Experimental Flow Studies in PDMS Intracranial Aneurysms

Manufactured by Two Different Techniques

Andrews Souza

1,2,3 a

, Inês Afonso

1,3 b

, Violeta Carvalho

1,2,4,5 c

, Diana F. Rodrigues

Senhorinha Teixeira

, João Eduardo Ribeiro

, José Eduardo Socha Pereira

Reinaldo Rodrigues de Souza

1,6 g

, Rui Lima

1,7 h

and Ana Sofia Moita

MEtRICs, Mechanical Engineering Department, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal

Center for MicroElectromechanical Systems (CMEMS-UMinho), University of Minho,

Campus de Azurém, 4800-058 Guimarães, Portugal

Campus de Santa Apolónia, CIMO—Instituto Politécncio de Bragança, 5300-253 Bragança, Portugal

ALGORITMI/LASI Center, University of Minho, Campus de Azurém, 4800‐058 Guimarães, Portugal

LABBELS—Associate Laboratory, Braga/Guimarães, Portugal

IN+, Center for Innovation, Technology and Policy Research, Instituto Superior Técnico, Universidade de Lisboa,

Av. Rovisco Pais, 1049-001, Lisboa, Portugal

CEFT, Faculdade de Engenharia da Universidade do Porto (FEUP), Rua Roberto Frias, 4200-465, Porto, Portugal

ALiCE - Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto,

Rua Dr. Roberto Frias, 4200-465 Porto, Portugal

st@dps.uminho.pt, jribeiro@ipb.pt, sochapereira@tecnico.ulisboa.pt, reinaldo.souza@tecnico.ulisboa.pt,

rl@dem.uminho.pt, anamoita@tecnico.ulisboa.pt

Keywords: Intracranial Aneurism Biomodels, PDMS, In vitro Flow Test, Biofluids, Additive Manufacturing, Polysmooth.

Abstract: The aim of this study was to investigate the flow within intracranial aneurysms, which are localized dilations

of the cerebral arteries that pose a risk of rupture and strokes. The experimental analysis was conducted on

scaled-down biomodels of a cerebral aneurysm to better understand its flow patterns. To carry out the

experimental phase, the biomodels were manufactured using rapid prototyping and lost core casting

techniques. The biomodels were assessed for optical transparency and dimensions, confirming their suitability

for flow visualization tests. The findings revealed that within the recirculation zones of the aneurysm, the

flow velocities were notably lower when compared to the entry and exit points. As the flow rate increased,

the recirculation focus gradually approached the aneurysm wall. Furthermore, the geometry of the aneurysm

played an important role in influencing the flow behavior. These insights are crucial, as they are linked to

some extent with the risk of intracranial aneurysm rupture, which may entail severe consequences. This study

enriches our understanding of the aneurysm flow dynamics and contributes to the development of the inherent

preventative and treatment measures.

1 INTRODUCTION

Intracranial aneurysms are localized dilations of the

arteries in the brain (Rodriguez-Régent et al., 2014).

https://orcid.org/0000-0003-2414-073X

https://orcid.org/0000-0001-6416-2867

https://orcid.org/0000-0002-9447-4746

https://orcid.org/0000-0002-7464-3944

https://orcid.org/0000-0001-6300-148X

https://orcid.org/0000-0001-7244-8611

https://orcid.org/0000-0001-5250-820X

https://orcid.org/0000-0003-3428-637X

https://orcid.org/0000-0001-9801-7617

These dilations can weaken the blood vessel wall and

increase the risk of rupture, becoming a significant

cause of cerebrovascular accidents. They usually

develop in the major arteries of the cerebral

152

Souza, A., Afonso, I., Carvalho, V., Rodrigues, D., Teixeira, S., Ribeiro, J., Pereira, J., Rodrigues de Souza, R., Lima, R. and Moita, A.

Experimental Flow Studies in PDMS Intracranial Aneurysms Manufactured by Two Different Techniques.

DOI: 10.5220/0012417600003657

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 17th International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC 2024) - Volume 1, pages 152-158

ISBN: 978-989-758-688-0; ISSN: 2184-4305

circulation, particularly in specific locations within

the so-called "Willis polygon" (Lasheras, 2007).

Some studies have identified that the anterior cerebral

artery is involved in around 40% of cases of

intracranial aneurysm rupture (Inagawa 2010; Ye et

al. 2017).

These aneurysms can be classified into two main

groups based on their geometry and location:

fusiform and saccular, with saccular aneurysms being

the most common type, representing approximately

90% of cases (Lasheras 2007). Blood flow within

aneurysms depends on various factors, including the

size, shape of the aneurysm, and the geometry of the

originating artery (Ye et al. 2017).

To study these aneurysms, there are experimental

and numerical approaches. Experimental approaches

typically involve creating in vitro models that

simulate blood flow and artery deformation. Studies

show that the initial models were made of glass

(Ferguson, 1972), and later, silicone models emerged

(Steiger et al. 1988). Currently, they have been

produced using PDMS (Souza et al., 2020). In this

regard, various techniques have been applied to these

models, such as Magnetic Resonance, Doppler Laser,

Digital Image Correlation, PTV (Particle Tracking

Velocimetry), and PIV (Particle Image Velocimetry)

(Steiger et al. 1988; Roloff et al. 2013; Souza,

2020b). It should be noted that the most used

experimental technique to validate numerical

simulations is the PIV technique.

Manufacturing technology has evolved, using

materials like PDMS (polydimethylsiloxane) to

create aneurysm models. PDMS is chosen due to its

hyper elasticity, biocompatibility, and cost-

effectiveness (Miranda, 2022).

The manufacturing and subsequent experimental

studies of representative biomodels of a cerebral

aneurysm, with mechanical properties close to those

of arteries, are of utmost importance to understand the

phenomena responsible for the growth and rupture of

intracranial aneurysms (Souza et al., 2020; Rodrigues

et al. 2016). Therefore, the current work has the

primary objective of studying the blood flow in a

representative biomodel of a cerebral aneurysm,

specifically focusing on the fabrication of semi-rigid

optimized biomodels suitable for experimental flow

visualization.

In this regard, and considering the manufacturing

processes studied, IA (Intracranial Aneurism)

biomodels were manufactured. The first biomodel

was made using a manufacturing process described in

more detailed at Souza et al., 2020. Briefly, the

manufacture of the aneurysm lumen involves a

combination of additive manufacturing methods and

a lost core casting process using glycerin-based soap.

The second one was manufactured using the FDM

(Fused Deposition Modelling) technique and the

material used was polysmooth. This material allows

surface treatment with isopropyl alcohol to smooth

out the roughness from the printing process. At the

end of both processes, the lumens obtained are

positioned in an acrylic box where the PDMS were

casted by gravity and cured for 48 hours at room

temperature. The results of this work have shown that

the biomodels of beeswax and glycerine-based soap

were the most suitable in vitro models to perform

direct flow visualizations of particulate blood

analogue fluids. The authors proposed an effective

manufacturing method from real flow biomodels, at

the millimeter scale and suitable for hemodynamic

studies.

2 MATERIALS AND METHODS

2.1 Experimental Setup

For the experimental flow visualization tests, a set

interconnected equipment was essential. Two key

components worth mentioning include the high-speed

video device, which primarily featured a Photron

FASTCAM high-speed camera, complemented by

visualization software for post-processing and

analysis. In addition, an inverted microscope model

IX71 from Olympus™ was also used, together with a

N-Achroplan 2.5x/0.07 objective. Figure 1 illustrates

the primary equipment employed in this study,

including the high-speed camera, inverted

microscope, syringe pump, PDMS biomodel, and

acquisition system.

Figure 1: Schematic representation of the experimental

setup.

Experimental Flow Studies in PDMS Intracranial Aneurysms Manufactured by Two Different Techniques

153

2.2 Evaluation of the Optical

Transparency of the Biomodel

When studying biomodels, certain limitations must

be considered. One of these restrictions pertains to

optical properties, specifically the requirement that

the material used for the external biomodel must be

transparent, and its refractive index should closely

match that of the fluid used in experiments. This

alignment of refractive indexes is crucial to facilitate

experimental flow visualization tests on the PDMS

biomodels.

In cases where there is a significant disparity

between the refractive index of the fluid and that of

the PDMS, distortions may appear near the walls.

However, this distortion can be mitigated or

eliminated when the refractive index of the fluid

closely matches that of the biomodel material (Souza

et al., 2020).

It is important to bear this update issue in mind, as

it may subsequently have a negative influence on the

visualization of particles when carrying out the

experimental tests.

Thus, in the present study, with the aim of

evaluating the optical transparency of the biomodel,

two fluids with different physical properties were

considered, so that it was possible to make a

comparison and perceive the differences between

them. Therefore, one of the used fluids, which has a

refractive index very similar to that of PDMS, was a

mixture of liquid glycerin and distilled water, that is,

61 grams of liquid glycerin were diluted in distilled

water (61% w/w). The second used fluid was only

water.

It is important to mention that the application of

this technique, to evaluate the optical transparency of

the biomodel under study, was based on the work of

Hopkins et al., 2000.

The physical properties of the materials used in

the present study are summarized in Table 1:

Physical properties of the employed materials to

evaluate the optical transparency of biomodels..

It should be noted that these properties were

considered as explained in (Souza et al., 2020).

Table 1: Physical properties of the employed materials to

evaluate the optical transparency of biomodels.

Material Refractive

Index

Viscosity

(Pa. s)

Density

)

Wate

1.333 9.20 x10

-4

997

Glycerin

mixture

1.412 1.29 x10

-2

1153

PDMS 1.412 -

2.3 Flow Visualization Experimental

Testing

In the initial step, the PDMS biomodel was secured

under the microscope. Subsequently, a syringe pump

system, utilizing a Terumo™ 50 mL syringe, was

employed to deliver the working fluid at a fixed flow

rate. This fluid was pumped not only through the

channels connecting the syringe to the biomodel but

also within the biomodel itself.

The fluid used in this flow visualization

experiment was a mixture of liquid glycerin and 61%

distilled water (w/w). Additionally, 0.06% PMMA

(polymethylmethacrylate) particles with a 60 μm

diameter were suspended in this fluid. It's worth

noting that the selection of this fluid was based on

previous work conducted by Campo-Deaño et al.

(2013) and Pinho et al. (2017). Table 1 presents the

physical properties of the fluid under investigation,

including density, refractive index, and viscosity with

the suspended particles.

The primary objectives of this experimental test

were to evaluate, depending on the considered flow

rates, the occurrence of fluid recirculation, observed

by tracking particle trajectories. Additionally, the

study aimed to measure velocities in different zones

of the biomodel. It's important to mention that the in-

vitro study was conducted exclusively on the two

biomodels produced using additive manufacturing

molds.

For the case of the biomodel in which the inlet and

outlet channels have an angle of 180° between them,

six different flow rates were evaluated, i.e., 5 mL/min

(⇒ Re (Reynolds Number)=1.95), 6.8 mL/min (⇒

Re=2.65), 10 mL/min (⇒ Re=3.90), 20 mL/min (⇒

Re=7.80), 50 mL/min (⇒ Re =19.49) and still 100

mL/min (⇒ Re=38.99).

In turn, for the case of the biomodel in which the

inlet and outlet channels have an angle of 60° to each

other, only the flow rates of 8 mL/min (⇒ Re=3.12),

15 mL/min (⇒ Re=5.85), 30 mL/min (⇒ Re=11.70)

and 50 mL/min (⇒ Re=19.49) were inferred. It is

noteworthy to refer that, for this second biomodel, the

study started with a flow rate of 8 mL/min, because

during the experimental test, this was the flow rate

from which the phenomenon of recirculation began to

be verified.

2.4 Evaluation of the Geometric

Structure of the Molds and

Biomodels

One of the requirements regarding the manufacture of

biomodels is that their geometries must correspond to

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the original STL (Standard Tessellation Language)

model. In this sense, and with the aim of verifying this

issue, images were acquired, both of the biomodels

and of the aneurysms (molds) that originated the

biomodels, using the inverted microscope used in the

experimental tests. It should be emphasized that both

the aneurysms and the biomodels measured were only

those that showed a 50% reduction. Once the images

were obtained, there were carried out measurements

in the different locations, using the ImageJ software.

It's important to note that dimensions were

evaluated for all three biomodels produced and

studied in this work. This includes the two biomodels

with polysmooth lost nuclei (featuring different

geometries) and the biomodel with the glycerin-based

soap core, although no experimental tests were

conducted on the latter.

The dimensions of both the resin aneurysm and

the polysmooth aneurysms with different geometries

were assessed. It's worth highlighting that for the

polysmooth aneurysms, measurements were taken

both before and after the application of the superficial

treatment.

To evaluate the geometric structure,

measurements were taken at three specific locations.

These measurements were conducted around the

aneurysm and in each of its arms, as illustrated in

Figure 2.

Figure 2: Schematic representation of the locations of the

biomodel in which there were taken measurements to

evaluate the geometric structure.

3 RESULTS

3.1 Results for the Evaluation of the

Optical Transparency of the

Biomodel

For the experimental work, a sheet with a rectangular

structure was used in which each black or white

rectangles had 2.4 x 3.9 mm of dimensions and under

which the biomodel was placed. Thus, this structure

aimed to allow the evaluation of the issue of optical

distortion, caused by solid-liquid interaction.

Figure 3 presents the results for the biomodel

using a polysmooth mold. Image (a) shows the

biomodel when water was injected, while image (b)

depicts the situation in with a glycerin-based solution.

(a) (b)

Figure 3: Evaluation of the optical transparency of the

biomodel. In this evaluation, the inlet and outlet channels

have a 180° angle to each other, and a glycerin-based soap

mold was used. Panel (a) represents the case with water as

the fluid, while panel (b) shows the case with a glycerin-

based solution.

(a) (b)

Figure 4: Evaluation of the optical transparency of the

biomodel, in which the inlet and outlet channels have an

angle of 180° to each other, and where the mold used

consisted of polysmooth, for the situation in which the fluid

used was water (a) and for the case where the fluid was a

glycerin-based solution (b).

To begin with, Figure 4 displays the results

obtained for the biomodel using a glycerin-based soap

mold. Image (a) corresponds to the biomodel with

water injection, and image (b) depicts the situation

with a glycerin-based solution.

One can see that, when water is used as the

injected fluid (with a lower refractive index than

PDMS), the mold walls are visible. In contrast, when

a glycerin-based solution is used (with a matching

refractive index to PDMS), the mold walls become

invisible.

Additionally, it is worth noting that when water is

used, there is some slight distortion and curvature of

the rectangle structure, which is visible in all three

biomodels. This effect is more pronounced in the case

of the biomodel using a glycerin-based soap mold (as

shown in Figure 3).

3.2 Qualitative Analysis of Flow

Behaviour

The recorded images, using the Photron FASTCAM

visualization software, were subsequently processed

Experimental Flow Studies in PDMS Intracranial Aneurysms Manufactured by Two Different Techniques

155

using the ImageJ software. In particular, the particle

trajectories were obtained using the Z Project plugin,

and velocities using the MTrackJ plugin.

Firstly, the case of the biomodel in which the inlet

and outlet channels have an angle of 180° between

them. Thus, the trajectories of the PMMA particles,

for a flow rate of 5 mL/min, 6.8 mL/min and 10

mL/min, resulting from the image processing, are

shown in Figure 5.

(a) (b) (c)

Figure 5: Trajectories of the PMMA particles, for a flow

rate of 5 mL/min (Re=1.95), (a); 6.8 mL/min (Re=2.65), (b)

and 10 mL/min (Re=3.90), (c). The arrow inserted in each

image translates the direction of fluid circulation.

From observation of the previous figure, one can

see that for a flow rate of 5 mL/min, (a), the

phenomenon of fluid recirculation has not yet

occurred.

In turn, for a flow rate of 6.8 mL/min, (b), the

respective phenomenon is already beginning to be

observed, although it is still reduced and only occurs

in an area located inside the aneurysm. It should also

be noted that this recirculation zone occurs on the

fluid inlet side. On the other hand, for a flow rate of

10 mL/min, (c), it is visible that the recirculation

phenomenon is already perfectly developed and

covers almost the entire interior of the aneurysm.

(a) (b) (c)

Figure 6: PMMA particle trajectories, for a flow rate of 20

mL/min (Re=7.80), (a4); 50 mL/min (Re=19.49), (a5) and

100 mL/min (Re=38.99), (a6). The arrow introduced in

each image reflects the direction of fluid circulation.

After studying the trajectories of the PMMA

particles for the three flow rates discussed previously,

we now proceeded to study the flow rates of 20

mL/min, 50 mL/min and 100mL/min. Therefore, the

particle trajectories for the aforementioned flow rates,

and resulting from image processing, are shown in

Figure 6.

By analyzing the previous figure, it is possible to

observe that as the flow rate increases, the intensity

of recirculation also increases. Additionally, it is

noteworthy that the region of the aneurysm occupied

by the recirculation phenomenon expands with the

higher flow rates. For example, in the case of flow

rates of 50 mL/min (b) and 100 mL/min (c), virtually

all aneurysms exhibit recirculation. Furthermore, it is

evident that with the increase in flow rate, the

recirculation focus moves closer and closer to the

aneurysm wall.

3.3 Results of the Geometric

Assessment of Molds and

Biomodels

Firstly, the dimensions of the mold which originated

the final biomodel, in PDMS were evaluated. Two

measurements were taken at each location and,

subsequently, the average was calculated.

After obtaining the average values, these were

then compared with the dimensions of the original

STL model. This comparison was made by

calculating the relative percentage error between

both.

Therefore, in the following Table 2, there is a

comparison made between the measurements

obtained in ImageJ and the dimensions of the model

in the STL file, for the resin mold.

Table 2: Comparison between the measurements obtained

in ImageJ and the dimensions of the model in the STL file,

by calculating the relative percentage error, for the resin

mold.

Name Length-

ImageJ

(mm)

Length-

Inventor

(mm)

Relative

Error (%)

Aneurysm 4.934 5.00 1.33%

Left Arm 1.883 1.85 1.78%

Right Arm 1.809 1.85 2.22%

Analyzing the percentage errors obtained for the

resin mold, it is possible to verify the existence of

reduced errors in the order of 2%. The small value of

these errors ends up proving, in a certain way, the

good surface finish of the parts obtained by the

MSLA (Masked Stereo Lithography Apparatus)

additive manufacturing technique.

In a second phase, the dimensions of the final

biomodel in PDMS was evaluated.

This means that there were also taken two

dimensions at each location of the studied biomodel

and, subsequently, these values were averaged. After

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obtaining the average values, it was then compared

with the dimensions of the original STL model. Once

again, this comparison was made by calculating the

relative percentage error between both.

Thus, Table 3 shows a comparison made between

the measurements obtained in the ImageJ software

and the dimensions of the model in the STL file, for

the biomodel in which the lost nucleus was made of

glycerin-based soap.

Table 3: Comparison between the measurements obtained

in the ImageJ software and the dimensions of the STL file

model, by calculating the percentage error, for the PDMS

biomodel (in which the missing nucleus was made of

glycerin-based soap).

Name Length-

ImageJ

(mm)

Length-

Inventor

(mm)

Relative

Error (%)

Aneurysm 5.204 5.00 4.07%

Left Arm 1.946 1.85 5.20%

Right Arm 1.885 1.85 1.86%

4 CONCLUSIONS

The main objective of this study was to investigate

the flow in an idealized semi-rigid biomodel

representing an intracranial aneurysm. The flow

visualization tests identified areas within the

aneurysm where fluid recirculation occurred.

Notably, the central region of the aneurysm, where

recirculation occurred, exhibited lower velocities

compared to the inlet and outlet speeds. With an

increase in the flow rate, the disparity between the

velocity inside the aneurysm and the inlet and outlet

velocities became more pronounced, indicating an

expanded recirculation area within the aneurysm.

Furthermore, an increase in the flow rate resulted in

the recirculation focus moving closer to the aneurysm

wall. It is highly recommended to conduct further

studies concerning the aim of this paper, namely there

should be performed numerical analysis for

validating the experimental results for the two studied

geometries. It is suggested to conduct numeric

simulations in steady state and transient regime to

infer if there are discrepancies between the velocity

values determined experimentally and numerically.

Apart from the validation of results, further numeric

simulations will produce a more profitable use of the

velocity and pressure profiles in terms of the

prediction of aneurism geometries that are at high risk

of rupture.

ACKNOWLEDGEMENTS

Authors acknowledge the projects

EXPL/EME-EME/0732/2021, 2022.06207.PTDC

(https://doi.org/10.54499/2022.06207.PTDC) and

2022.03151.PTDC (https://doi.org/10.54499/2022.

03151.PTDC) for the financial support, through

national funds (OE), within the scope of the Scientific

Research and Technological Development Projects

(IC&DT) program in all scientific domains (PTDC),

PORTUGAL 2020 Partnership Agreement, European

Regional Development Fund (FEDER), via the

Foundation for Science and Technology, I.P.

(FCT, I.P) and the R&D Units projects

(UIDB/00690/2020 and UIDP/00690/2020) (CIMO),

SusTEC (LA/P/0007/2020), UIDB/04077/2020,

UIDP/04077/2020, UIDB/04436/2020,

UIDB/00532/2020, LA/P/0045/2020 (ALiCE). and

LA/P/0083/2020 IN + - IST-ID. Andrews Souza

acknowledges FCT for the Ph.D. scholarship

2021.07961.BD and José Pereira acknowledges FCT

for the Ph.D. scholarship Ref. 2021.05830.BD.

REFERENCES

Campo-Deaño, L.; Dullens, R.; Aarts, D.; Pinho, F.;

Oliveira, M. (2013). Viscoelasticity of Blood and

Viscoelastic Blood Analogues for Use in

Polydymethylsiloxane in Vitro Models of the

Circulatory System. Biomicrofluidics, 7, 34102,

doi:10.1063/1.4804649.

Ferguson G. G. (1972). Physical factors in the initiation,

growth, and rupture of human intracranial saccular

aneurysms. Journal of neurosurgery, 37(6), 666–677.

https://doi.org/10.3171/jns.1972.37.6.0666.

Hopkins, L.M.; Kelly, J.T.; Wexler, A.S.; Prasad, A.K.

(2000). Particle Image Velocimetry Measurements in

Complex Geometries. Exp. Fluids, 29, 91–95,

doi:10.1007/s003480050430.

Inagawa T. (2010). Site of ruptured intracranial saccular

aneurysms in patients in Izumo City, Japan.

Cerebrovascular diseases (Basel, Switzerland), 30(1),

72–84. https://doi.org/10.1159/000314623.

Lasheras, J.C. (2006). The Biomechanics of Arterial

Aneurysms. Annu. Rev. Fluid Mech., 39, 293–319,

doi:10.1146/annurev.fluid.39.050905.110128.

Pinho, D.; Campo-Deaño, L.; Lima, R.; Pinho, F.T. (2017)

In Vitro Particulate Analogue Fluids for Experimental

Studies of Rheological and Hemorheological Behavior

of Glucose-Rich RBC Suspensions. Biomicrofluidics,

11, doi:10.1063/1.4998190.

Rodrigues, R.O.; Pinho, D.; Bento, D.; Lima, R.; Ribeiro,

J. (2016). Wall Expansion Assessment of an

Intracranial Aneurysm Model by a 3D Digital Image

Correlation System. Measurement, 88, 262–270,

Experimental Flow Studies in PDMS Intracranial Aneurysms Manufactured by Two Different Techniques

157

doi:https://doi.org/10.1016/j.measurement.2016.03.04

Rodriguez-Régent, C.; Edjlali-Goujon, M.; Trystram, D.;

Boulouis, G.; Ben Hassen, W.; Godon-Hardy, S.; Nataf,

F.; Machet, A.; Legrand, L.; Ladoux, A.; et al. (2014)

Non-Invasive Diagnosis of Intracranial Aneurysms.

Diagn. Interv. Imaging, 95, 1163–1174,

doi:https://doi.org/10.1016/j.diii.2014.10.005.

Roloff, C.; Bordás, R.; Nickl, R.; Mátrai, Z.; Szaszák, N.;

Szilárd, S.; Thévenin, D. (2013). Investigation of the

Velocity Field in a Full-Scale Model of a Cerebral

Aneurysm. Int. J. Heat Fluid Flow, 43, 212–219,

doi:https://doi.org/10.1016/j.ijheatfluidflow.2013.06.0

06.

Miranda, I.; Souza, A.; Sousa, P.; Ribeiro, J.; Castanheira,

E.M.S.; Lima, R.; Minas, G. (2022). Properties and

Applications of PDMS for Biomedical Engineering: A

Review"Journal of Functional Biomaterials 13, 1: 2.

doi: https://doi.org/10.3390/jfb13010002

Souza, A.; Souza, M.S.; Pinho, D.; Agujetas, R.; Ferrera,

C.; Lima, R.; Puga, H.; Ribeiro, J. (2020) 3D

Manufacturing of Intracranial Aneurysm Biomodels for

Flow Visualizations: Low Cost Fabrication Processes.

Mech. Res. Commun., 107, 103535, doi:10.1016/

j.mechrescom.2020.103535.

Souza, A. V. A. (2020b). Hemodynamic study in a real

intracranial aneurysm: an in vitro and in silico

approach,” Dissertação de Mestrado, Instituto

Politécnico de Bragança, Bragança/Portugal.

Steiger, H.J.; Liepsch, D.W.; Poll, A.; Reulen, H.J. (1988).

Hemodynamic Stress in Terminal Saccular Aneurysms:

A Laser-Doppler Study. Heart Vessels, 4, 162–169,

doi:10.1007/BF02058429.

Ye, J., Zheng, P., Hassan, M., Jiang, S., & Zheng, J. (2017).

Relationship of the angle between the A1 and A2

segments of the anterior cerebral artery with formation

and rupture of anterior communicating artery

aneurysm. Journal of the neurological sciences, 375,

170–174. https://doi.org/10.1016/j.jns.2017.01.062

BIODEVICES 2024 - 17th International Conference on Biomedical Electronics and Devices

158