ± standard deviation) compared with the CT scans.Conclusion3D printing in general surgery is yet to be thoroughly exploited. The most relevant feature of interest with regard to liver surgery is the ability to view the 3D dimensional relationship of the various hepatic and portal veins with respect to tumor deposits when planning hepatic resection.Systematic review registration number: researchregistry1348.

This paper investigates the feasibility of manufacturing hydraulic fittings using additive manufacturing (AM) technologies, specifically Fused Deposition Modeling (FDM) and Stereolithography (SLA). The study addresses the environmental challenge of material waste in conventional fitting production by exploring 3D printing as an alternative manufacturing method. Hydraulic fittings were designed using CAD software: SolidWorks 2022 and fabricated using FDM with PETG (Polyethene Terephthalate Glycol) material and SLA with UV-sensitive photopolymer resin. In present studies, on-destructive leak testing was conducted in accordance with PN-EN 1254-4 and PN-EN 1254, at pressures ranging from 0.1 to 1.0 bar. Dimensional accuracy analysis revealed shrinkage of approximately 1% for SLA-printed parts and 2% for FDM-printed parts. Microscopic examination at 50× and 80× magnification showed superior thread quality in SLA samples compared to FDM, which exhibited visible layer separation and material porosity. Leak testing demonstrated that while the brass reference fitting maintained complete seal integrity, both 3D-printed variants failed to achieve leak tightness under operational pressures, with structural failure occurring at 1.0 bar during tightening. The study showed that FDM with PETG material and SLA with UV-sensitive photopolymer resin, despite achieving acceptable dimensional tolerances (±1-2%), do not meet hydraulic leak tightness requirements at pressures exceeding 0.5 bar in their raw state after printing. The results suggest that alternative material formulations (e.g., carbon fiber-reinforced PEEK for FDM or epoxy engineering resins for SLA) warrant further investigation. Potential avenues for improvement include advanced surface treatment, optimization of printing parameters, and modifications to thread geometry to reduce interthread gaps.

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.

Recent developments in three-dimensional (3D) printing technology offer immense potential in fabricating scaffolds and implants for various biomedical applications, especially for bone repair and regeneration. As the availability of autologous bone sources and commercial products is limited and surgical methods do not help in complete regeneration, it is necessary to develop alternative approaches for repairing large segmental bone defects. The 3D printing technology can effectively integrate different types of living cells within a 3D construct made up of conventional micro- or nanoscale biomaterials to create an artificial bone graft capable of regenerating the damaged tissues. This article reviews the developments and applications of 3D printing in bone tissue engineering and highlights the numerous conventional biomaterials and nanomaterials that have been used in the production of 3D-printed scaffolds. A comprehensive overview of the 3D printing methods such as stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), and ink-jet 3D printing, and their technical and clinical applications in bone repair and regeneration has been provided. The review is expected to be useful for readers to gain an insight into the state-of-the-art of 3D printing of bone substitutes and their translational perspectives.

Three-dimensional (3D) printing allows for the design and printing of more complex designs than traditional manufacturing processes. For the manufacture of personalised medicines, such an advantage could enable the production of personalised drug products on demand. In this study, two types of extrusion-based 3D printing techniques, semi-solid syringe extrusion 3D printing and fused deposition modelling, were used to fabricate a combi-layer construct (combi-pill). Two model drugs, tranexamic acid (water soluble, rapid release) and indomethacin (poorly water-soluble, extended release), were printed with different geometries and materials compositions. Fourier transform infrared spectroscopy results showed that there were no interactions detected between drug-drug and drug-polymers. The printed combi-pills demonstrated excellent abrasion resisting properties in friability tests. The use of different functional excipients demonstrated significant impact on in vitro drug release of the model drugs incorporated in two 3D printed layers. Tranexamic acid and indomethacin were successfully 3D printed as a combi-pill with immediate-release and sustained-release profiles, respectively, to target quick anti-bleeding and prolonged anti-inflammation functions. For the first time, this paper systematically demonstrates the feasibility of coupling syringe-based extrusion 3D printing and fused deposition modelling as an innovative platform for various drug therapy productions, facilitating a new era of personalised combi-pills development.

Mechanical properties of 3D printed specimen using FDM (Fused deposition modelling) and SLA (Stereolithography) technologies

The purpose of this paper is to make an analysis of the advanced technologies for 3D printing of pharmaceutical products for personalised medicine.A review of the basic 3D printing methods used in pharmaceutical technologies is conducted. The main types of printed solid dosage forms are examined, along with the primary advantages and disadvantages of 3D printing compared to conventional drug production. Each method is evaluated in terms of working principles, material compatibility, advantages, and limitations.Revealed that stereolithography (SLA), selective laser sintering (SLS), fused deposition modelling (FDM), ink-jet printing (IJP), and semi-solid extrusion (SSE) are the most suitable 3D printing processes for producing pharmaceutical products. The combination of two methods ensures better results, as illustrated by examples of the main types of printed solid dosage forms.The 3D printing technologies for production of pharmaceutical products present several limitations such as: uneven geometries and porous structures, necessitating the fabrication of larger and irregular dosage forms to ensure the required drug load for the patient; degradation of thermolabile drugs during FDM process; increased hardness of FDM produced tablets impairing drug release.The advanced 3D printing technologies offer the ability to produce new formulations easily through simple design modifications in software, compared to conventional manufacturing. They enable the design of flexible formulations with complex release profiles and the personalised production of dosage forms tailored to individual patients.3D printing has emerged as a transformative technology in pharmaceutical manufacturing, enabling the production of personalised dosage forms with precise drug loading, tailored release profiles, and complex geometries. The review not only summarises the main applicable techniques but also highlights the most recommended methods for personalised pharmacotherapy. The versatility and adaptability of 3D printing provide promising solutions for personalised therapy, emergency drug manufacturing, and enhanced patient compliance, marking a significant step toward decentralised, digital pharmaceutical production.

Intra-hospital patient-specific 3D printed surgical guide for patients with thoracic scoliotic deformities, the collaboration between engineer and surgeon.

Chapter 2 - 3D printing and nanotechnology

4D printing is now commonly defined as a targeted evolution of a 3D printed structure to change its shape, properties, and functionality over time. In direct 4D printing this targeted evolution is embedded in the structure during the 3D printing process. A heat stimulus can be used to trigger a transition between two states of a printed shape memory polymer. 3D and 4D printing have greatly expanded the design space of a variety of engineering parts. However, 3D printed parts often show anisotropic behavior due to layering, especially when using fused filament fabrication. Here, it is shown how direct 4D printing on a fused filament fabrication system can be used to create deployable polymer wave springs. By introducing a pattern of multimaterial bilayer actuators into the wave spring, it can be printed flat and deployed to a designed spring shape through a thermal stimulus. This method eliminates the typical layering issues found in 3D printed springs due to printing at angles. Additionally, it reduces the print time and support material consumption. These findings show the great potential of direct 4D printing on 3D printers using fused filament fabrication to create functional, 4D printed components with complex geometry, such as polymer springs.

This study compares two fabrication methods for flexible strain sensors intended for wearable applications: a screen-printed Thermoplastic Polyurethane—Carbon Nanofiber (TPU-CNF) composite and a commercially available conductive TPU filament. TPU was selected as the substrate for its flexibility and compatibility with additive manufacturing techniques, including fused deposition modeling (FDM) and screen printing. The conductive ink was prepared by dissolving TPU pellets and carbon nanofibers in a solvent, then screen-printed onto TPU substrates produced by FDM. For comparison, the Filaflex conductive filament was 3D printed onto the same dielectric TPU in matching geometries. All sensors were fabricated on dogbone-shaped samples following the ASTM D638 Type IV standard[1]. Three electrode patterns—parallel lines, zigzag, and inter-digitated—were evaluated to study the effects of geometry on sensor behavior. Electrical resistance, stress-strain response, and cyclic hysteresis were measured for both materials. The screen-printed TPU-CNF sensors showed lower stiffness and good electrical response under strain, offering an alternative to the more rigid commercial filament. This work provides insight into how the fabrication approach and material selection influence performance in stretchable sensors, contributing to the development of more flexible and reliable options for wearable electronics.

Three-dimensional (3D) printing is a process for creating 3D objects with various geometries using digital modeling, and it is widely used in the construction and medical industries. In the field of pharmacy, 3D printers were introduced as a suitable manufacturing method in response to the increasing need for “personalization.” Since the first 3D printed drug, Spritam®, was approved by the Food and Drug Administration (FDA) in 2015, 3D printer technology has evolved through considerable research. The 3D printing methods are classified into selective laser sintering, inkjet printing, stereolithography, digital light processing, and fused deposition modeling (FDM) according to the printing method. Among them, FDM, which is a method of extruding filaments through a nozzle, is the most widely used 3D printer method in pharmaceuticals. This review paper covers the detail content of manufacturing drugs by FDM. Owing to its ease of use and relatively low price, many studies have focused on FDM 3D printers. In this review paper, we concretely investigate a series of FDM procedures and parameters and introduce many studies that used FDM 3D printers to control the release, to make novel dosage form, and to deliver the customized doses. FDM is completely different from traditional drug manufacturing methods, and it is expected to achieve personalization. Once mechanical problems and regulatory barriers are overcome and new developments are made, FDM 3D printers will become a unique and effective way to manufacture patient-customized drugs in the pharmaceutical industry.

Three-dimensional (3D) printing technologies have unparalleled advantages in constructing piezoelectric devices with three-dimensional structures, which are conducive to improving the efficiency of energy harvesting. Among them, fused deposition modeling (FDM) is the most widely used thanks to its low cost and wide range of molding materials. However, as the best piezoelectric polymer, a high electroactive β-phase poly(vinylidene fluoride) (PVDF) piezoelectric device cannot be directly obtained by FDM printing because the β-crystal is unstable at the molten state. Herein, we develop for the first time ionic liquid (IL)-assisted FDM for direct printing of β-PVDF piezoelectric devices. An IL can induce and maintain β crystals during melt extrusion and FDM printing, ensuring that the β-crystal in the printed PVDF device is as high as 98.3%, which is the highest in 3D-printed PVDF as far as we know. Furthermore, the shearing force provided by the FDM facilitates the directional arrangement of the dipoles, resulting in the printed PVDF device having self-polarization characteristics without poling. Finally, the piezoelectric output voltage of the 3D-printed PVDF device is 4.7 times that of the flat PVDF device, and its area current density (17.5 nA cm-2) is more than that of the reported 3D-printed PVDF piezoelectric device in the literature by two orders of magnitude. The one-step 3D printing strategy proposed in this paper can realize the rapid preparation of complex-shaped and lightweight self-polarized β-PVDF-based piezoelectric devices for energy harvesting.

Emergency and disaster medical care often face resource or equipment shortages. 3D printing technology has been proven to be effective in cases with insufficient supply chains. MAYO tubes and stethoscopes are essential components of ABCDE patient examinations; however, 3D-printed variants have not been fully tested. These 3D-printed instruments were substituted and validated in a simulated pre-hospital environment.In total, 26 participants were included in this study. Fifteen clinicians or paramedics with at least 3 years of professional experience and 10 medical students. One student was excluded because he had relevant experience with emergency care. As basic tasks, the placement of MAYO tubes and auscultation with stethoscopes were performed using medical simulators. 3D printed instruments were compared with conventional clinical devices by measuring the time required for the intervention, success rate, and user satisfaction. In the study FFF (Fused Filament Fabrication (FFF), SLS (Selective Laser Sintering (SLS), and SLA (stereolithography) 3D printing were used in this study.The times required for implementation and auscultation were examined for each instrument. There was no significant difference between the MAYO tube (p = 0.798) and the stethoscope (p = 0.676). In the case of stethoscopy, the study investigated the correct diagnosis, and no significant difference was found (p = 0.239), although an interesting trend was observed. Regarding the MAYO tube, the study found no significant difference in correct position formation (p = 0.163). The experience levels of the groups did not influence these factors. However, significant differences in user satisfaction were found in both cases in favour of the conventional versions (p < 0.001).Overall, the results of this study suggest that 3D-printed devices could be suitable replacements for clinic-based devices in emergency situations. The 3D-printed devices did not perform inferiorly at any of the indicated points compared to their classical counterparts. However, the practical applicability of the devices used in this study requires further investigation.