Projection-based stereolithography for direct 3D printing of heterogeneous ultrasound phantoms

Modern ultrasound (US) imaging is increasing its clinical impact, particularly with the introduction of US-based quantitative imaging biomarkers. Continued development and validation of such novel imaging approaches requires imaging phantoms that recapitulate the underlying anatomy and pathology of interest. However, current US phantom designs are generally too simplistic to emulate the structure and variability of the human body. Therefore, there is a need to create a platform that is capable of generating well-characterized phantoms that can mimic the basic anatomical, functional, and mechanical properties of native tissues and pathologies. Using a 3D-printing technique based on stereolithography, we fabricated US phantoms using soft materials in a single fabrication session, without the need for material casting or back-filling. With this technique, we induced variable levels of stable US backscatter in our printed materials in anatomically relevant 3D patterns. Additionally, we controlled phantom stiffness from 7 to >120 kPa at the voxel level to generate isotropic and anisotropic phantoms for elasticity imaging. Lastly, we demonstrated the fabrication of channels with diameters as small as 60 micrometers and with complex geometry (e.g., tortuosity) capable of supporting blood-mimicking fluid flow. Collectively, these results show that projection-based stereolithography allows for customizable fabrication of complex US phantoms.

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STRUCTURAL APPLICATION OF 3D PRINTING TECHNOLOGIES: MECHANICAL PROPERTIES OF PRINTED POLYMERIC MATERIALS / KONSTRUKCINIS 3D SPAUSDINIMO TECHNOLOGIJŲ TAIKYMAS: SPAUSDINTŲ POLIMERINIŲ MEDŽIAGŲ MECHANINĖS SAVYBĖS

Mokslas - Lietuvos ateitis ◽

10.3846/mla.2018.6250 ◽

2018 ◽

Vol 10 (0) ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Olena Shkundalova ◽

Arvydas Rimkus ◽

Viktor Gribniak

Keyword(s):

Mechanical Properties ◽

3D Printing ◽

Polymeric Materials ◽

Acrylonitrile Butadiene Styrene ◽

Tensile Tests ◽

Building Structures ◽

Printing Technique ◽

Printed Materials ◽

Printing Direction ◽

3D Printing Technique

Additive manufacturing and modern printing technologies using polymeric materials extend the limits of industrial production and encourage applying 3D printing technique in many fields. An item of any shape and size limited only by the printing pad of particular equipment can be reproduced from a variety of materials. Polymers is the object of this research. It is known that mechanical properties of the printed elements are closely related with the manufacturing technology and vary significantly depending on the chosen production parameters such as printing temperature, velocity, and infill density. Depending on the purpose, a particular type of polymer can be used in structural analysis. This work considers mechanical properties of four thermoplastic polymeric materials widely used for prototyping: polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), high impact polystyrene (HIPS), and polyethylene terephthalate (PETG). The study is focused on two fundamental mechanical characteristics, tensile strength and modulus of elasticity, of the printed material. Dumbbell-shaped samples were made of the PLA, ABS, HIPS and PETG polymers using 3D printing technique with the same filling density (≈ 20%) of the entry level. The tensile tests were carried out in Laboratory of Innovative Building Structures at Vilnius Gediminas Technical University. The predominant effect of the printing direction on the mechanical properties of the printed materials was demonstrated in this study. The corresponding experimental characteristics are presented in the manuscript. Santrauka Modernūs gamybos procesai ir spausdinimo technologijos, naudojant polimerines medžiagas, plečia pramoninės gamybos ribas bei skatina taikyti 3D spausdinimo technologijas daugelyje sričių. Tokios technologijos leidžia gaminti bet kokios formos elementus iš įvairių medžiagų, o jų dydį lemia tik naudojamos spausdinimo įrangos galimybės. Pagrindinis šio tyrimo objektas – polimerinės medžiagos. Spausdintų elementų iš polimerinių medžiagų mechaninės savybės glaudžiai siejamos su gamybos technologija ir gali stipriai varijuoti keičiant gamybos proceso parametrus – spausdinimo temperatūrą, greitį, užpildo tankį. Polimero tipas kartu su jo mechaninėmis savybėmis parenkamas atsižvelgiant į konstrukcinį uždavinį. Šiame darbe nagrinėjamos plačiai prototipų gamyboje taikomų termoplastinių polimerinių medžiagų – polietileno rūgšties (PLA), akrilonitrilo butadieno stireno (ABS), polistireno (HIPS) ir polietileno tereftalato (PETG) – mechaninės savybės. Tyrime dėmesys skiriamas dviem pagrindinėms mechaninėms medžiagų charakteristikoms – tempiamajam stipriui ir tamprumo moduliui. Taikant 3D spausdinimo technologiją buvo pagaminti kaulo formos bandiniai iš PLA, ABS, HIPS ir PETG medžiagų. Bandinių užpildo tankis siekė ≈ 20 % paviršiaus spausdinimo sluoksnio tankio. Elementų tempimo bandymai atlikti Inovatyvių statybinių konstrukcijų laboratorijoje Vilniaus Gedimino technikos universitete. Šiame tyrime buvo parodyta spausdinimo krypties įtaka spausdintų medžiagų mechaninėms savybėms. Taip pat pateiktos eksperimentiškai nustatytos polimerinių medžiagų mechaninės savybės.

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Untethered Hovering Flapping Flight of a 3D-Printed Mechanical Insect

Artificial Life ◽

10.1162/artl_a_00020 ◽

2011 ◽

Vol 17 (2) ◽

pp. 73-86 ◽

Cited By ~ 56

Author(s):

Charles Richter ◽

Hod Lipson

Keyword(s):

3D Printing ◽

Insect Flight ◽

Flapping Wing ◽

Wing Design ◽

Mechanical Parts ◽

Design Cycle ◽

3D Printed ◽

Printed Materials ◽

And Control ◽

3D Printing Technique

This project focuses on developing a flapping-wing hovering insect using 3D-printed wings and mechanical parts. The use of 3D printing technology has greatly expanded the possibilities for wing design, allowing wing shapes to replicate those of real insects or virtually any other shape. It has also reduced the time of a wing design cycle to a matter of minutes. An ornithopter with a mass of 3.89 g has been constructed using the 3D printing technique and has demonstrated an 85-s passively stable untethered hovering flight. This flight exhibits the functional utility of printed materials for flapping-wing experimentation and ornithopter construction and for understanding the mechanical principles underlying insect flight and control.

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Quantitative Imaging Biomarkers and their Emerging Role

Current Medical Imaging Formerly Current Medical Imaging Reviews ◽

10.2174/15734056113096660008 ◽

2013 ◽

Vol 9 (3) ◽

pp. 223-229

Author(s):

John Gore

Keyword(s):

Quantitative Imaging ◽

Imaging Biomarkers ◽

Quantitative Imaging Biomarkers

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Incorporating radiomics into clinical trials: expert consensus on considerations for data-driven compared to biologically driven quantitative biomarkers

European Radiology ◽

10.1007/s00330-020-07598-8 ◽

2021 ◽

Author(s):

Laure Fournier ◽

Lena Costaridou ◽

Luc Bidaut ◽

Nicolas Michoux ◽

Frederic E. Lecouvet ◽

...

Keyword(s):

Clinical Trials ◽

Quantitative Imaging ◽

A Priori ◽

External Validation ◽

Data Driven ◽

Imaging Biomarkers ◽

Clinical Validation ◽

Biological Processes ◽

Imaging Data ◽

Selection Of

Abstract Existing quantitative imaging biomarkers (QIBs) are associated with known biological tissue characteristics and follow a well-understood path of technical, biological and clinical validation before incorporation into clinical trials. In radiomics, novel data-driven processes extract numerous visually imperceptible statistical features from the imaging data with no a priori assumptions on their correlation with biological processes. The selection of relevant features (radiomic signature) and incorporation into clinical trials therefore requires additional considerations to ensure meaningful imaging endpoints. Also, the number of radiomic features tested means that power calculations would result in sample sizes impossible to achieve within clinical trials. This article examines how the process of standardising and validating data-driven imaging biomarkers differs from those based on biological associations. Radiomic signatures are best developed initially on datasets that represent diversity of acquisition protocols as well as diversity of disease and of normal findings, rather than within clinical trials with standardised and optimised protocols as this would risk the selection of radiomic features being linked to the imaging process rather than the pathology. Normalisation through discretisation and feature harmonisation are essential pre-processing steps. Biological correlation may be performed after the technical and clinical validity of a radiomic signature is established, but is not mandatory. Feature selection may be part of discovery within a radiomics-specific trial or represent exploratory endpoints within an established trial; a previously validated radiomic signature may even be used as a primary/secondary endpoint, particularly if associations are demonstrated with specific biological processes and pathways being targeted within clinical trials. Key Points • Data-driven processes like radiomics risk false discoveries due to high-dimensionality of the dataset compared to sample size, making adequate diversity of the data, cross-validation and external validation essential to mitigate the risks of spurious associations and overfitting. • Use of radiomic signatures within clinical trials requires multistep standardisation of image acquisition, image analysis and data mining processes. • Biological correlation may be established after clinical validation but is not mandatory.

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Complex Geometry Strain Sensors Based on 3D Printed Nanocomposites: Spring, Three-Column Device and Footstep-Sensing Platform

Nanomaterials ◽

10.3390/nano11051106 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1106

Author(s):

Alejandro Cortés ◽

Xoan F. Sánchez-Romate ◽

Alberto Jiménez-Suárez ◽

Mónica Campo ◽

Ali Esmaeili ◽

...

Keyword(s):

Carbon Nanotubes ◽

3D Printing ◽

Complex Geometry ◽

Uv Light ◽

Shielding Effect ◽

Strain Sensitivity ◽

Printing Technology ◽

3D Printing Technology ◽

Sensing Platform ◽

Electromechanical Performance

Electromechanical sensing devices, based on resins doped with carbon nanotubes, were developed by digital light processing (DLP) 3D printing technology in order to increase design freedom and identify new future and innovative applications. The analysis of electromechanical properties was carried out on specific sensors manufactured by DLP 3D printing technology with complex geometries: a spring, a three-column device and a footstep-sensing platform based on the three-column device. All of them show a great sensitivity of the measured electrical resistance to the applied load and high cyclic reproducibility, demonstrating their versatility and applicability to be implemented in numerous items in our daily lives or in industrial devices. Different types of carbon nanotubes—single-walled, double-walled and multi-walled CNTs (SWCNTs, DWCNTs, MWCNTs)—were used to evaluate the effect of their morphology on electrical and electromechanical performance. SWCNT- and DWCNT-doped nanocomposites presented a higher Tg compared with MWCNT-doped nanocomposites due to a lower UV light shielding effect. This phenomenon also justifies the decrease of nanocomposite Tg with the increase of CNT content in every case. The electromechanical analysis reveals that SWCNT- and DWCNT-doped nanocomposites show a higher electromechanical performance than nanocomposites doped with MWCNTs, with a slight increment of strain sensitivity in tensile conditions, but also a significant strain sensitivity gain at bending conditions.

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Gaining a better understanding of the extrusion process in fused filament fabrication 3D printing: a review

The International Journal of Advanced Manufacturing Technology ◽

10.1007/s00170-021-06918-6 ◽

2021 ◽

Author(s):

Bahaa Shaqour ◽

Mohammad Abuabiah ◽

Salameh Abdel-Fattah ◽

Adel Juaidi ◽

Ramez Abdallah ◽

...

Keyword(s):

3D Printing ◽

Numerical Models ◽

Extrusion Process ◽

Analytical Models ◽

Limiting Factor ◽

Fused Filament Fabrication ◽

Promising Tool ◽

Relevant Work ◽

3D Printing Technique ◽

Required Quality

AbstractAdditive manufacturing is a promising tool that has proved its value in various applications. Among its technologies, the fused filament fabrication 3D printing technique stands out with its potential to serve a wide variety of applications, ranging from simple educational purposes to industrial and medical applications. However, as many materials and composites can be utilized for this technique, the processability of these materials can be a limiting factor for producing products with the required quality and properties. Over the past few years, many researchers have attempted to better understand the melt extrusion process during 3D printing. Moreover, other research groups have focused on optimizing the process by adjusting the process parameters. These attempts were conducted using different methods, including proposing analytical models, establishing numerical models, or experimental techniques. This review highlights the most relevant work from recent years on fused filament fabrication 3D printing and discusses the future perspectives of this 3D printing technology.

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Importance of incorporating quantitative imaging biomarker technical performance characteristics when estimating treatment effects

Clinical Trials ◽

10.1177/1740774520981934 ◽

2021 ◽

pp. 174077452098193

Author(s):

Nancy A Obuchowski ◽

Erick M Remer ◽

Ken Sakaie ◽

Erika Schneider ◽

Robert J Fox ◽

...

Keyword(s):

Clinical Trials ◽

Confidence Intervals ◽

Treatment Effect ◽

Quantitative Imaging ◽

Imaging Biomarker ◽

Imaging Biomarkers ◽

Measurement Bias ◽

Technical Performance ◽

Quantitative Imaging Biomarker ◽

Performance Validation

Background/aims Quantitative imaging biomarkers have the potential to detect change in disease early and noninvasively, providing information about the diagnosis and prognosis of a patient, aiding in monitoring disease, and informing when therapy is effective. In clinical trials testing new therapies, there has been a tendency to ignore the variability and bias in quantitative imaging biomarker measurements. Unfortunately, this can lead to underpowered studies and incorrect estimates of the treatment effect. We illustrate the problem when non-constant measurement bias is ignored and show how treatment effect estimates can be corrected. Methods Monte Carlo simulation was used to assess the coverage of 95% confidence intervals for the treatment effect when non-constant bias is ignored versus when the bias is corrected for. Three examples are presented to illustrate the methods: doubling times of lung nodules, rates of change in brain atrophy in progressive multiple sclerosis clinical trials, and changes in proton-density fat fraction in trials for patients with nonalcoholic fatty liver disease. Results Incorrectly assuming that the measurement bias is constant leads to 95% confidence intervals for the treatment effect with reduced coverage (<95%); the coverage is especially reduced when the quantitative imaging biomarker measurements have good precision and/or there is a large treatment effect. Estimates of the measurement bias from technical performance validation studies can be used to correct the confidence intervals for the treatment effect. Conclusion Technical performance validation studies of quantitative imaging biomarkers are needed to supplement clinical trial data to provide unbiased estimates of the treatment effect.

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