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3T3 Cells, Animals, Biomechanical Phenomena, Cell Movement drug effects, Cell Proliferation drug effects, Ink, Mice, Microscopy, Electron, Scanning, Porosity, Printing, Fibroins pharmacology, Tissue Scaffolds, and Tomography, Optical Coherence

To date, naturally derived biomaterials are rarely used in advanced tissue engineering (TE) methods despite their superior biocompatibility. This is because these native materials, which consist mainly of proteins and polysaccharides, do not possess the ability to withstand harsh processing conditions. Unlike synthetic polymers, natural materials degrade and decompose rapidly in the presence of chemical solvents and high temperature, respectively. Thus, the fabrication of tissue scaffolds using natural biomaterials is often carried out using conventional techniques, where the efficiency in mass transport of nutrients and removal of waste products within the construct is compromised. The present study identified silk fibroin (SF) protein as a suitable material for the application of rapid prototyping (RP) or additive manufacturing (AM) technology. Using the indirect RP method, via the use of a mould, SF tissue scaffolds with both macro- and micro-morphological features can be produced and qualitatively examined by spectral-domain optical coherence tomography (SD-OCT). The advanced imaging technique showed the ability to differentiate the cells and SF material by producing high contrasting images, therefore suggesting the method as a feasible alternative to the histological analysis of cell growth within tissue scaffolds.
(Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.)

Adult, Bone Transplantation methods, Humans, Image Processing, Computer-Assisted, Male, Models, Theoretical, Prosthesis Design, Software, Tomography, X-Ray Computed, Biocompatible Materials, Mandible chemistry, Mandibular Prosthesis, Mandibular Prosthesis Implantation methods, Materials Testing, and Titanium chemistry

Unlabelled: During the past few years, the combination of medical imaging and rapid manufacturing technique has proven to be a very important development. On the other hand, the conventional method has some drawbacks. For example, it takes longer time to complete an operation and it also presents some difficulty in matching the repaired contours. With advanced software and hardware, an image of an undamaged bone similar to that of the patient can be made from computerised tomography (CT); and a physical object constructed by the mirror-processed image data can be quickly fabricated with a high degree of fitting with the patient's bone. This paper presents a methodology for the design and fabrication of an individual titanium tray for the repair of mandible defects. Methods for the tray modeling using CAD system are presented: A 3D model of the bony defect is generated after the acquisition of helical CT data. An individual tray is designed using freeform surfaces geometries and fabricated by rapid prototyping (RP) technology. The results of tray filling with bone-grafting materials are then presented.
Result: the tray is inserted into the patient mandible segment. The symmetry and reconstruction quality contour of the repaired mandible was satisfactory. Thus, the patient is able to eat normally. The bone-grafting material harvested from the anterior ilium was low. The clinical experience showed that rapid prototyping and reverse engineering software are effective methods of fabricating custom trays for mandibular reconstruction after bone loss due to a tumor.

Algorithms, Biomechanical Phenomena, Porosity, Shear Strength, Biocompatible Materials chemistry, Computer-Aided Design, Tissue Engineering methods, and Tissue Scaffolds chemistry

Advanced additive techniques are now being developed to fabricate scaffolds with controlled architecture for tissue engineering. These techniques combine computer-aided design (CAD) with computer-aided manufacturing (CAM) tools to produce three-dimensional structures layer by layer in a multitude of materials. Actual prediction of the effective mechanical properties of scaffolds produced by additive technologies, is very important for tissue engineering applications. A novel computer based technique for scaffold design is topological optimisation. Topological optimisation is a form of "shape" optimisation, usually referred to as "layout" optimisation. The goal of topological optimisation is to find the best use of material for a body that is subjected to either a single load or a multiple load distribution. This paper proposes a topological optimisation scheme in order to obtain the ideal topological architectures of scaffolds, maximising its mechanical behaviour.
(2010 IPEM. Published by Elsevier Ltd. All rights reserved.)

Adult, Biomedical Engineering instrumentation, Biomedical Engineering methods, Cephalometry instrumentation, Cephalometry methods, Craniosynostoses pathology, Evaluation Studies as Topic, Femur anatomy histology, Hip Prosthesis, Humans, Image Processing, Computer-Assisted instrumentation, Infant, Magnetic Resonance Imaging methods, Tomography, X-Ray Computed methods, Image Processing, Computer-Assisted methods, Lasers, and Models, Anatomic

Rapid prototyping techniques, originally developed for building components from computer aided designs in the motor industry, are now being applied in medicine to build models of human anatomy from high resolution multiplanar imaging data such a computed tomography (CT). The established technique of stereolithography and the more recent selective laser sintering (SLS), both build up an object layer by layer. Models have applications in surgical planning, for the design of customised implants and for training. Preliminary experience of using the SLS technique for medical applications is described, addressing questions regarding image processing, data transfer and manufacture. Pilot models, built from nylon, included two skills (a child with craniosynoslosis and an adult with hypertetorism) and a normal femur which was modelled for use in a bioengineering test of an artificial hip. The dimensions of the models were found to be in good agreement with the CT data from which they were built-for the child's skull the difference between the model and the CT data was less than 1.0 +/- 0.5 mm in each direction. Our experience showed that, with care, a combination of existing software packages may be used for data conversion. Ideally, image data of high spatial resolution should be used. The pilot models generated sufficient clinical interest for the technique to be pursued in the orthopaedic field.

Rapid prototyping or 'virtual prototyping' of human-machine interfaces offers the possibility of putting the human operator 'in the loop' without the effort and cost associated with conventional man-in-the-loop simulation. Advocates suggest that rapid prototyping is compatible with conventional systems development techniques. It is not clear, however, exactly how rapid prototyping could be used in relation to conventional human factors engineering analyses. Therefore, an investigation of the use of the VAPS virtual prototyping system was carried out in five organizations. The results show that a variety of task analysis approaches can be used to initiate rapid prototyping. Overall, it appears that rapid prototyping facilitates an iterative approach to the development of the human-machine interface, and that is most applicable to the early stages of systems development, rather than to detailed design.

Compressive Strength, Computer Simulation, Elasticity, Finite Element Analysis, Models, Biological, Stress, Mechanical, Tomography, X-Ray Computed, and Bone and Bones diagnostic imaging

A new experimental validation method for assessing the accuracy of large-scale finite element (FE) models of bone micro-structure at the apparent and tissue level was developed. Augmented scaled bone replicas were built using rapid prototype machines based on micro-computed tomography (micro-CT) data. The geometric accuracy of the model was evaluated by comparing experimental tests with the replicas to the FE solution based on the same micro-CT data. A new version of the large-scale FE solver was developed to incorporate orthotropic material properties, hence the experimentally determined properties of the rapid prototype material were input into the FE models. The modified FE solver predicted the experimental apparent level stiffness within less than 1%, and the difference between experimental strain gauge measurements and FE-calculated surface stresses was 7% and 49% on a flat and curved surface region, respectively. While absolute error estimates of surface stresses were limited due to strain gauge errors, the relatively larger difference on the curved surface is indicative of the limitations of a hexahedron FE model for representing such geometries. Although the validation approach is applied here for hexahedron based meshes, the method is flexible for varying bone architectures and will be important for validation of future large-scale FE modeling developments that utilize techniques such as mesh smoothing and tetrahedron elements.

The aim of this study was to evaluate and improve the menu interface design of an existing expert system. The system provided expertise concerned with evaluating human response to environments and was implemented onto a computer with a simple tree menu system. Two laboratory based experiments were carried out in which alternative menu interface designs were developed rapidly and compared with the original design. User acceptance tests which incorporated objective and subjective measures were iteratively used to evaluate and improve the interface designs. The results of these experiments indicated that, for the particular system under study, a graphic based design which displayed 58 options divided into levels on a single screen was preferred by users over the original menu interface which displayed one menu at a time with seven options per screen. The final interface remains to be tested under field conditions.

Objective: To identify requirements for human-in-the-loop simulation capabilities and improve their utility in predicting and optimizing soldier-systems integration.
Background: Technological development rates within the military are rapidly increasing. Emergent technologies often exclude in-depth consideration of human-system interactions until the physical prototyping phase. Human-in-the-loop simulation tools can allow for earlier consideration of humans in the development process; however, use remains limited.
Method: Semi-structured interviews were conducted with key informants to yield perspectives on current human-in-the-loop simulation capabilities and utility specific to the military. An inductive approach to thematic analysis was used to extract critical themes from transcribed interview data. A scoping review was completed to supplement the data obtained from interviews and summarize knowledge regarding requirements for human-in-the-loop simulation and analysis capabilities targeted to the military.
Results: Interviews were conducted with five experts representing the sectors of Vehicle/Equipment Design, Simulation, and Army Research. A total of 2274 sources were identified, and 64 papers were retained for the scoping review. Thematic analysis of the combined data sources yielded six important themes to consider with respect to requirements for future human-in-the-loop simulation capabilities targeting soldier-systems integration.
Conclusion: This study has identified eight key requirements to support the use of human-in-the-loop simulation tools to predict and optimize soldier-systems integration and performance.
Application: Addressing key requirements will improve the ability of current human-in-the-loop simulation tools to accommodate the military's need for human consideration early in the design process.
(Copyright © 2020 Elsevier Ltd. All rights reserved.)

Mechanical Phenomena, Solubility, Water chemistry, Aorta, Precision Medicine instrumentation, Printing, Three-Dimensional, Prosthesis Design methods, and Stents

Endovascular aneurysm repair (EVAR) is a popular and effective treatment for descending aortic disease. However, the majority of existing coating stents used in EVAR are of a standard design which may not meet the size or structural requirements of different patients. Therefore, in this paper, we propose using 3D printing and controlled deposition as a patient-specific aortic stent graft manufacturing technique. The methodology involves the use of a rapid prototyping study sacrificial core-coating forming (RPSC-CF) technique to develop an aortic stent graft that consists of a film and metallic stent. Polyether polyurethane and nickel-titanium alloys were chosen due to their shape memory properties and good biocompatibility. The resulting customized stent grafts meet the demands of personalized therapy and invasive surgery, and perform well as demonstrated from burst pressure testing and the degree of radial support provided and radial support force tests, laying the foundation for precise aortic dissection treatment.
(Copyright © 2019. Published by Elsevier Ltd.)

Adult, Female, Humans, Male, Proof of Concept Study, User-Computer Interface, Virtual Reality, Young Adult, Computer Terminals, Ergonomics methods, Research Design, and Smart Glasses

Mixed prototyping, combining virtual and physical prototypes, is an emerging method used to aid in usability testing. This study aims to determine when to use a mixed prototype and how to choose its fidelity to validate the usability testing results and reduce the prototyping cost. A 2×2 between-subject experiment was designed to investigate the effects of the media (head-mounted display versus computer monitor) and physical interaction (using a tangible mock-up or not) on the usability evaluation results and other subjective measures. The experiment results showed that, when aesthetic and functional features are controlled, the non-functional mock-up facilitates users in finding problems regarding physical interaction and ergonomics. Media with high immersion positively influenced the users' subjective ratings. Based on the findings of this study, guidelines on how to choose the fidelity of the prototype during different stages of a usability test are suggested to help product developers find a cost-efficient way to conduct usability tests.
(Copyright © 2019 Elsevier Ltd. All rights reserved.)

Adult, Humans, Maintenance, Male, Middle Aged, User-Computer Interface, Equipment Design, Ergonomics methods, and Extraction and Processing Industry instrumentation

In recent years, the use of virtual prototyping has increased in product development processes, especially in the assessment of complex systems targeted at end-users. The purpose of this study was to evaluate the suitability of virtual prototyping to support human factors/ergonomics evaluation (HFE) during the design phase. Two different virtual prototypes were used: augmented reality (AR) and virtual environment (VE) prototypes of a maintenance platform of a rock crushing machine. Nineteen designers and other stakeholders were asked to assess the suitability of the prototype for HFE evaluation. Results indicate that the system model characteristics and user interface affect the experienced suitability. The VE system was valued as being more suitable to support the assessment of visibility, reach, and the use of tools than the AR system. The findings of this study can be used as a guidance for the implementing virtual prototypes in the product development process.
(Copyright © 2016 Elsevier Ltd. All rights reserved.)

Compliance, Materials Testing, Silicones, Aorta anatomy histology, Computer-Aided Design, and Models, Anatomic

We design and manufacture a silicone model of the human aorta, able to mimic both the geometrical and the mechanical properties of physiological individuals, with a specific focus on reproducing the compliance. In fact, while the models available in the literature exhibit an unrealistic compliant behavior, though they are detailed from the geometrical viewpoint, here the goal is to provide an accurate compliant tool for in vitro testing the devices that interface with the vascular system. A parametric design of the aortic model is obtained based on the available literature data, and the model is manufactured with a specific silicone mixture using rapid prototyping and molding techniques. The manufactured prototype has been tested by means of computed tomography scans for evaluating the matching of the mechanical properties with the desired ones. Results show a high degree of adherence between the imposed and the measured compliance values for each main aortic section. Thus, our work proves the feasibility of the approach, and the possibility to manufacture compliant models that reproduce the mechanical behavior of the aorta for in vitro studies.
(Copyright © 2018 IPEM. Published by Elsevier Ltd. All rights reserved.)

Disabled Persons rehabilitation, Engineering trends, Humans, Self-Help Devices, Engineering methods, and Rehabilitation instrumentation

Over the past four decades, there have been breakthroughs in communication, mobility and tools to manipulate objects. Probably the most important transformation has been the growing inclusion of people with disabilities into the prioritization, conceptualization, and design of new assistive devices. Advances in technology, demands from people with disabilities, and changes in cultural perceptions have made noteworthy changes in the technologies that have improved lives, and affected transformations that benefit both individuals and society. People with disabilities lives have been improved but there is still much to be done. Unfortunately, people with disabilities in low income countries have lagged people in higher income countries in benefitting from technical and social changes. Assistive devices have benefitted from the availability of powerful, portable computing power, from small low-power sensors, from new materials, from rapid prototyping and flexible manufacturing. There are exciting emerging technologies that show promise for future advances.
(Copyright © 2019. Published by Elsevier Ltd.)

Beverages, Consumer Behavior, Female, Healthy Volunteers, Humans, Male, Snacks, Spine, Students psychology, Young Adult, Back Pain psychology, Commerce instrumentation, Equipment Design psychology, Man-Machine Systems, and Posture

Currently, the word 'comfort' is often used in relation to the marketing of products such as chairs, cars interiors, clothing, hand tools and even airplane tickets. In this field of research, the aim of this study is to investigate the influence of spinal posture on postural (dis)comfort perception; the test case is the analysis of the interaction between humans and vending machines for purchasing food or beverages. A statistical sample of 20 healthy students (subjects) performed the required tests, with each participant asked to take a product from three different vending machines (snacks, drinks and coffee). The subjects' postures were acquired non-invasively using cameras; software and instruments for virtual prototyping were used for posture analysis and interaction modelling, both questionnaires (subjective) and comfort-analysis software (objective) were used to rate the perceived (dis)comfort. The results obtained from simulations and questionnaires were compared, and a method to weigh the effect of the perceived spinal discomfort on overall postural (dis)comfort was proposed. These results reveal a good correlation between subjective perception and objective evaluation obtained through simulations, confirming the validity of the proposed method.
(Copyright © 2018 Elsevier Ltd. All rights reserved.)

Axilla, Female, Humans, Lymph Nodes, Musculoskeletal Pain etiology, Prone Position, Tomography, X-Ray Computed, Torso diagnostic imaging, Breast Neoplasms radiotherapy, Equipment Design adverse effects, Musculoskeletal Pain prevention control, Patient Comfort, Patient Positioning, and Radiotherapy instrumentation

Although many authors stated that a user-centred design approach in medical device development has added values, the most common research approach within healthcare is evidence-based medicine, which tend to focus on functional data rather than patient wellbeing and comfort. End user comfort is well addressed in literature for commercial products such as seats and hand tools but no data was found for medical devices. A commercial patient support device for breast radiotherapy was analysed and a relation was found between discomfort and uncompensated internal body forces. Derived from CT-images, simplified patient free-body diagrams were analysed and pain and comfort evaluated. Subsequently, a new patient position was established and prototypes were developed. Patient comfort- and prototype optimization was done through iterative prototyping. With this approach, we were able to compensate all internal body forces and establish a force neutral patient free-body diagram. This resulted in comfortable patient positioning and favourable medical results.
(Copyright © 2018 Elsevier Ltd. All rights reserved.)

Humans, Research Design, Cone-Beam Computed Tomography, Image Processing, Computer-Assisted, and Models, Anatomic

This paper presents a method of improving the accuracy of the tridimensional reconstruction of human bone biomodels by means of tomography, with a view to finite element modelling or surgical planning, and the subsequent manufacturing using rapid prototyping technologies. It is focused on the analysis and correction of the results obtained by means of cone beam computed tomography (CBCT), which is used to digitalize non-superficial biological parts along with a gauge part with calibrated dimensions. A correction of both the threshold and the voxel size in the tomographic images and the final reconstruction is proposed. Finally, a comparison between a reconstruction of a gauge part using the proposed method and the reconstruction of that same gauge part using a standard method is shown. The increase in accuracy in the biomodel allows an improvement in medical applications based on image diagnosis, more accurate results in computational modelling, and improvements in surgical planning in situations in which the required accuracy directly affects the procedure's results. Thus, the subsequent constructed biomodel will be affected mainly by dimensional errors due to the additive manufacturing technology utilized, not because of the 3D reconstruction or the image acquisition technology.
(Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.)

Adult, Femoral Artery diagnostic imaging, Humans, Male, Tomography, X-Ray Computed, Femoral Artery physiology, Finite Element Analysis, Models, Biological, and Pulsatile Flow

The model-based, rapid-prototyping-enabled design and manufacture of a pulsatile blood vessel (PBV) for high-fidelity mannequin-based clinical simulations is presented. The PBV presented here is a pressurized, flexible tube with alternating fluid pressure created by a pump to mimic the behavior of a human vessel in response to pulsatile pressure. The use of PBVs is important for the fidelity of a clinical simulator that requires residents to palpate and/or access the vessel. In this study, a PBV is presented which features the integration of 3D modeling using patient-specific computed tomography (CT) data, mold fabrication using rapid-prototyping, and finite element method for estimating the required pumping pressure to generate the same level of force (about 1.5 N) experienced by the user through palpation. The relationship between this palpation force and the vessel pressure is studied using two strategies: finite element analysis (FEA) and experiments in a femoral arterial access simulator with a pump, artificial vessel, and surrounding phantom tissue. The experimental results show a discrepancy of 8.7% from the FEA-predicted value. Qualitative validation is done by exposing and surveying 19 interventional cardiology residents at four major educational institutions to the simulator for accuracy of its feel. The overall survey results are positive.
(Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.)

Humans, Tomography, X-Ray Computed, Bone and Bones diagnostic imaging, Imaging, Three-Dimensional methods, and Machine Learning

An effective method for reconstructing a 3D model of human bones from computed tomography (CT) image data based on dictionary learning is proposed. In this study, the dictionary comprises the vertices of triangular meshes, and the sparse coefficient matrix indicates the connectivity information. For better reconstruction performance, we proposed a balance coefficient between the approximation and regularisation terms and a method for optimisation. Moreover, we applied a local updating strategy and a mesh-optimisation method to update the dictionary and the sparse matrix, respectively. The two updating steps are iterated alternately until the objective function converges. Thus, a reconstructed mesh could be obtained with high accuracy and regularisation. The experimental results show that the proposed method has the potential to obtain high precision and high-quality triangular meshes for rapid prototyping, medical diagnosis, and tissue engineering.
(Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.)

Adult, Female, Humans, Male, Middle Aged, Equipment Design standards, Ergonomics methods, Manufacturing Industry instrumentation, and Task Performance and Analysis

We present an application of engineering and ergonomics principles in the design of a standardised tool, The Dibber, which is a tool with multiple geometric features to fit the diversity of lay-up tasks used in the composites industry. The Dibber is the result of a design process, which consists of a series of observations and prototyping to extract geometric requirements for lay-up tasks. To demonstrate that it is possible to design a standardised tool prototypes of the Dibber were distributed and 91 participants gave feedback. Our results are positive and show consistent patterns of use across industry sectors, as well as between novice and expert laminators.
(Copyright © 2017. Published by Elsevier Ltd.)