Limits...
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
Relationship of ΔR0 and δ with the deformation index DI (experiment).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3472844&req=5

f7-sensors-12-10566: Relationship of ΔR0 and δ with the deformation index DI (experiment).

Mentions: Figure 7 shows the relationship of the maximum resistance difference ΔR0 and the half bandwidth of the ΔRx/ΔR0 distribution, δ, versus DI. These values were obtained from the electrical and visualization measurements. It should be noted that a linear correction was made for the ΔR0 and δ in consideration of the spanwise position of the RBC when it passed between the electrodes. That is, as was also observed in the photographs shown in Figure 6, the spanwise position of the RBC varied in the range of −2.5 ≤ yRBC ≤ 2.5. Although the electrodes and the RBC had a symmetric shape, ΔR0 and δ increased and decreased slightly depending on the spanwise position of the RBC. It is believed that the electrodes were not absolutely symmetric due to their platinum black plating, so that an asymmetric electric field was generated between them. To account for this effect, the linear components in each distribution were subtracted from each value. The results shown in Figure 7 reflect these adjustments that were made.


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)

Relationship of ΔR0 and δ with the deformation index DI (experiment).
© Copyright Policy
Related In: Results  -  Collection

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

f7-sensors-12-10566: Relationship of ΔR0 and δ with the deformation index DI (experiment).
Mentions: Figure 7 shows the relationship of the maximum resistance difference ΔR0 and the half bandwidth of the ΔRx/ΔR0 distribution, δ, versus DI. These values were obtained from the electrical and visualization measurements. It should be noted that a linear correction was made for the ΔR0 and δ in consideration of the spanwise position of the RBC when it passed between the electrodes. That is, as was also observed in the photographs shown in Figure 6, the spanwise position of the RBC varied in the range of −2.5 ≤ yRBC ≤ 2.5. Although the electrodes and the RBC had a symmetric shape, ΔR0 and δ increased and decreased slightly depending on the spanwise position of the RBC. It is believed that the electrodes were not absolutely symmetric due to their platinum black plating, so that an asymmetric electric field was generated between them. To account for this effect, the linear components in each distribution were subtracted from each value. The results shown in Figure 7 reflect these adjustments that were made.

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