Additive manufacturing in medical sciences: past, present and the future

Additive manufacturing (AM) is a novel technique that despite having been around for more than 35 years, has been underutilized. Its great advantage lies in the basic fact that it is incredibly customizable. Since its use was recognized in various fields of medicine like orthopaedics, otorhinolaryngology, ophthalmology etc, it has proved to be one of the most promising developments in most of them. Customizable orthotics, prosthetics and patient specific implants and tracheal splints are few of its advantages. And in the future too, the combination of tissue engineering with AM is believed to produce an immense change in biological tissue replacement

Medical Applications for 3D Printing: Recent Developments

This is a review of some of the recent developments in the application of 3D printing to medicine. The topic is introduced with a brief explanation as to how and why 3D is changing practice, teaching, and research in medicine. Then, taking recent examples of progress in the field, we illustrate the current state of the art. This article concludes by evaluating the current limitations of 3D printing for medical applications and suggesting where further progress is likely to be made

Development of a heat flow code to simulate production of a functionally graded material robotic gripper using the additive manufacture process

The additive manufacture process is thermally-complex – many different material mechanisms are occurring due to the heating/cooling cycle that parts are put through when the material is deposited. This complexity is compounded when parts are made from a combination of materials, as in functionally graded material (FGM) parts. To better understand this complexity, a Python™ code has been developed to plot heat flow through the part as material is being deposited. The outputs of such code will highlight the influence of the deposition tool path and indicate to the engineer what areas of a part may require redesigning. A robotic arm gripper is used as a test bed throughout the development of the code

O impacto da impressão 3D em ORL

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2019A utilização da impressão 3D no âmbito da medicina tem vindo a aumentar ao longo dos anos, não só pela sua utilidade demonstrada na criação de próteses personalizadas para cada indivíduo e no planeamento pré-cirúrgico, como também no ensino e formação de jovens profissionais e educação dos doentes. A otorrinolaringologia é uma das especialidades que usufrui dos grandes benefícios deste avanço tecnológico, tratando-se de uma área que aborda uma ampla variedade de problemas, tanto numa vertente médica como cirúrgica. A presente dissertação tem como finalidade reunir e expor as principais contribuições desta tecnologia para a otorrinolaringologia, aprofundando o seu impacto tanto na sua prática como no seu ensino.The use of 3D printing within the field of medicine has been growing over the years, not only because of its demonstrated utility regarding the creation of custom prosthetic implants for each person and pre-operative planning, but also when it comes to the teaching and training of young professionals and the education of patients. Otolaryngology is one of the medical specialties that benefits a lot from this technological advance, being an area that deals with a diverse multitude of problems, both from a medical and surgical standpoint. The goal of this thesis is to gather and expose the main contributions of this technology towards otolaryngology, going in depth on the impact it has both in its practice and in its teaching

Structural and surface degradation of PVDF nanocomposite material

Cílem bakalářské práce je sledování strukturních a povrchových změn polyvinyliden fluoridových nanokompozitních materiálů (PVDF) s nanoplnivy na bázi vermikulit (V), oxid zinečnatý (ZnO) a chlorhexidin (CH). Teoretická část bakalářské práce je řešena formou literární rešerše na téma PVDF, nanokompozitní materiály, degrabilita a biodegrabilita polymerních nanokompozitních materiálů. V rámci experimentální části práce byly připraveny PVDF nanokompozitní filmy metodou ex-situ které byly podrobeny UV-, bio- a ultrazvukové degradaci. PVDF nanokompozitní materiály byly charakterizovány pomocí optické mikroskopie (OM), rentgenové difrakční analýzy (RTG), skenovací elektronové mikroskopie (SEM), infračervené spektroskopie s Furierovou transformací (FTIR), diferenční skenovací kalorimetrie (DSC) a termogravimetrické analýzy (TGA).This work deals with characterisation of structural and surface changes of the polyvinylidene fluoride nanocomposites (PVDF) with nanofillers based on vermiculite (V), zinc oxide (ZnO) and chlorhexidine (CH). Theoretical part is based on the literature review on the theme of PVDF, nanocomposite materials, degrability and biodegrability of polymer nanocomposite materials. In the experimental part were prepared PVDF nanocomposite films by the ex-situ method, which were characterized by optical microscopy, X-ray diffraction analysis (RTG), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).9360 - Centrum nanotechnologiívýborn

Developing an Ear Prosthesis Fabricated in Polyvinylidene Fluoride by a 3D Printer with Sensory Intrinsic Properties of Pressure and Temperature

An ear prosthesis was designed in 3D computer graphics software and fabricated using a 3D printing process of polyvinylidene fluoride (PVDF) for use as a hearing aid. In addition, the prosthesis response to pressure and temperature was observed. Pyroelectric and piezoelectric properties of this ear prosthesis were investigated using an astable multivibrator circuit, as changes in PVDF permittivity were observed according to variations of pressure and temperature. The results show that this prosthesis is reliable for use under different conditions of pressure (0 Pa to 16,350 Pa) and temperature (2 °C to 90 °C). The experimental results show an almost linear and inversely proportional behavior between the stimuli of pressure and temperature with the frequency response. This 3D-printed ear prosthesis is a promising tool and has a great potentiality in the biomedical engineering field because of its ability to generate an electrical potential proportional to pressure and temperature, and it is the first time that such a device has been processed by the additive manufacturing process (3D printing). More work needs to be carried out to improve the performance, such as electrical stimulation of the nervous system, thereby extending the purpose of a prosthesis to the area of sensory perception

Material Characterization of Thermoplastic Polyurethane (TPU) and Thermoplastic Elastomers (TPE) for Development of 3D-Printed Surrogate Organs for Medical Training

Cadaveric specimens are a necessary, albeit limited, resource for training medical students on basic surgical skills. The availability of surrogate 3D-printed organs would readily allow access to resources that could reduce or potentially eliminate the need for cadaveric specimens or, at a minimum, provide students the opportunity to practice with 3D-printed surrogates before transitioning to those specimens. This research focuses on determining which thermoplastic material most closely mimics mechanical properties such as hardness and stiffness of human organs and allows 3D printing surrogate organs to be used as safe, educational tools. Relatively “soft” materials such as thermoplastic polyurethanes (TPU) and thermoplastic elastomers (TPE) are selected as candidate materials for 3D printing of surrogate organs manufactured on a fusion deposition modeling printer (FDM). The mechanical properties of these materials are determined by a series of durometer, tensile, compression, puncture, cutting, and friction tests conducted for different printing configurations and testing conditions. Test results allowed the determination of the most suitable material for manufacturing the 3D-printed surrogate organs. This determination is based on data comparisons to unfixed and fixed cadaveric organs, porcine tissue, or through data reported in the literature. Professional anatomists and pathologists also tested a prototype model manufactured with the selected material to determine the level of realism and practicality of the 3D-printed prototype

A Fully 3D-printed Integrated Electrochemical Sensor System

This thesis investigates the design, fabrication, and characterization of a 3D printed electrochemical sensor as well as compact potentiostat circuits on Printed Circuit Board (PCB) for portable electrochemical sensing applications. Conductive 3D printing technologies are investigated as well as the advances in sensors and electronics applications. An optimized Directly Ink Writing (DIW) technique is adapted to a novel 3D-PCB fabrication platform using silver nanoparticle ink for electronics applications. An electrochemical device called potentiostat is designed based on an open source system. Its prototype is 3D printed on FR4 substrate. Using the same 3D platform, a lactate sensor which is composed of a 3-electrode is printed on the flexible substrate. Together, the 3D printed system demonstrates the electrochemistry test including cyclic voltammetry (CV) and amperometry. Results of this research demonstrate that 3D-PCB technology can significantly accelerate the fabrication process of conventional electronic, and merge its capability into electrochemical applications

Solvent Evaporation-Assisted Three-Dimensional Printing of Piezoelectric Sensors from Polyvinylidene Fluoride and its Nanocomposites

RÉSUMÉ Les matériaux piézoélectriques sont connus pour générer des charges électriques lors de leur déformation. Leur capacité à transformer linéairement l'énergie mécanique en énergie électrique, et vice versa, est utilisée dans la détection, l'actionnement, la récupération et le stockage d'énergie. Ces appareils trouvent des applications dans les domaines de l'aérospatiale, de la biomédecine, des systèmes micro-électromécaniques, de la robotique et des sports, pour n'en nommer que quelques-uns. On retrouve la propriété de piézoélectricité dans certaines céramiques, roches, monocristaux et quelques polymères. Le poly(fluorure de vinylidène) (PVDF) est un polymère piézoélectrique qui présente un coefficient piézoélectrique très élevé par rapport aux céramiques, ce qui laisse présager des applications de détection et de récupération d'énergie. La facilité de fabrication, la flexibilité et la biocompatibilité du PVDF sont autant de qualité qui en font un très bon candidat pour ces applications. Les dispositifs actuels à base de PVDF commercial sont disponibles en films plats ou en fibres unidimensionnelles (1D). L'impression tridimensionnelle (3D) du PVDF peut amener à des sensibilités, souplesses et capacités de fabrication accrues des capteurs embarqués en cas d'impression multi-matériaux. Le PVDF est un polymère semi-cristallin possédant cinq polymorphes, dont la phase β polaire qui présente les meilleures propriétés piézoélectriques. Malheureusement, le PVDF, provenant de la fusion ou de la dissolution, cristallise en une phase α non polaire thermodynamiquement stable. Diverses transformations physiques telles que le recuit, l'addition de charge, l'étirement ou le polissage sont effectuées pour transformer la phase α en phase β. En raison de la cristallisation inhérente du PVDF dans la phase α, il y a eu très peu de tentatives de fabrication de structures 3D à partir du PVDF. L'électrofilage en champ proche et la Déposition de Filament Fondu ont permis de fabriquer certaines structures 3D couche par couche avec du PVDF, soit avec l'application de hautes tensions électriques, soit avec la fusion à haute température du polymère. Et les deux nécessitent un traitement de polarisation pour conférer la piézoélectricité aux structures imprimés. Pour fabriquer des capteurs incorporés ou conformes, sur des substrats donnés, il est essentiel de ne pas avoir d'effets négatifs sur les matériaux adjacents à cause de la polarisation pendant le processus d'impression. Ainsi, dans ce travail, nous avons développé un procédé d'impression 3D qui crée des structures PVDF principalement en phase β, à température ambiante et sans application de tension de polarisation.----------ABSTRACT Piezoelectric materials are known to generate electric charges upon deformation. Their ability to linearly transform mechanical energy into electrical energy and vice versa, is utilized in sensing, actuation, transducing, energy harvesting and storage. These devices find applications in aerospace, biomedicine, micro electromechanical systems, robotics and sports, to name a few. Piezoelectricity is found in some ceramics, rocks, single crystals and a few polymers. Polyvinylidene fluoride (PVDF) is a piezoelectric polymer that exhibits a very high piezoelectric stress coefficient as compared to the ceramics, making it the forerunner for sensing and energy harvesting applications. PVDF’s formability, flexibility and biocompatibility, further reinforce its candidature. Present commercial PVDF-based devices come in flat films or one-dimensional (1D) fibers. Three-dimensional (3D) printing of PVDF leads to higher sensitivity, better compliance, and ability to print embedded sensors in case of multi-material printing. PVDF is a semi-crystalline polymer possessing five polymorphs, of which the polar β-phase exhibits highest piezoelectric properties. Unfortunately, PVDF from melt or solution crystallizes into a thermodynamically stable non-polar α-phase. Various physical transformations like annealing, filler addition, stretching or poling are carried out to transform the α-phase into β-phase. Due to the inherent crystallization of PVDF into α-phase, there have been very few attempts in fabricating 3D structures from PVDF. Near-field electrospinning and fused deposition modelling have demonstrated some layer-by-layer 3D structures with PVDF, either with application of high electric voltages or high temperature melting of the polymer, respectively. Also, both these techniques require a poling treatment to impart the desired piezoelectricity to the printed features. To fabricate embedded or conformal sensors on given substrates, it is essential to not have any adverse effects on the adjacent or substrate materials due to poling during the printing process. Thus, in this work, we develop a 3D printing process, that creates PVDF structures that inherently crystallize in the piezoelectric oriented β-phase at room temperature without any applied voltages. Solvent-evaporation assisted 3D printing is employed to print 3D piezoelectric structures of PVDF based solutions. In this process, the polymer solution is filled into a syringe which is inserted into a pneumatic dispenser. The pneumatic dispenser is mounted on a robotic arm that is controlled via a computer program