Flow of concentrated red blood cells suspensions in ... - Ian Billanou

Fraction of blood flow ... conditions and an in situ quantitative measurement of the flow ..... However, efforts are to be made on the micro-channel architecture.
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Introduction Experimental device Measurement techniques and results Conclusion

Flow of concentrated red blood cells suspensions in micro-channels: Experimental techniques.

I. Billanou1

P. Duru1

S. Lorthois1

D. Bourrier2

M. Dilhan2

1 Groupe d’Etude sur les Milieux Poreux Institut de Mécanique des Fluides de Toulouse, IMFT. 2 Laboratoire

d’Analyse et d’Architecture des Systèmes, LAAS.

Microfluidics 2006 I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Blood micro-circulation Phase separation effect Goal of this experimental study

Blood micro-circulation What is the blood micro-circulation ?

Blood micro-circulation: circulation within small vessels, (diameter range between 4µm to 100µm).

Functions of the micro-circulation Transport and exchanges blood/tissues oxygen, nutrients, waste Controle and regulation At short term: diameter variations At long term: architecture modifications I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Blood micro-circulation Phase separation effect Goal of this experimental study

Blood micro-circulation

Architecture Three-dimensional network Ratio surface/volume (5mm2 /mm3 ) Heterogeneity

The blood Red blood cells (RBCs) suspensions in plasma Haematocrit: 45 % (Ratio of the RBCs volume over the total volume)

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Blood micro-circulation Phase separation effect Goal of this experimental study

Blood micro-circulation

Architecture Three-dimensional network Ratio surface/volume (5mm2 /mm3 ) Heterogeneity

The blood Red blood cells (RBCs) suspensions in plasma Haematocrit: 45 % (Ratio of the RBCs volume over the total volume)

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Blood micro-circulation Phase separation effect Goal of this experimental study

Blood micro-circulation

Architecture Three-dimensional network Ratio surface/volume (5mm2 /mm3 ) Heterogeneity

The blood Red blood cells (RBCs) suspensions in plasma Haematocrit: 45 % (Ratio of the RBCs volume over the total volume)

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Blood micro-circulation Phase separation effect Goal of this experimental study

Phase separation effect What is the phase separation effect ?

RBCs and plasma may be distributed non-proportionally between the daughter vessels, one receiving a higher RBC haematocrit than the feeding vessel, and the other receiving a lower one. ⇒ This effect induces a tremendous heterogeneity of the haematocrit from vessel to vessel in microvascular networks.

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Blood micro-circulation Phase separation effect Goal of this experimental study

Phase separation effect Experimental in vivo studies. [Pries et al. 1989] . Relevant parameters: Inlet haematocrit Fraction of blood flow entering each daughter vessel

. Empirical law. . Range of validity not explicit.

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Blood micro-circulation Phase separation effect Goal of this experimental study

Phase separation effect Experimental in vivo studies. [Pries et al. 1989] . Relevant parameters: Inlet haematocrit Fraction of blood flow entering each daughter vessel

Aim: . Clarify this phenomenological description in the case of capillary vessels (4 to 20 µm).

. Empirical law. . Range of validity not explicit.

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Blood micro-circulation Phase separation effect Goal of this experimental study

Goal of this experimental study

Goals of this study are:

use of asymetric bifurcations, simultaneously have a rigorous control of the experimental conditions and an in situ quantitative measurement of the flow parameters. design the experimental set up for a regime which is seldom studied (highly concentrated RBCs suspensions, small ratio between RBC and vessel diameters), I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Micro-channels Overview Suspensions Visualization Flow rate measurement

Plan 1

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Introduction Blood micro-circulation Phase separation effect Goal of this experimental study Experimental device Micro-channels Overview Suspensions Visualization Flow rate measurement Measurement techniques and results Particle Tracking Velocimetry, PTV DualSlit Conclusion I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Micro-channels Overview Suspensions Visualization Flow rate measurement

Micro-channels

. Produced with the soft lithography technique. . Material: PolyDiMethylSiloxane (PDMS). A microbifucation

. Three kinds of microchannels: single channel 100x15 µm2 and 50x10 µm2 single channel with cross section constriction 20x15 µm2 and 10x10 µm2

bifurcation

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Micro-channels Overview Suspensions Visualization Flow rate measurement

Overview

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Micro-channels Overview Suspensions Visualization Flow rate measurement

Suspensions Red blood cells suspensions: Blood collected from healthy volunteers by finger-stick, Diluted in a phosphate buffered saline (PBS) solution containing 1.5mg/ml EDTA for anticoagulation, RBCs washed by successive centrifugation, RBCs suspended in PBS containing glucose and Bovine Serum Albumin, Haematocrit adjusted to the desired value.

Latex suspensions: Small diameter particles: monodisperse particles ( = 2µm), Isodensity (water + glycerol), Concentrations adjusted to the desired value. I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Micro-channels Overview Suspensions Visualization Flow rate measurement

Visualization Flow rate: 0.01 µl/min ; haematocrit: 10% ; channel: 100x15 µm2

Flow rate: 0.01 µl/min ; haematocrit: 45% ; channel: 100x15 µm2

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Micro-channels Overview Suspensions Visualization Flow rate measurement

Flow rate measurement The first parameter to measure is the flow rate.

In the parameters range of interest, in situ measurement of the flow rate is a difficult task.

However, the DualSlit technique, widely used in microvascular research, may be able to provide valuable insights about blood flow control.

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

Plan 1

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Introduction Blood micro-circulation Phase separation effect Goal of this experimental study Experimental device Micro-channels Overview Suspensions Visualization Flow rate measurement Measurement techniques and results Particle Tracking Velocimetry, PTV DualSlit Conclusion I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

Particle Tracking Velocimetry A REFERENCE MEASUREMENT METHODE. Using this method as a reference requires to validate it. ⇒ Comparison between the results obtained and the theoretical model. [Patzek & Silin 2001]

The theoretical velocity profile is valid for: channels with rectangular cross-section, a creeping flow, a newtonian fluid.

This is why we used low concentration latex supensions for validation of the PTV method. I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

Particle Tracking Velocimetry PRINCIPLE Use of images triplets.

Data treatment for each particle. find the center of mass, detect the movement from one image to another, evaluate the velocity.

Repeat for a series of triplets. I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

Particle Tracking Velocimetry PRINCIPLE Use of images triplets.

Data treatment for each particle. find the center of mass, detect the movement from one image to another, evaluate the velocity.

Repeat for a series of triplets. I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

Particle Tracking Velocimetry PRINCIPLE Use of images triplets.

Data treatment for each particle. find the center of mass, detect the movement from one image to another, evaluate the velocity.

Repeat for a series of triplets. I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

Particle Tracking Velocimetry RESULTS Imposed flow rate: Q = 0, 1 µl/min

Data treatment: . Channel width is decomposed in slices.

canal 100x15 µm2 I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

Particle Tracking Velocimetry RESULTS Imposed flow rate: Q = 0, 1 µl/min

Data treatment: . Channel width is decomposed in slices. . Mean velocity is calculated in each slice.

canal 100x15 µm2 I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

Particle Tracking Velocimetry RESULTS Imposed flow rate: Q = 0, 1 µl/min

Data treatment: . Channel width is decomposed in slices. . Mean velocity is calculated in each slice. . Mean flow rate is fitted to the theoretical profile averaged over channel depth.

canal 100x15 µm2 I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

Particle Tracking Velocimetry RESULTS Imposed flow rate: Q = 0, 1 µl/min

The mean velocity calculation for each triplet gives the mean time evolution.

canal 100x15 µm2 I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

Particle Tracking Velocimetry CONCLUSION

Results have shown that PTV can be used as a reference method. PTV is useful to follow the flow rate variations in time. If these variations are small, PTV gives a good approximation of the flow rate. PTV does not work with highly concentrated suspensions.

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

DualSlit, Wayland & Johnson, 1974 A TEMPORAL CORRELATION TECHNIQUE.

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

DualSlit, Wayland & Johnson, 1974 A TEMPORAL CORRELATION TECHNIQUE.

f (τ ) = Vexp =

R T −x 0

s1(t).s2(t + τ )dt

∆ Γ

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

DualSlit, Wayland & Johnson, 1974

A model is proposed in the literature. (Wayland & Johnson, 1974) Vds =

R 2 R V (y )dy V (y )dy

Reason why Vexp correspond to Vds is not clear in the literature.

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

DualSlit, Wayland & Johnson, 1974 RESULTS : LATEX SUSPENSIONS Imposed flow rate: Q = 0.01 µl/min, Channel: 100x15 µm2 , latex suspension: C=0.5%. Velocity profile obtained by DualSlit.

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

DualSlit, Wayland & Johnson, 1974 RESULTS : LATEX SUSPENSIONS Imposed flow rate: Q = 0.01 µl/min, Channel: 100x15 µm2 , latex suspension: C=0.5%. The flow rate obtained by DualSlit is always under-evaluated.

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

DualSlit, Wayland & Johnson, 1974 RESULTS : LATEX SUSPENSIONS Imposed flow rate: Q = 0.01 µl/min, Channel: 100x15 µm2 , latex suspension: C=0.5%. Comparison with the PTV result.

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

DualSlit, Wayland & Johnson, 1974 RESULTS : RBCs SUSPENSIONS Imposed flow rate: Q = 5 nl/min, Channel: 100x15 µm2 , RBCs suspension: H≈10%. [Green]: Theoretical profile corresponding to imposed flow rate. [Blue]: Profile obtained by DualSlit. [Red]: Mean velocity, (imposed flow rate/channel section). I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Particle Tracking Velocimetry, PTV DualSlit

DualSlit, Wayland & Johnson, 1974 CONCLUSION

Results are encouraging. Velocity profiles obtained by this method (DualSlit) seem to contain some physical informations. A calibration of the method according to the imposed flow rate could be considered as soon as fluctuation problems will be solved.

I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Plan 1

2

3

4

Introduction Blood micro-circulation Phase separation effect Goal of this experimental study Experimental device Micro-channels Overview Suspensions Visualization Flow rate measurement Measurement techniques and results Particle Tracking Velocimetry, PTV DualSlit Conclusion I.Billanou

µFlu’06-27

Introduction Experimental device Measurement techniques and results Conclusion

Conclusion An experimental device for the in vitro study of the phase separation effect has been presented. To the best of our knowledge this device is the first one allowing the study of RBCs flow in asymetric micro-bifurcations made of square channels. Encouraging results were obtained. However, efforts are to be made on the micro-channel architecture.

I.Billanou

µFlu’06-27