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Effects of Aggregation on Blood Sedimentation and Conductivity.

Zhbanov A, Yang S - PLoS ONE (2015)

Bottom Line: Using experimental measurements and theoretical calculations, we show that the initial increase in blood conductivity was indeed caused by aggregation, while the subsequent decrease in conductivity resulted from the deposition of erythrocytes.We present a method for calculating blood conductivity based on effective medium theory.In the future, our method could be examined as a potential means of accelerating ESR tests in clinical practice.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical System Engineering, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea.

ABSTRACT
The erythrocyte sedimentation rate (ESR) test has been used for over a century. The Westergren method is routinely used in a variety of clinics. However, the mechanism of erythrocyte sedimentation remains unclear, and the 60 min required for the test seems excessive. We investigated the effects of cell aggregation during blood sedimentation and electrical conductivity at different hematocrits. A sample of blood was drop cast into a small chamber with two planar electrodes placed on the bottom. The measured blood conductivity increased slightly during the first minute and decreased thereafter. We explored various methods of enhancing or retarding the erythrocyte aggregation. Using experimental measurements and theoretical calculations, we show that the initial increase in blood conductivity was indeed caused by aggregation, while the subsequent decrease in conductivity resulted from the deposition of erythrocytes. We present a method for calculating blood conductivity based on effective medium theory. Erythrocytes are modeled as conducting spheroids surrounded by a thin insulating membrane. A digital camera was used to investigate the erythrocyte sedimentation behavior and the distribution of the cell volume fraction in a capillary tube. Experimental observations and theoretical estimations of the settling velocity are provided. We experimentally demonstrate that the disaggregated cells settle much slower than the aggregated cells. We show that our method of measuring the electrical conductivity credibly reflected the ESR. The method was very sensitive to the initial stage of aggregation and sedimentation, while the sedimentation curve for the Westergren ESR test has a very mild slope in the initial time. We tested our method for rapid estimation of the Westergren ESR. We show a correlation between our method of measuring changes in blood conductivity and standard Westergren ESR method. In the future, our method could be examined as a potential means of accelerating ESR tests in clinical practice.

No MeSH data available.


Related in: MedlinePlus

Schematic drawing of the device and experimental setup that were used to measure blood conductivity.(A) Cross-section of the PDMS chamber. (B) Shapes and sizes of the gold-plated electrodes on the bottom of the chamber. (C) The appearance of the measuring system. Blood samples are loaded into the chamber using a pipette. (D) Photograph of the experimental setup. Calibration using air. (E) Photograph of the measuring PDMS chamber with two planar electrodes.
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pone.0129337.g001: Schematic drawing of the device and experimental setup that were used to measure blood conductivity.(A) Cross-section of the PDMS chamber. (B) Shapes and sizes of the gold-plated electrodes on the bottom of the chamber. (C) The appearance of the measuring system. Blood samples are loaded into the chamber using a pipette. (D) Photograph of the experimental setup. Calibration using air. (E) Photograph of the measuring PDMS chamber with two planar electrodes.

Mentions: A schematic drawing of the device that we used to measure blood conductivity is shown in Fig 1A. The device is prepared following the conventional Micro-Electro-Mechanical Systems process. It consists of a polydimethylsiloxane (PDMS) chamber with a square cross-section (sides: 4 mm wide and 5 mm deep, as shown in Fig 1A), and two gold-plated two-dimensional planar electrodes that are set 1200 μm apart and each have a width 300 μm (Fig 1B). The portion of the electrode has contact with blood is about 4 mm in length. The planar electrodes were fabricated using a typical lithographic process. The positive photoresist GXR-601 (AZ Electronic Materials, Anseong, Korea) was patterned on a glass substrate sputtered with 300-nm gold and 30-nm chromium for adhesion. After the lithography patterning of the electrodes, the substrate was immersed in gold etchant (Sigma Aldrich, Corp., St. Louis, MO, United States) to remove gold and chromium. The well-like chamber illustrated in Fig 1 was created in a PDMS block using a 4 × 4 mm punch. Subsequently, the glass-bottomed substrate (integrated with the electrodes) was bonded with the PDMS block via an O2 plasma process.


Effects of Aggregation on Blood Sedimentation and Conductivity.

Zhbanov A, Yang S - PLoS ONE (2015)

Schematic drawing of the device and experimental setup that were used to measure blood conductivity.(A) Cross-section of the PDMS chamber. (B) Shapes and sizes of the gold-plated electrodes on the bottom of the chamber. (C) The appearance of the measuring system. Blood samples are loaded into the chamber using a pipette. (D) Photograph of the experimental setup. Calibration using air. (E) Photograph of the measuring PDMS chamber with two planar electrodes.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4457804&req=5

pone.0129337.g001: Schematic drawing of the device and experimental setup that were used to measure blood conductivity.(A) Cross-section of the PDMS chamber. (B) Shapes and sizes of the gold-plated electrodes on the bottom of the chamber. (C) The appearance of the measuring system. Blood samples are loaded into the chamber using a pipette. (D) Photograph of the experimental setup. Calibration using air. (E) Photograph of the measuring PDMS chamber with two planar electrodes.
Mentions: A schematic drawing of the device that we used to measure blood conductivity is shown in Fig 1A. The device is prepared following the conventional Micro-Electro-Mechanical Systems process. It consists of a polydimethylsiloxane (PDMS) chamber with a square cross-section (sides: 4 mm wide and 5 mm deep, as shown in Fig 1A), and two gold-plated two-dimensional planar electrodes that are set 1200 μm apart and each have a width 300 μm (Fig 1B). The portion of the electrode has contact with blood is about 4 mm in length. The planar electrodes were fabricated using a typical lithographic process. The positive photoresist GXR-601 (AZ Electronic Materials, Anseong, Korea) was patterned on a glass substrate sputtered with 300-nm gold and 30-nm chromium for adhesion. After the lithography patterning of the electrodes, the substrate was immersed in gold etchant (Sigma Aldrich, Corp., St. Louis, MO, United States) to remove gold and chromium. The well-like chamber illustrated in Fig 1 was created in a PDMS block using a 4 × 4 mm punch. Subsequently, the glass-bottomed substrate (integrated with the electrodes) was bonded with the PDMS block via an O2 plasma process.

Bottom Line: Using experimental measurements and theoretical calculations, we show that the initial increase in blood conductivity was indeed caused by aggregation, while the subsequent decrease in conductivity resulted from the deposition of erythrocytes.We present a method for calculating blood conductivity based on effective medium theory.In the future, our method could be examined as a potential means of accelerating ESR tests in clinical practice.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical System Engineering, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea.

ABSTRACT
The erythrocyte sedimentation rate (ESR) test has been used for over a century. The Westergren method is routinely used in a variety of clinics. However, the mechanism of erythrocyte sedimentation remains unclear, and the 60 min required for the test seems excessive. We investigated the effects of cell aggregation during blood sedimentation and electrical conductivity at different hematocrits. A sample of blood was drop cast into a small chamber with two planar electrodes placed on the bottom. The measured blood conductivity increased slightly during the first minute and decreased thereafter. We explored various methods of enhancing or retarding the erythrocyte aggregation. Using experimental measurements and theoretical calculations, we show that the initial increase in blood conductivity was indeed caused by aggregation, while the subsequent decrease in conductivity resulted from the deposition of erythrocytes. We present a method for calculating blood conductivity based on effective medium theory. Erythrocytes are modeled as conducting spheroids surrounded by a thin insulating membrane. A digital camera was used to investigate the erythrocyte sedimentation behavior and the distribution of the cell volume fraction in a capillary tube. Experimental observations and theoretical estimations of the settling velocity are provided. We experimentally demonstrate that the disaggregated cells settle much slower than the aggregated cells. We show that our method of measuring the electrical conductivity credibly reflected the ESR. The method was very sensitive to the initial stage of aggregation and sedimentation, while the sedimentation curve for the Westergren ESR test has a very mild slope in the initial time. We tested our method for rapid estimation of the Westergren ESR. We show a correlation between our method of measuring changes in blood conductivity and standard Westergren ESR method. In the future, our method could be examined as a potential means of accelerating ESR tests in clinical practice.

No MeSH data available.


Related in: MedlinePlus