Fabrication of 3d Mili-Scale Channels for Hemodynamic Studies

Abstract

3D mili-scale channel representing simplified anatomical models of blood vessels were constructed in polidimethylsiloxane (PDMS). The objective was to obtain a sequential method to fabricate transparent PDMS models from a mold produced by rapid prototyping. For this purpose, two types of casting methods were compared, a known lost-wax casting method and a casting method using sucrose. The channels fabricated by both casting methods were analyzed by Optical Microscopy, Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). The lost-wax method is not ideal since the channels become contaminated during the removal process. The models produced with the lost-sucrose casting method exhibit much better optical characteristics. These models are transparent with no visible contamination, since the removing process is done by dissolution at room temperature rather than melting. They allow for good optical access for flow visualization and measurement of the velocity field by micro-Particle Image Velocimetry (μPIV). The channels fabricated by the lost-sucrose casting method were shown to be suitable for future hemodynamic studies using optical techniques.

Geometrical effects in the hemodynamics of stenotic and non‐stenotic left coronary arteries—numerical and in vitro approaches

“…The fluid selected as blood analogue was a dimethyl sulfoxide (DMSO)/water mixture (52%/42%‐w/w), μ = 0.0035 Pa second and ρ = 1057.5 kg m −3 . This mixture eliminates the visual distortion given by the curvature of the phantoms walls by matching the refractive index of the PDMS . Although in small arteries and capillaries the blood exhibits non‐Newtonian behavior, in vessels of larger diameter, such as the coronary artery tree, the non‐Newtonian behavior is small because of the predominant high‐shear rates.…”

“…The 3D geometry designs were saved in STL format file for both numerical meshing and for constructing the experimental phantoms by rapid prototyping. The flow phantoms were prepared using a previously process developed by the authors . This method combines rapid prototyping (stereolithography) with sucrose molding and allows obtaining 3D poly (dimethylsiloxane) (PDMS) flow phantoms with any desired geometry.…”

“…The flow phantoms were prepared using a previously process developed by the authors. 28 This method combines rapid prototyping (stereolithography) with sucrose molding and allows obtaining 3D poly (dimethylsiloxane) (PDMS) flow phantoms with any desired geometry. PDMS is a widely used polymer in microfluidics and has a refractive index of approximately 1.4125 at 293 K. 29 In supporting information, Figure S2 illustrates this methodology by showing the fabrication steps of the LCA patient-specific flow phantom with and without stenosis.…”

“…This mixture eliminates the visual distortion given by the curvature of the phantoms walls by matching the refractive index of the PDMS. 28 Although in small arteries and capillaries the blood exhibits non-Newtonian behavior, in vessels of larger diameter, such as the coronary artery tree, the non-Newtonian behavior is small because of the predominant high-shear rates. For flow conditions similar to those in the present paper and in simplified models, Doutel et al 30 showed that the region of low WSS obtained assuming non-Newtonian behavior of the fluid is slightly smaller than the one obtained for Newtonian behavior.…”

3D manufacturing of intracranial aneurysm biomodels for flow visualizations: Low cost fabrication processes

“…Nevertheless, they face serious limitations for the case of hemodynamic studies. As visualizing the inner flow is imperative, they must be transparent to white light, its thickness should be less than the focal length of the objective used for experimental testing [17] and the used material must have a refractive index as closest as possible to the fluid one [18] .…”