Velocimetry of red blood cells in microvessels by the dual-slit method: Effect of velocity gradients

Roman, Sophie; Lorthois, Sylvie; Duru, Paul; Risso, Frédéric

doi:10.1016/j.mvr.2012.08.006

Cited by 30 publications

(33 citation statements)

References 37 publications

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“…As explained earlier, the measurement of RBC maximal velocity profiles by dual-slit, following Roman et al 40 and described by Equation (2), is at the core of the methodology developed in the present paper. First, we discuss the measured velocity profiles before turning to the validation of the RBC and suspending fluid flow rate measurement techniques proposed in Section II.…”

Section: Resultsmentioning

confidence: 99%

“…It must be mentioned that this process therefore induces the existence of a "step" at the junction between two microchannels of different depths. More details about the microfabrication process (e.g., on moulding and bonding of the PDMS microsystems) can be found in Roman et al 40 The actual dimensions of the microchannels are within 10% of the desired ones and checked a posteriori by measuring the eight of each positive micro-channel on the SU8 master using a profilometer and the width of each PDMS channel using our own optical system and a calibration probe. The actual values are used in the whole following when needed to deduce integrated quantities, such as blood flow.…”

Section: Microchannelsmentioning

confidence: 99%

“…It consists of a mixture of concentrated GASP and Optiprep (Axis Shield), a density gradient fluid. The method to prepare this iso-density solution is detailed by Roman et al 40 Finally, the washed RBC pellet is diluted in this solution at the desired concentration, i.e., with feed hematocrit ranging from 5% to 60% of RBC. This is a large range by comparison with most previous in vitro studies, where a unique value of the feed hematocrit has been used, ranging from 10% in Ref.…”

Section: Rbc Suspensionsmentioning

confidence: 99%

“…These parameters are chosen according to Ref. 40 to ensure high-quality dual-slit measurements. Images of RBCs flowing in the four types of microbifurcations are presented in Figure 1.…”

Section: Imagingmentioning

confidence: 99%

“…Velocity profiles of RBCs are measured by the optimized dual-slit technique introduced by Roman et al 40 This temporal correlation technique only converges in steady state conditions. Then, it allows the measurement of a maximal velocity profile, V max ðxÞ, that corresponds to the FIG.…”

Section: Rbc Velocity Profilesmentioning

confidence: 99%

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Going beyond 20 μm-sized channels for studying red blood cell phase separation in microfluidic bifurcations

et al. 2016

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Despite the development of microfluidics, experimental challenges are considerable for achieving a quantitative study of phase separation, i.e., the non-proportional distribution of Red Blood Cells (RBCs) and suspending fluid, in microfluidic bifurcations with channels smaller than 20 lm. Yet, a basic understanding of phase separation in such small vessels is needed for understanding the coupling between microvascular network architecture and dynamics at larger scale. Here, we present the experimental methodologies and measurement techniques developed for that purpose for RBC concentrations (tube hematocrits) ranging between 2% and 20%. The maximal RBC velocity profile is directly measured by a temporal cross-correlation technique which enables to capture the RBC slip velocity at walls with high resolution, highlighting two different regimes (flat and more blunted ones) as a function of RBC confinement. The tube hematocrit is independently measured by a photometric technique. The RBC and suspending fluid flow rates are then deduced assuming the velocity profile of a Newtonian fluid with no slip at walls for the latter. The accuracy of this combination of techniques is demonstrated by comparison with reference measurements and verification of RBC and suspending fluid mass conservation at individual bifurcations. The present methodologies are much more accurate, with less than 15% relative errors, than the ones used in previous in vivo experiments. Their potential for studying steady state phase separation is demonstrated, highlighting an unexpected decrease of phase separation with increasing hematocrit in symmetrical, but not asymmetrical, bifurcations and providing new reference data in regimes where in vitro results were previously lacking. Published by AIP Publishing. [http://dx

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Section: Resultsmentioning

confidence: 99%

Section: Microchannelsmentioning

confidence: 99%

Section: Rbc Suspensionsmentioning

confidence: 99%

“…These parameters are chosen according to Ref. 40 to ensure high-quality dual-slit measurements. Images of RBCs flowing in the four types of microbifurcations are presented in Figure 1.…”

Section: Imagingmentioning

confidence: 99%

Section: Rbc Velocity Profilesmentioning

confidence: 99%

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Going beyond 20 μm-sized channels for studying red blood cell phase separation in microfluidic bifurcations

et al. 2016

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Ghost Cells for Mechanical Circulatory Support In Vitro Testing: A Novel Large Volume Production

Schöps

Clauser

Menne

et al. 2020

Biotechnology Journal

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The aim of this work is to establish a large volume batch production system to produce sufficient volumes of ghost cells to facilitate hemolysis testing of mechanical circulatory support devices. A volume of more than 405 mL with a hematocrit of at least 28% is required to perform in vitro hemolysis testing of mechanical circulatory support devices according to international standards. The established ghost cell production method performed at the institute is limited to 3.1 mL of concentrated cells, that is, cells with 100% hematocrit, due to predominantly manual process steps. Through semi‐automation of the existing method by using the large volume batch production system, productivity is increased 60‐fold to 188 mL while almost doubling process efficiency to 23.5%. Time‐consuming manual work such as pipetting is now supported by sensor‐based process engineering. With the help of the large volume batch production system, the objective of producing large quantities of ghost cells is successfully achieved. Thus, this work lays the foundation for spatially resolved hemolysis evaluation of mechanical circulatory support devices in combination with the small‐scale fluorescent hemolysis detection method.

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Enhanced three-dimensional particle detection in microcirculation experiments with defocus particle tracking and ghost red blood cells

Coutinho,

Warlitz,

Silva-Santos

et al. 2024

Exp Fluids

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Experimental investigations on the motion of rigid particles in microcirculation environments are still scarce owing to the three-dimensional (3D) motion of the particles and to the particle image masking due to the presence of the red blood cells (RBCs). Despite the recent progress on the 3D tracking of rigid particles in RBC flows with defocus particle tracking (DPT) methods, the problem of particle image masking remains to be solved. Here, we propose, test, and evaluate the use hemoglobin-free RBCs, also known as ghost RBCs, as a replacement for normal RBCs in experiments with rigid particles in microcirculation environments. We performed DPT measurements of a pressure-driven flow of normal and ghost RBC suspensions seeded with rigid particles at three different flow rates. We show that the quasi-transparent appearance of ghost RBCs, as a result of the lack of hemoglobin, eliminates the RBC-induced masking of the defocused particle images and allows to achieve the particle matching standards found in cell-free experiments. In fact, ghost RBC suspensions enable the tracking of the rigid particles across the entire height of the microchannel, which was not possible in normal RBC flows. On a fluid dynamic level, we show that ghost RBC suspensions provide similar conditions to normal RBCs in terms of the velocity of the rigid particles and the rigid particles exhibit similar lateral dynamics in both types of cell suspensions. In essence, the findings from this work demonstrate that ghost RBCs are a well-suited replacement for normal RBCs in experiments aiming at deciphering the motion of rigid particles in microcirculation environments. Graphical abstract

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Velocimetry of red blood cells in microvessels by the dual-slit method: Effect of velocity gradients

Cited by 30 publications

References 37 publications

Going beyond 20 μm-sized channels for studying red blood cell phase separation in microfluidic bifurcations

Going beyond 20 μm-sized channels for studying red blood cell phase separation in microfluidic bifurcations

Ghost Cells for Mechanical Circulatory Support In Vitro Testing: A Novel Large Volume Production

Enhanced three-dimensional particle detection in microcirculation experiments with defocus particle tracking and ghost red blood cells

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