3D-Printing mit der PolyJet-Technologie von Objet

Objet Geometries Ltd entwickelt und produziert Rapid Prototyping Systeme und Materialien auf Basis der Polyjet-Technologie und bietet diese im internationalen Markt an. Objet ist der „Pionier“ in der Entwicklung der Polyjet-Technologie zur schnellen Erstellung von hochwertigen Modellen aus den 3D-Daten der Design- und CAx-Systeme. Die Oberflächenqualität, die schnelle Reinigung des Supportmaterials mit Hilfe eines Wasserstrahls, die Bauteilqualität hinsichtlich der Genauigkeit sowie die einfache Bedienung der Systeme zu einem hervorragenden Preis/Leistungsverhältnis zeichnen Objet als Marktführer dieser Technologie aus. Die Systeme von Objet sind insbesondere für den Anwender in Design und Engineering konzipiert und können in einer Büroumgebung betrieben werden. Die verwendeten Materialien sind für den Anwender ohne jegliche Gefahr einsetzbar und sind von einem deutschen Institut mit entsprechenden Zertifikaten dokumentiert. Die Produktlinie von Objet ermöglicht im Design und Engineering die Zeiten in der Produktentwicklung erheblich zu reduzieren. Kunden von Objet sind in Nordamerika, Europa, Asien und Australien zu finden, viele von ihnen sind bedeutende Unternehmen aus den Märkten Automobilindustrie, Elektronik/Elektrotechnik, Spielwaren, Medizin, Konsumerprodukte, Schuhindustrie, Schmuckindustrie und vielen anderen Branchen. Objet wurde 1998 gegründet und befindet sich im privaten Besitz. Das Unternehmen wird von Investoren wie der Scitex Corporation sowie von weiteren privaten Investoren, Unternehmer-Kapitalfonden and Kooperationen in USA, Japan, Europa und Israel unterstützt. Aus Wettbewerbsgründen werden Unternehmenszahlen derzeit nicht öffentlich zur Verfügung gestellt. Das Unternehmen beschäftigt zur Zeit weltweit ca. 75 Mitarbeiter und verfügt über eigene Vertriebs- und Servicecenter in den USA und Europa, sowie Vertriebspartnern in der ganzen Welt. Seit Mitte 2001 wurden über 170 Systeme weltweit vermarktet und installiert. Der Vortrag anlässlich der RapidTech wird diese noch recht „junge“ Technologie, deren Vorteile für den Anwender sowie die möglichen Applikationen an Hand von konkreten Beispielen im Detail erläutern.

3D-Druck von Kunststoff-Medizinprodukten

Das Additive Manufacturing gewinnt im Bereich der Medizintechnik zur Herstellung von Prototypen bis hin zu Endprodukten zunehmend an Bedeutung. Ein großes Hemmnis stellen allerdings die relativ hohen Fertigungskosten dar. Hier bietet der verstärkte Einsatz der 3D-Drucktechnologie (3D Printing) ein erhebliches Potential zur Reduktion der Kosten. Aus dieser Motivation heraus wurde ein 3D-Druckverfahren zur Herstellung biokompatibler, sterilisierbarer Kunststoffmodelle entwickelt. Beim 3D-Druck-Verfahren handelt es sich um einen pulverbasierten Prozess zur schichtweisen Herstellung von Modellen direkt aus Computerdaten. Dabei werden dünne Schichten eines Pulvers auf eine Grundplatte aufgebracht, die dann durch gezielte Binderzugabe entsprechend des aktuellen Bauteilquerschnitts verfestigt werden. Ausgangsmaterial für diesen Prozess ist ein Granulatgemisch auf Basis von PMMA (Polymethylmethacrylat). Als Binderflüssigkeit wird ein Lösungsmittel eingesetzt. Die 3D gedruckten Modelle werden nach einer entsprechenden Trocknungszeit im Pulverbett entpackt und warmgelagert, um das Abdampfen des Lösungsmittels zu beschleunigen. Der Nachweis der Biokompatibilität der hergestellten Modelle erfolgte durch einen Test nach DIN EN ISO 10993-5. In Kooperation mit Anwendern wurden verschiedene Anwendungsbeispiele wie Bohrschablonen, Otoplastiken, Gebissmodelle und Modelle für die präoperative Planung realisiert und charakterisiert.

Design of a 3D printing capable of creating multiple objects simultaneously

Proyecto de Fin de Carrera de Ingenieria Industrial, versando sobre el completo diseño de una impresora 3D

The application of 3D printing to study microfluidic architecture for 'on-chip' mixing systems for SRCD and UV spectroscopy

This paper details methodologies that have been explored for the fast proofing of on-chip architectures for Circular Dichroism techniques. Flow-cell devices fabricated from UV transparent Quartz are used for these experiments. The complexity of flow-cell production typically results in lead times of six months from order to delivery. Only at that point can the on-chip architecture be tested empirically and any required modifications determined ready for the next six month iteration phase. By using the proposed 3D printing and PDMS moulding techniques for fast proofing on-chip architectures the optimum design can be determined within a matter of hours prior to commitment to quartz chip production.

Advanced Applications of 3D Dosimetry and 3D Printing in Radiation Therapy

As complex radiotherapy techniques become more readily-practiced, comprehensive 3D dosimetry is a growing necessity for advanced quality assurance. However, clinical implementation has been impeded by a wide variety of factors, including the expense of dedicated optical dosimeter readout tools, high operational costs, and the overall difficulty of use. To address these issues, a novel dry-tank optical CT scanner was designed for PRESAGE 3D dosimeter readout, relying on 3D printed components and omitting costly parts from preceding optical scanners. This work details the design, prototyping, and basic commissioning of the Duke Integrated-lens Optical Scanner (DIOS).

The convex scanning geometry was designed in ScanSim, an in-house Monte Carlo optical ray-tracing simulation. ScanSim parameters were used to build a 3D rendering of a convex ‘solid tank’ for optical-CT, which is capable of collimating a point light source into telecentric geometry without significant quantities of refractive-index matched fluid. The model was 3D printed, processed, and converted into a negative mold via rubber casting to produce a transparent polyurethane scanning tank. The DIOS was assembled with the solid tank, a 3W red LED light source, a computer-controlled rotation stage, and a 12-bit CCD camera. Initial optical phantom studies show negligible spatial inaccuracies in 2D projection images and 3D tomographic reconstructions. A PRESAGE 3D dose measurement for a 4-field box treatment plan from Eclipse shows 95% of voxels passing gamma analysis at 3%/3mm criteria. Gamma analysis between tomographic images of the same dosimeter in the DIOS and DLOS systems show 93.1% agreement at 5%/1mm criteria. From this initial study, the DIOS has demonstrated promise as an economically-viable optical-CT scanner. However, further improvements will be necessary to fully develop this system into an accurate and reliable tool for advanced QA.

Pre-clinical animal studies are used as a conventional means of translational research, as a midpoint between in-vitro cell studies and clinical implementation. However, modern small animal radiotherapy platforms are primitive in comparison with conventional linear accelerators. This work also investigates a series of 3D printed tools to expand the treatment capabilities of the X-RAD 225Cx orthovoltage irradiator, and applies them to a feasibility study of hippocampal avoidance in rodent whole-brain radiotherapy.

As an alternative material to lead, a novel 3D-printable tungsten-composite ABS plastic, GMASS, was tested to create precisely-shaped blocks. Film studies show virtually all primary radiation at 225 kVp can be attenuated by GMASS blocks of 0.5cm thickness. A state-of-the-art software, BlockGen, was used to create custom hippocampus-shaped blocks from medical image data, for any possible axial treatment field arrangement. A custom 3D printed bite block was developed to immobilize and position a supine rat for optimal hippocampal conformity. An immobilized rat CT with digitally-inserted blocks was imported into the SmART-Plan Monte-Carlo simulation software to determine the optimal beam arrangement. Protocols with 4 and 7 equally-spaced fields were considered as viable treatment options, featuring improved hippocampal conformity and whole-brain coverage when compared to prior lateral-opposed protocols. Custom rodent-morphic PRESAGE dosimeters were developed to accurately reflect these treatment scenarios, and a 3D dosimetry study was performed to confirm the SmART-Plan simulations. Measured doses indicate significant hippocampal sparing and moderate whole-brain coverage.

3D nanoimprint technology for NIR Fabry-Pérot filter arrays

Im Rahmen dieser Arbeit wird die Herstellung von miniaturisierten NIR-Spektrometern auf Basis von Fabry-Pérot (FP) Filter Arrays behandelt. Bisher ist die kostengünstige Strukturierung von homogenen und vertikal erweiterten Kavitäten für NIR FP-Filter mittels Nanoimprint Technologie noch nicht verfügbar, weil die Qualität der Schichten des Prägematerials unzureichend ist und die geringe Mobilität der Prägematerialien nicht ausreicht, um die vertikal erweiterten Kavitäten zu füllen. Diese Arbeit konzentriert sich auf die Reduzierung des technischen Aufwands zur Herstellung von homogenen und vertikal erweiterten Kavitäten. Zur Strukturierung der Kavitäten wird ein großflächiger substratkonformer UV-Nanoimprint Prozess (SCIL - Substrate Conformal Imprint Lithoghaphy) verwendet, der auf einem Hybridstempel basiert und Vorteile von harten und weichen Stempeln vereint. Um die genannten Limitierungen zu beseitigen, werden alternative Designs der Kavitäten untersucht und ein neues Prägematerial eingesetzt. Drei Designlösungen zur Herstellung von homogenen und erweiterten Kavitäten werden untersucht und verglichen: (i) Das Aufbringen des Prägematerials mittel mehrfacher Rotationsbeschichtung, um eine höhere Schichtdicke des Prägematerials vor dem Prägeprozess zu erzeugen, (ii) die Verwendung einer hybriden Kavität bestehend aus einer strukturierten Schicht des Prägematerials eingebettet zwischen zwei Siliziumoxidschichten, um die Schichtdicke der organischen Kavität zu erweitern und (iii) die Optimierung des Prägeprozesses durch Verwendung eines neuen Prägematerials. Die mit diesen drei Ansätzen hergestellten FP-Filter Arrays zeigen, hohe Transmissionen (beste Transmission > 90%) und kleine Linienbreiten (Halbwertsbreiten <5 nm).

3D Printing and bioprinting of osteomimetic materials for 3D in vitro models and tissue repair applications

Bone disorders have severe impact on body functions and quality life, and no satisfying therapies exist yet. The current models for bone disease study are scarcely predictive and the options existing for therapy fail for complex systems. To mimic and/or restore bone, 3D printing/bioprinting allows the creation of 3D structures with different materials compositions, properties, and designs. In this study, 3D printing/bioprinting has been explored for (i) 3D in vitro tumor models and (ii) regenerative medicine. Tumor models have been developed by investigating different bioinks (i.e., alginate, modified gelatin) enriched by hydroxyapatite nanoparticles to increase printing fidelity and increase biomimicry level, thus mimicking the organic and inorganic phase of bone. High Saos-2 cell viability was obtained, and the promotion of spheroids clusters as occurring in vivo was observed. To develop new syntethic bone grafts, two approaches have been explored. In the first, novel magnesium-phosphate scaffolds have been investigated by extrusion-based 3D printing for spinal fusion. 3D printing process and parameters have been optimized to obtain custom-shaped structures, with competent mechanical properties. The 3D printed structures have been combined to alginate porous structures created by a novel ice-templating technique, to be loaded by antibiotic drug to address infection prevention. Promising results in terms of planktonic growth inhibition was obtained. In the second strategy, marine waste precursors have been considered for the conversion in biogenic HA by using a mild-wet conversion method with different parameters. The HA/carbonate ratio conversion efficacy was analysed for each precursor (by FTIR and SEM), and the best conditions were combined to alginate to develop a composite structure. The composite paste was successfully employed in custom-modified 3D printer for the obtainment of 3D printed stable scaffolds. In conclusion, the osteomimetic materials developed in this study for bone models and synthetic grafts are promising in bone field.

High precision anatomy for MEG.

Precise MEG estimates of neuronal current flow are undermined by uncertain knowledge of the head location with respect to the MEG sensors. This is either due to head movements within the scanning session or systematic errors in co-registration to anatomy. Here we show how such errors can be minimized using subject-specific head-casts produced using 3D printing technology. The casts fit the scalp of the subject internally and the inside of the MEG dewar externally, reducing within session and between session head movements. Systematic errors in matching to MRI coordinate system are also reduced through the use of MRI-visible fiducial markers placed on the same cast. Bootstrap estimates of absolute co-registration error were of the order of 1mm. Estimates of relative co-registration error were <1.5mm between sessions. We corroborated these scalp based estimates by looking at the MEG data recorded over a 6month period. We found that the between session sensor variability of the subject's evoked response was of the order of the within session noise, showing no appreciable noise due to between-session movement. Simulations suggest that the between-session sensor level amplitude SNR improved by a factor of 5 over conventional strategies. We show that at this level of coregistration accuracy there is strong evidence for anatomical models based on the individual rather than canonical anatomy; but that this advantage disappears for errors of greater than 5mm. This work paves the way for source reconstruction methods which can exploit very high SNR signals and accurate anatomical models; and also significantly increases the sensitivity of longitudinal studies with MEG.

Construção de escalas de silhuetas brasileiras para crianças entre quatro e seis anos de idade

O objetivo principal deste trabalho foi desenvolver duas escalas de silhuetas para crianças de ambos os sexos entre quatro e seis anos de idade, para avaliação da percepção e insatisfação com o tamanho corporal. O estudo foi composto por duas etapas. A primeira etapa envolveu a construção de uma escala de silhuetas bidimensional e uma escala de silhuetas tridimensional, a partir das fotos de 18 crianças voluntárias, divididas em nove crianças de cada sexo, sendo uma representante para cada intervalo de IMC estabelecido para a construção das escalas. Para garantir as qualidades psicométricas dos instrumentos, estabeleceram-se os valores médios de IMC correspondentes para cada figura com incremento constante de 1,9 Kg/m². Foram fotografadas crianças com Índice de Massa Corporal correspondente às médias dos intervalos estabelecidos para as figuras da sequência das escalas. Estas fotos foram transformadas por um designer gráfico em um arquivo para impressão 3D e um arquivo 2D frontal de silhuetas infantis. A segunda etapa contemplou a análise das qualidades psicométricas dos instrumentos. A coleta de dados ocorreu em quatro escolas particulares em diferentes cidades. Participaram do estudo 193 crianças de quatro a seis anos de idade, sendo 102 do sexo feminino e 91 do sexo masculino. As escalas foram apresentadas para cada criança em ordem ascendente ou aleatória, perguntando-se Qual figura representa seu corpo atual? e Qual figura representa o corpo que você gostaria de ter?, sendo a discrepância entre a figura que representa o IMC Atual e a que representa o IMC Desejado, caracterizada como Insatisfação com o tamanho corporal, e a discrepância entre a figura que representa o IMC Real e a que representa o IMC Atual caracterizada como Inacurácia da percepção do tamanho corporal. A escala bidimensional é apresentada na forma de nove cartões plastificados para cada gênero, com 12,5cm de altura por 6,5cm de largura, com a figura centralizada. A escala tridimensional é composta de nove bonecos para cada gênero impressos através da tecnologia de impressão 3D, com 12cm de altura. A Escala de Silhuetas Bidimensional mostrou valores de fidedignidade satisfatórios para Acurácia e Satisfação para crianças de seis anos, podendo ser um indicativo da influência do ambiente e do desenvolvimento em crianças menores. A Escala de Silhuetas Tridimensional apresentou-se mais adequada para a avaliação da Insatisfação com o tamanho corporal em relação a Bidimensional, mostrando que detalhes mais reais permitem um melhor julgamento por parte das crianças, seja do corpo como um todo, seja de partes dele. Este estudo sugere que as escalas de silhuetas podem ser usadas em crianças, e que pré-escolares já conseguem cumprir a tarefa de selecionar a figura que representa seu corpo nesta faixa etária. A construção e desenvolvimento das escalas mostraram-se ser válidas e permitem a investigação mais acurada de fatores relacionados as dimensões perceptivas da imagem corporal em pré-escolares, porém, parecem refletir também outras fontes de variância e influência que precisam ser investigadas.

Caraterização e modelação do comportamento mecânico da resina fotopolimerizada V-Flash FTI-GN

A utilização de tecnologias de prototipagem em objetos e estruturas do dia-a-dia é cada vez maior. Porém, os componentes que é possível fabricar estão em geral associados a protótipos demonstrativos não funcionais. Para ultrapassar estas limitações têm vindo a ser desenvolvidos novos materiais, procurando a melhoria das suas características mecânicas. A presente dissertação insere-se no projeto Firend®, que se tem vindo a desenvolver numa parceria entre a Academia Militar e outras instituições como o Instituto Superior Técnico e procura avaliar a viabilidade da utilização da técnica de deposição de resina fotopolimerizável por ultra-violeta no fabrico de projéteis para o transporte especial de agentes extintores, procurando caracterizar o desempenho deste material em condições operativas simulativas do disparo real. A pesquisa bibliográfica da presente dissertação baseou-se numa breve introdução aos materiais poliméricos. O trabalho teórico consistiu na modelação numérica através do método dos elementos finitos do ensaio de compressão utilizando o programa Deform® e na respetiva validação do modelo através de comparação dos resultados das simulações com dados experimentais existentes na literatura da especialidade. O trabalho experimental fundamentou-se no fabrico e preparação de provetes através da tecnologia de impressão 3D, na descrição das ferramentas utilizadas e do plano experimental. No final verificou-se a fratura de todos os provetes ensaiados e uma grande dispersão dos resultados, conseguindo-se apenas retirar uma tensão de segurança que não deve ser ultrapassada. De acordo com o estudo realizado o material ensaiado demonstrou-se não ser apropriado para a aplicação pretendida e recomenda-se a avaliação de outros materiais igualmente utilizados pelas técnicas de prototipagem rápida, tais como uma mistura de uma resina polimérica com um outro material com características mecânicas mais adequadas.

Additive Manufacturing: Current Status and Future Prospects

Part 10: Sustainability and Trust

Développement d’un dispositif d’extrusion tridimensionnelle de sucre vitrifié pour la production de réseaux fluidiques complexes par moulage rapide

L’objectif du vaste projet de recherche dans lequel s’inscrit ce mémoire est de guérir le diabète de type 1 en fabriquant un pancréas bioartificiel vascularisé contenant des cellules bêta (i.e. les cellules sécrétant l’insuline). Ce dispositif permettrait de rendre aux personnes atteintes par le diabète de type 1 la capacité de sécréter par elles-mêmes de l’insuline et de réguler leur glycémie. La vascularisation est actuellement un enjeu de taille dans le domaine du génie tissulaire. La plupart des tissus incorporant des cellules générées par le génie tissulaire sont actuellement fortement limités en épaisseur faute d’être vascularisés adéquatement. Pour les tissus dont l’épaisseur dépasse 400 μm, la vascularisation est nécessaire à la survie de la plupart des cellules qui autrement souffriraient d’hypoxie, les empêchant ainsi d’accomplir leurs fonctions [1]. Ce mémoire présente le développement et la mise en service d’un dispositif d’extrusion tridimensionnelle de sucre vitrifié pour la vascularisation d’un pancréas bioartificiel. Ce dispositif a été développé au laboratoire de recherche sur les procédés d’impression 3D ainsi qu’au bureau de design du département de génie mécanique de l’Université Laval. Grâce à cette technique d’impression 3D novatrice et à la caractérisation du procédé, il est maintenant possible de produire rapidement et avec précision des structures temporaires en sucre vitrifié pour la fabrication de réseaux vasculaires tridimensionnels complexes. Les structures temporaires peuvent, après leur production, être utilisées pour réaliser le moulage rapide de constructions vascularisées avec des matériaux tels que du polydiméthylsiloxane (PDMS) ou des hydrogels chargés de cellules biologiques. De par la nature du matériel utilisé, les moules temporaires peuvent être facilement et rapidement dissous dans une solution aqueuse et laisser place à un réseau de canaux creux sans créer de rejets toxiques, ce qui représente un avantage majeur dans un contexte de bio-ingénierie.

Radiation characteristics enhancement of planar structures using metasurfaces

In this thesis, the focus is on utilizing metasurfaces to improve radiation characteristics of planar structures. The study encompasses various aspects of metasurface applications, including enhancing antenna radiation characteristics and manipulating electromagnetic (EM) waves, such as polarization conversion and anomalous reflection. The thesis introduces the design of a single-port antenna with dual-mode operation, integrating metasurfaces. This antenna serves as the front-end for a next-generation tag, functioning as a position sensor with identification and energy harvesting capabilities. It operates in the lower European Ultra-Wideband (UWB) frequency range for communication/localization and the UHF band for wireless energy reception. The design aims for a low-profile stack-up that remains unaffected by background materials. Researchers worldwide are drawn to metasurfaces due to their EM wave manipulation capabilities. The thesis also demonstrates how a High-Impedance Surface (HIS) can enhance the antenna's versatility through metasurface application, including conformal design using 3D-printing technology, ensuring adaptability for various deformation and tracking/powering scenarios. Additionally, the thesis explores two distinct metasurface applications. One involves designing an angularly stable super-wideband Circular Polarization Converter (CPC) operating from 11 to 35GHz with an impressive relative impedance bandwidth of 104.3%. The CPC shows a stable response even at oblique incidences up to 40 degrees, with a Peak Cross-Polarization Ratio (PCR) exceeding 62% across the entire band. The second application focuses on an Intelligent Reflective Surface (IRS) capable of redirecting incoming waves in unconventional directions. Tunability is achieved through an artificially developed ferroelectric material (HfZrO) and distributed capacitive elements (IDC) to fine-tune impedance and phase responses at the meta-atom level. The IRS demonstrates anomalous reflection for normal incident waves. These innovative applications of metasurfaces offer promising advancements in antenna design, EM wave manipulation, and versatile wireless communication systems.