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Numerical and experimental study on the development of electric sensor as for measurement of red blood cell deformability in microchannels.

Tatsumi K, Katsumoto Y, Fujiwara R, Nakabe K - Sensors (Basel) (2012)

Bottom Line: Then, a microsensor was designed and fabricated on the basis of the numerical results.Resistance measurement was carried out using samples of normal RBCs and rigidified (Ca(2+)-A23186 treated) RBCs.Visualization measurement of the cells' behavior was carried out using a high-speed camera, and the results were compared with those obtained above to evaluate the performance of the sensor.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering and Science, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan. tatsumi@me.kyoto-u.ac.jp

ABSTRACT
A microsensor that can continuously measure the deformability of a single red blood cell (RBC) in its microchannels using microelectrodes is described in this paper. The time series of the electric resistance is measured using an AC current vs. voltage method as the RBC passes between counter-electrode-type micro-membrane sensors attached to the bottom wall of the microchannel. The RBC is deformed by the shear flow created in the microchannel; the degree of deformation depends on the elastic modulus of the RBC. The resistance distribution, which is unique to the shape of the RBC, is analyzed to obtain the deformability of each cell. First, a numerical simulation of the electric field around the electrodes and RBC is carried out to evaluate the influences of the RBC height position, channel height, distance between the electrodes, electrode width, and RBC shape on the sensor sensitivity. Then, a microsensor was designed and fabricated on the basis of the numerical results. Resistance measurement was carried out using samples of normal RBCs and rigidified (Ca(2+)-A23186 treated) RBCs. Visualization measurement of the cells' behavior was carried out using a high-speed camera, and the results were compared with those obtained above to evaluate the performance of the sensor.

Show MeSH
(a) Current density distributions around the electrodes; (b–e) effects of the geometric parameter of the microchannel and electrodes on the sensor sensitivity in the case of xRBC = 0 (simulation).
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f4-sensors-12-10566: (a) Current density distributions around the electrodes; (b–e) effects of the geometric parameter of the microchannel and electrodes on the sensor sensitivity in the case of xRBC = 0 (simulation).

Mentions: The effects of the RBC height zRBC, channel height H2, distance between the sensor and ground electrodes ws, and width of the sensor electrode ls on the electric resistance R will be discussed in this section. Here, we define the resistance Rx as the value obtained when the RBC is at the streamwise location xRBC. In addition, when xRBC = 0, Rx is defined as R0, and for xRBC→∞, Rx is R∞. Naturally, R0 will be the maximum value of Rx. On the other hand, R∞ will be the resistance of the solution alone and is referred to as the base resistance. The maximum value of the resistance variation, therefore, becomes ΔR0 = R0 − R∞. Since the sensitivity of the sensor depends on the degree of ΔR0/R∞, the relationships between each of the geometric parameters of the sensor and ΔR0/R∞ are shown in Figure 4(b–e).


Numerical and experimental study on the development of electric sensor as for measurement of red blood cell deformability in microchannels.

Tatsumi K, Katsumoto Y, Fujiwara R, Nakabe K - Sensors (Basel) (2012)

(a) Current density distributions around the electrodes; (b–e) effects of the geometric parameter of the microchannel and electrodes on the sensor sensitivity in the case of xRBC = 0 (simulation).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472844&req=5

f4-sensors-12-10566: (a) Current density distributions around the electrodes; (b–e) effects of the geometric parameter of the microchannel and electrodes on the sensor sensitivity in the case of xRBC = 0 (simulation).
Mentions: The effects of the RBC height zRBC, channel height H2, distance between the sensor and ground electrodes ws, and width of the sensor electrode ls on the electric resistance R will be discussed in this section. Here, we define the resistance Rx as the value obtained when the RBC is at the streamwise location xRBC. In addition, when xRBC = 0, Rx is defined as R0, and for xRBC→∞, Rx is R∞. Naturally, R0 will be the maximum value of Rx. On the other hand, R∞ will be the resistance of the solution alone and is referred to as the base resistance. The maximum value of the resistance variation, therefore, becomes ΔR0 = R0 − R∞. Since the sensitivity of the sensor depends on the degree of ΔR0/R∞, the relationships between each of the geometric parameters of the sensor and ΔR0/R∞ are shown in Figure 4(b–e).

Bottom Line: Then, a microsensor was designed and fabricated on the basis of the numerical results.Resistance measurement was carried out using samples of normal RBCs and rigidified (Ca(2+)-A23186 treated) RBCs.Visualization measurement of the cells' behavior was carried out using a high-speed camera, and the results were compared with those obtained above to evaluate the performance of the sensor.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering and Science, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan. tatsumi@me.kyoto-u.ac.jp

ABSTRACT
A microsensor that can continuously measure the deformability of a single red blood cell (RBC) in its microchannels using microelectrodes is described in this paper. The time series of the electric resistance is measured using an AC current vs. voltage method as the RBC passes between counter-electrode-type micro-membrane sensors attached to the bottom wall of the microchannel. The RBC is deformed by the shear flow created in the microchannel; the degree of deformation depends on the elastic modulus of the RBC. The resistance distribution, which is unique to the shape of the RBC, is analyzed to obtain the deformability of each cell. First, a numerical simulation of the electric field around the electrodes and RBC is carried out to evaluate the influences of the RBC height position, channel height, distance between the electrodes, electrode width, and RBC shape on the sensor sensitivity. Then, a microsensor was designed and fabricated on the basis of the numerical results. Resistance measurement was carried out using samples of normal RBCs and rigidified (Ca(2+)-A23186 treated) RBCs. Visualization measurement of the cells' behavior was carried out using a high-speed camera, and the results were compared with those obtained above to evaluate the performance of the sensor.

Show MeSH