Browsing by Author "Ferrera, Conrado"
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- 3D manufacturing of intracranial aneurysm biomodels for flow visualizations: low cost fabrication processesPublication . Souza, Andrews Victor Almeida; Souza, Mauren S.; Pinho, Diana; Agujetas, Rafael; Ferrera, Conrado; Lima, Rui A.; Puga, Hélder Fernandes; Ribeiro, J.E.There is a continuous search for better and more complete in vitro models with mechanical properties closer to in vivo conditions. In this work a manufacturing process, based on a lost core casting technique, is herein reported to produce aneurysm biomodels to perform experimental hemodynamic studies. By us- ing real artery images combined with a lost core casting technique, three materials were tested: paraffin, beeswax and glycerin-based soap. All in vitro biomodels were compared according to their transparency and final structure. Additionally, comparisons between experimental and numerical flow studies were also performed. The results have shown that the biomodels produced with beeswax and glycerine-based soap were the most suitable in vitro models to perform direct flow visualizations of particulate blood analogue fluids. The biomodels proposed in this works, have the potential to provide further insights into the complex blood flow phenomena happening at different kinds of pathologies and answer to important hemodynamics questions that otherwise cannot be tackled with the existing in vitro models.
- Additive manufacturing techniques for the fabrication of intracranial aneurysm biomodelsPublication . Rodrigues, D.; Souza, A.; Souza, Maria Sabrina; Ferrera, Conrado; Ribeiro, J.E.; Lima, Rui A.The hemodynamics of intracranial aneurysm (IA) involves complex phenomena that influence its growth and rupture. The advancement of additive manufacturing techniques allowed the development of biomodels suitable for in vitro experimental tests. Thus, we present in this work the process of manufacturing flow biomodels, using different additive manufacturing techniques and materials. The biomodels obtained through these methods proved to be suitable for experiments using imaging techniques and for the validation of numerical studies.
- Experimental and numerical analyses of the hemodynamics impact on real intracranial aneurysms: A particle tracking approachPublication . Souza, Andrews; Lopes, Diogo; Souza, Sérgio; Ribeiro, J.E.; Ferrera, Conrado; Lima, Rui A.This study investigates the impact of hemodynamics on real intracranial aneurysms (IAs) using experiments and computational fluid dynamics (CFD) simulations. A particle tracking velocimetry (PTV) approach was used to study the vortical structures inside a real aneurysm and validate numerical simulations performed at a steady regime for different flow rates. Moreover, this and two additional patient-specific cases have been numerically analyzed, focusing on flow patterns, wall shear stress (WSS), relative residence time (RRT), and oscillatory shear index (OSI) for transient studies. For the transient simulations, vorticity profiles indicated significant rotation of fluid particles in the neck and outlet arteries. TAWSS analysis revealed high WSS values in the bifurcation zone, neck, and middle cerebral artery (MCA), with variations among the patients. OSI and RRT plots provided insights into disturbed flow patterns, low or oscillatory WSS areas, and regions with prolonged residence time. This study shows great potential for combining PTV and CFD to obtain detailed insights into flow structures in aneurysms, which are crucial to developing effective treatments and interventions for IA management.
- Flow visualizations in a PDMS cerebral aneurysm biomodelPublication . Souza, Andrews Victor Almeida; Ferrera, Conrado; Puga, Hélder; Lima, Rui A.; Ribeiro, J.E.; Souza, Maria SabrinaCerebral aneurysm is an abnormal dilatation of the blood vessel which affects a high percentage of the worldwide population. One way to investigate this pathology is using in vivo techniques, but these types of experiments have a high cost and low reproducibility. Thus, to understand the local hemodynamics of brain aneurysms, it is imperative to manufacture in vitro models that simulate real brain aneurysms. These biomodels are suitable for experimental testing, as well as for evaluating and validating computational models. In this work, was manufactured a biomodel of a cerebral aneurysm made by polydimethylsiloxane (PDMS), combining rapid prototyping technology with a PDMS gravity casting process. Experimental flow visualizations were performed at different flow rates. The flow visualizations results have shown that there is a transition from laminar to turbulent flow for a flow rate near 6 ml/min. The proposed PDMS biomodels have shown the ability to perform flow visualizations and have the potential to help the development and validation of computational models.
- Recent Advances of PDMS In Vitro Biomodels for Flow Visualizations and Measurements: From Macro to Nanoscale ApplicationsPublication . Souza, Andrews; Nobrega, Glauco; Neves, Lucas Boniatti; Barbosa, Filipe; Ribeiro, J.E.; Ferrera, Conrado; Lima, Rui A.Polydimethylsiloxane (PDMS) has become a popular material in microfluidic and macroscale in vitro models due to its elastomeric properties and versatility. PDMS-based biomodels are widely used in blood flow studies, offering a platform for improving flow models and validating numerical simulations. This review highlights recent advances in bioflow studies conducted using both PDMS microfluidic devices and macroscale biomodels, particularly in replicating physiological environments. PDMS microchannels are used in studies of blood cell deformation under confined conditions, demonstrating the potential to distinguish between healthy and diseased cells. PDMS also plays a critical role in fabricating arterial models from real medical images, including pathological conditions such as aneurysms. Cutting-edge applications, such as nanofluid hemodynamic studies and nanoparticle drug delivery in organ-on-a-chip platforms, represent the latest developments in PDMS research. In addition to these applications, this review critically discusses PDMS properties, fabrication methods, and its expanding role in micro- and nanoscale flow studies.