Bubble-induced damping in displacement-driven microfluidic flows

Lee, Jong-Ho; Rahman, Faizur; Laoui, Tahar; Karnik, Rohit

doi:10.1103/physreve.86.026301

Cited by 17 publications

(12 citation statements)

References 14 publications

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“…A 15 W centrifugal pump circulated the working fluid through the circuit at a constant flow rate. A 0.5 L air container was installed as a fluidic low-pass filter using a three-way connector to stabilize possible fluctuations in flow rate [27] , [28] . To measure the flow rate, a variable area-type flow meter (Visi-Float, Dwyer Instruments, Inc., Michigan, USA) was installed after proper re-calibration with the working fluid.…”

Section: Methodsmentioning

confidence: 99%

Fluid-Dynamic Optimal Design of Helical Vascular Graft for Stenotic Disturbed Flow

Hwang

Choi

et al. 2014

PLoS ONE

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Although a helical configuration of a prosthetic vascular graft appears to be clinically beneficial in suppressing thrombosis and intimal hyperplasia, an optimization of a helical design has yet to be achieved because of the lack of a detailed understanding on hemodynamic features in helical grafts and their fluid dynamic influences. In the present study, the swirling flow in a helical graft was hypothesized to have beneficial influences on a disturbed flow structure such as stenotic flow. The characteristics of swirling flows generated by helical tubes with various helical pitches and curvatures were investigated to prove the hypothesis. The fluid dynamic influences of these helical tubes on stenotic flow were quantitatively analysed by using a particle image velocimetry technique. Results showed that the swirling intensity and helicity of the swirling flow have a linear relation with a modified Germano number (Gn*) of the helical pipe. In addition, the swirling flow generated a beneficial flow structure at the stenosis by reducing the size of the recirculation flow under steady and pulsatile flow conditions. Therefore, the beneficial effects of a helical graft on the flow field can be estimated by using the magnitude of Gn*. Finally, an optimized helical design with a maximum Gn* was suggested for the future design of a vascular graft.

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Section: Methodsmentioning

confidence: 99%

Fluid-Dynamic Optimal Design of Helical Vascular Graft for Stenotic Disturbed Flow

Hwang

Choi

et al. 2014

PLoS ONE

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“…However, during the process of supplying a blood sample into a microfluidic device, the syringe pump causes fluidic instability at low flow rates [22]. To stabilize unstable flows resulting from the syringe pump, several techniques including air cavity in a driving syringe [23] or microfluidic channel [24,25], portable air cavity unit [22,26], and flexible compliance unit [27][28][29][30][31][32], were demonstrated in microfluidic systems. These methods act on the compliance element in the fluidic circuit model.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Air Compliance Effect on Measurement of Mechanical Properties of Blood Sample Flowing in Microfluidic Channels

Kang

2020

Micromachines

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Air compliance has been used effectively to stabilize fluidic instability resulting from a syringe pump. It has also been employed to measure blood viscosity under constant shearing flows. However, due to a longer time delay, it is difficult to quantify the aggregation of red blood cells (RBCs) or blood viscoelasticity. To quantify the mechanical properties of blood samples (blood viscosity, RBC aggregation, and viscoelasticity) effectively, it is necessary to quantify contributions of air compliance to dynamic blood flows in microfluidic channels. In this study, the effect of air compliance on measurement of blood mechanical properties was experimentally quantified with respect to the air cavity in two driving syringes. Under periodic on–off blood flows, three mechanical properties of blood samples were sequentially obtained by quantifying microscopic image intensity (<I>) and interface (α) in a co-flowing channel. Based on a differential equation derived with a fluid circuit model, the time constant was obtained by analyzing the temporal variations of β = 1/(1–α). According to experimental results, the time constant significantly decreased by securing the air cavity in a reference fluid syringe (~0.1 mL). However, the time constant increased substantially by securing the air cavity in a blood sample syringe (~0.1 mL). Given that the air cavity in the blood sample syringe significantly contributed to delaying transient behaviors of blood flows, it hindered the quantification of RBC aggregation and blood viscoelasticity. In addition, it was impossible to obtain the viscosity and time constant when the blood flow rate was not available. Thus, to measure the three aforementioned mechanical properties of blood samples effectively, the air cavity in the blood sample syringe must be minimized (Vair, R = 0). Concerning the air cavity in the reference fluid syringe, it must be sufficiently secured about Vair, R = 0.1 mL for regulating fluidic instability because it does not affect dynamic blood flows.

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“…A 0.5-L air container was installed as a fluidic low-pass filter using a three-way connector to stabilize possible fluctuations in the flow rate. 31,32 To measure the flow rate, a variable area-type flow meter (Visi-Float; Dwyer Instruments Inc., USA) was installed after recalibration of the working fluid. The internal fluid valve of the flow meter controlled the flow rate.…”

Section: Methodsmentioning

confidence: 99%

“…A 15-W centrifugal pump circulated the working fluid through the circuit at a constant flow rate. A 0.5-L air container was installed as a fluidic low-pass filter using a threeway connector to stabilize possible fluctuations in the flow rate 31,32. To measure the flow rate, a variable areatype flow meter (Visi-Float; Dwyer Instruments Inc., USA) was installed after recalibration of the working…”

mentioning

confidence: 99%

Effect of swirling blood flow on vortex formation at post-stenosis

Choi

Park

et al. 2015

Proc Inst Mech Eng H

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Various clinical observations reported that swirling blood flow is a normal physiological flow pattern in various vasculatures. The swirling flow has beneficial effects on blood circulation through the blood vessels. It enhances oxygen transfer and reduces low-density lipoprotein concentration in the blood vessel by enhancing cross-plane mixing of the blood. However, the fluid-dynamic roles of the swirling flow are not yet fully understood. In this study, inhibition of material deposition at the post-stenosis region by the swirling flow was observed. To reveal the underlying fluid-dynamic characteristics, pathline flow visualization and time-resolved particle image velocimetry measurements were conducted. Results showed that the swirling inlet flow increased the development of vortices at near wall region of the post-stenosis, which can suppress further development of stenosis by enhancing transport and mixing of the blood flow. The fluid-dynamic characteristics obtained in this study would be useful for improving hemodynamic characteristics of vascular grafts and stents in which the stenosis frequently occurred. Moreover, the time-resolved particle image velocimetry measurement technique and vortex identification method employed in this study would be useful for investigating the fluid-dynamic effects of the swirling flow on various vascular environments.

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Bubble-induced damping in displacement-driven microfluidic flows

Cited by 17 publications

References 14 publications

Fluid-Dynamic Optimal Design of Helical Vascular Graft for Stenotic Disturbed Flow

Fluid-Dynamic Optimal Design of Helical Vascular Graft for Stenotic Disturbed Flow

Experimental Investigation of Air Compliance Effect on Measurement of Mechanical Properties of Blood Sample Flowing in Microfluidic Channels

Effect of swirling blood flow on vortex formation at post-stenosis

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