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Kang YJ. Biomechanical Investigation of Red Cell Sedimentation Using Blood Shear Stress and Blood Flow Image in a Capillary Chip. MICROMACHINES 2023; 14:1594. [PMID: 37630130 PMCID: PMC10456426 DOI: 10.3390/mi14081594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 08/01/2023] [Accepted: 08/11/2023] [Indexed: 08/27/2023]
Abstract
Blood image intensity has been used to detect erythrocyte sedimentation rate (ESR). However, it does not give information on the biophysical properties of blood samples under continuous ESR. In this study, to quantify mechanical variations of blood under continuous ESR, blood shear stress and blood image intensity were obtained by analyzing blood flows in the capillary channel. A blood sample is loaded into a driving syringe to demonstrate the proposed method. The blood flow rate is set in a periodic on-off pattern. A blood sample is then supplied into a capillary chip, and microscopic blood images are captured at specific intervals. Blood shear stress is quantified from the interface of the bloodstream in the coflowing channel. τ0 is defined as the maximum shear stress obtained at the first period. Simultaneously, ESRτ is then obtained by analyzing temporal variations of blood shear stress for every on period. AII is evaluated by analyzing the temporal variation of blood image intensity for every off period. According to the experimental results, a shorter period of T = 4 min and no air cavity contributes to the high sensitivity of the two indices (ESRτ and AII). The τ0 exhibits substantial differences with respect to hematocrits (i.e., 30-50%) as well as diluents. The ESRτ and AII showed a reciprocal relationship with each other. Three suggested properties represented substantial differences for suspended blood samples (i.e., hardened red blood cells, different concentrations of dextran solution, and fibrinogen). In conclusion, the present method can detect variations in blood samples under continuous ESR effectively.
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Affiliation(s)
- Yang Jun Kang
- Department of Mechanical Engineering, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
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Kang YJ. Quantification of Blood Viscoelasticity under Microcapillary Blood Flow. MICROMACHINES 2023; 14:814. [PMID: 37421047 DOI: 10.3390/mi14040814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 03/31/2023] [Accepted: 04/02/2023] [Indexed: 07/09/2023]
Abstract
Blood elasticity is quantified using a single compliance model by analyzing pulsatile blood flow. However, one compliance coefficient is influenced substantially by the microfluidic system (i.e., soft microfluidic channels and flexible tubing). The novelty of the present method comes from the assessment of two distinct compliance coefficients, one for the sample and one for the microfluidic system. With two compliance coefficients, the viscoelasticity measurement can be disentangled from the influence of the measurement device. In this study, a coflowing microfluidic channel was used to estimate blood viscoelasticity. Two compliance coefficients were suggested to denote the effects of the polydimethylsiloxane (PDMS) channel and flexible tubing (C1), as well as those of the RBC (red blood cell) elasticity (C2), in a microfluidic system. On the basis of the fluidic circuit modeling technique, a governing equation for the interface in the coflowing was derived, and its analytical solution was obtained by solving the second-order differential equation. Using the analytic solution, two compliance coefficients were obtained via a nonlinear curve fitting technique. According to the experimental results, C2/C1 is estimated to be approximately 10.9-20.4 with respect to channel depth (h = 4, 10, and 20 µm). The PDMS channel depth contributed simultaneously to the increase in the two compliance coefficients, whereas the outlet tubing caused a decrease in C1. The two compliance coefficients and blood viscosity varied substantially with respect to homogeneous hardened RBCs or heterogeneous hardened RBCs. In conclusion, the proposed method can be used to effectively detect changes in blood or microfluidic systems. In future studies, the present method can contribute to the detection of subpopulations of RBCs in the patient's blood.
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Affiliation(s)
- Yang Jun Kang
- Department of Mechanical Engineering, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
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Kang YJ, Serhrouchni S, Makhro A, Bogdanova A, Lee SS. Simple Assessment of Red Blood Cell Deformability Using Blood Pressure in Capillary Channels for Effective Detection of Subpopulations in Red Blood Cells. ACS OMEGA 2022; 7:38576-38588. [PMID: 36340168 PMCID: PMC9631408 DOI: 10.1021/acsomega.2c04027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
Assessment of red blood cell (RBC) deformability as a biomarker requires expensive equipment to induce and monitor deformation. In this study, we present a simple method for quantifying RBC deformability. We designed a microfluidic channel consisting of a micropillar channel and a coflowing channel connected in series. When blood (loading volume = 100 μL) was injected continuously into the device under constant pressure (1 bar), we monitored the boundary position of the blood and the reference flow in the coflowing channel. A decrease in the deformability of RBCs results in a growing pressure drop in the micropillar channel, which is mirrored by a decrease in blood pressure in the coflowing channel. Analysis of this temporal variation in blood pressure allowed us to define the clogging index (CI) as a new marker of RBC deformability. As a result of the analytical study and numerical simulation, we have demonstrated that the coflowing channel may serve as a pressure sensor that allows the measurement of blood pressure with accuracy. We have shown experimentally that a higher hematocrit level (i.e., more than 40%) does not have a substantial influence on CI. The CI tended to increase to a higher degree in glutaraldehyde-treated hardened RBCs. Furthermore, we were able to resolve the difference in deformability of RBCs between two different RBC density subfractions in human blood. In summary, our approach using CI provides reliable information on the deformability of RBCs, which is comparable to the readouts obtained by ektacytometry. We believe that our microfluidic device would be a useful tool for evaluating the deformability of RBCs, which does not require expensive instruments (e.g., high-speed camera) or time-consuming micro-PIV analysis.
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Affiliation(s)
- Yang Jun Kang
- Department
of Mechanical Engineering, Chosun University, Gwangju501-759, Republic of Korea
| | - Sami Serhrouchni
- Institute
of Veterinary Physiology, University of
Zürich, Zürich8057, Switzerland
| | - Asya Makhro
- Institute
of Veterinary Physiology, University of
Zürich, Zürich8057, Switzerland
| | - Anna Bogdanova
- Institute
of Veterinary Physiology, University of
Zürich, Zürich8057, Switzerland
- Center
for Clinical Studies (ZKS), Vetsuisse Faculty, University of Zürich, Zürich8006, Switzerland
| | - Sung Sik Lee
- Scientific
Center for Optical and Electron Microscopy, ETH Zürich, Zürich8093, Switzerland
- Department
of Biology, Institute of Biochemistry, ETH
Zürich, Zürich8093, Switzerland
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Kang YJ. Red Blood Cell Sedimentation Index Using Shear Stress of Blood Flow in Microfluidic Channel. BIOSENSORS 2022; 12:bios12070547. [PMID: 35884350 PMCID: PMC9312500 DOI: 10.3390/bios12070547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 07/19/2022] [Accepted: 07/19/2022] [Indexed: 11/30/2022]
Abstract
Red blood cell sedimentation has been used as a promising indicator of hematological diseases and disorders. However, to address several issues (i.e., syringe installation direction, blood on-off flow control, image-based quantification, and hemodilution) raised by the previous methods, it is necessary to devise a new method for the effective quantification of red blood cell sedimentation under a constant blood flow. In this study, the shear stress of a blood flow is estimated by analyzing an interface in a co-flowing channel to quantify the red blood cell sedimentation in blood syringes filled with blood (hematocrit = 50%). A red blood cell sedimentation index is newly suggested by analyzing the temporal variations in the shear stress. According to the experimental investigation, the sedimentation index tends to decrease at a higher flow rate. A higher level of hematocrit has a negative influence on the sedimentation index. As a performance demonstration of the present method, the red blood cell sedimentation processes of various test bloods were quantitatively compared in terms of the shear stress, image intensity, and sedimentation velocity. It was found that the proposed index provided a more than 10-fold increase in sensitivity over the previous method (i.e., image intensity). Additionally, it provided more consistent results than another conventional sedimentation method (sedimentation velocity). In conclusion, the present index can be effectively adopted to monitor the red blood cell sedimentation in a 10-min blood delivery.
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Affiliation(s)
- Yang Jun Kang
- Department of Mechanical Engineering, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Korea
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Kang YJ. Sequential quantification of blood and diluent using red cell sedimentation-based separation and pressure-induced work in a microfluidic channel. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2022; 14:1194-1207. [PMID: 35234222 DOI: 10.1039/d1ay02178h] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The erythrocyte sedimentation method has been widely used to detect inflammatory diseases. However, this conventional method still has several drawbacks, such as a large blood volume (∼1 mL) and difficulty in continuous monitoring. Most importantly, image-based methods cannot quantify RBC-rich blood (blood) and RBC-free blood (diluent) simultaneously. In this study, instead of visualizing interface movement in the blood syringe, a simple method is proposed to quantify blood and diluent in microfluidic channels sequentially. The hematocrit was set to 25% to enhance RBC sedimentation and form two layers (blood and diluent) in the blood syringe. An air cavity (∼300 μL) inside the blood syringe was secured to completely remove dead volumes (∼200 μL) in fluidic paths (syringe needle and tubing). Thus, a small blood volume (Vb = 50 μL) suctioned into the blood syringe is sufficient for supplying blood and diluent in the blood channel sequentially. The relative ratio of blood resident time (RBC-to-diluent separation) was quantified using λb, which was obtained by quantifying the image intensity of blood flow. After the junction pressure (Pj) and blood volume (V) were obtained by analyzing the interface in the coflowing channel, the averaged work (Wp [Pa mm3]) was calculated and adopted to detect blood and diluent, respectively. The proposed method was then applied with various concentrations of dextran solution to detect aggregation-elevated blood. The Wp of blood and diluent exhibited substantial differences with respect to dextran solutions ranging from Cdex = 10 to Cdex = 40 mg mL-1. Moreover, λb did not exhibit substantial differences in blood with Cdex > 10 mg mL-1. The variations in λb were comparable to those of the previous method based on interface movement in the blood syringe. In conclusion, the WP could detect blood as well as diluents more effectively than λb. Furthermore, the proposed method substantially reduced the blood volume from 1 mL to 50 μL.
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Affiliation(s)
- Yang Jun Kang
- Department of Mechanical Engineering, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju, Republic of Korea.
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Assessment of Blood Biophysical Properties Using Pressure Sensing with Micropump and Microfluidic Comparator. MICROMACHINES 2022; 13:mi13030438. [PMID: 35334730 PMCID: PMC8949505 DOI: 10.3390/mi13030438] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 03/11/2022] [Accepted: 03/12/2022] [Indexed: 12/04/2022]
Abstract
To identify the biophysical properties of blood samples consistently, macroscopic pumps have been used to maintain constant flow rates in a microfluidic comparator. In this study, the bulk-sized and expensive pump is replaced with a cheap and portable micropump. A specific reference fluid (i.e., glycerin solution [40%]) with a small volume of red blood cell (RBC) (i.e., 1% volume fraction) as fluid tracers is supplied into the microfluidic comparator. An averaged velocity (<Ur>) obtained with micro-particle image velocimetry is converted into the flow rate of reference fluid (Qr) (i.e., Qr = CQ × Ac × <Ur>, Ac: cross-sectional area, CQ = 1.156). Two control variables of the micropump (i.e., frequency: 400 Hz and volt: 150 au) are selected to guarantee a consistent flow rate (i.e., COV < 1%). Simultaneously, the blood sample is supplied into the microfluidic channel under specific flow patterns (i.e., constant, sinusoidal, and periodic on-off fashion). By monitoring the interface in the comparator as well as Qr, three biophysical properties (i.e., viscosity, junction pressure, and pressure-induced work) are obtained using analytical expressions derived with a discrete fluidic circuit model. According to the quantitative comparison results between the present method (i.e., micropump) and the previous method (i.e., syringe pump), the micropump provides consistent results when compared with the syringe pump. Thereafter, representative biophysical properties, including the RBC aggregation, are consistently obtained for specific blood samples prepared with dextran solutions ranging from 0 to 40 mg/mL. In conclusion, the present method could be considered as an effective method for quantifying the physical properties of blood samples, where the reference fluid is supplied with a cheap and portable micropump.
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Kang YJ. Blood rheometer based on microflow manipulation of continuous blood flows using push-and-back mechanism. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2021; 13:4871-4883. [PMID: 34586112 DOI: 10.1039/d1ay00948f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
To understand the contributions of rheological properties to microcirculation, the simultaneous measurement of multiple rheological properties under continuous blood flows has been emphasized. However, existing methods exhibit limitations in terms of continuous and simultaneous monitoring. In this study, a simple method is suggested for simultaneously measuring four rheological properties (i.e., red blood cell (RBC) aggregation, blood viscosity, blood junction pressure, and RBC sedimentation) under a continuous blood flow. Using the push-and-back mechanism, which comprises a co-flowing channel, a test chamber, and an air compliance unit (ACU), blood is supplied to the test chamber and restored into the co-flowing channel periodically and reversely. First, RBC aggregation is quantified based on the intensity of the blood image in the test chamber. Second, blood viscosity and blood junction pressure are determined by analyzing the interface in the co-flowing channel. Lastly, RBC sedimentation is evaluated by analyzing the intensity of the blood image in the blood chamber. Based on quantitative studies involving several vital factors, the tubing length of ACU is set to L = 30 mm. The reference fluid (glycerin [20%]) is controlled in a periodic on-off manner (period = 240 s, and flow rate = 1 mL h-1). The blood flow rate is maintained at 1 mL h-1. Subsequently, the present method is used to determine the rheological properties of several blood samples with different hematocrits or diluents. Compared with previous studies, the present method yields sufficiently consistent trends with respect to the hematocrit level or concentration of dextran solution. The experimental results imply that the present method enables simultaneous and consistent measurements of four rheological properties of blood under continuous blood flows. This method can be regarded as a promising method for monitoring multiple rheological properties of blood circulating under an in vitro closed fluidic circuit.
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Affiliation(s)
- Yang Jun Kang
- Department of Mechanical Engineering, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju, South Korea.
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