TY - JOUR
T1 - Evanescent wave-based particle tracking velocimetry for nanochannel flows
AU - Kazoe, Yutaka
AU - Iseki, Keizo
AU - Mawatari, Kazuma
AU - Kitamori, Takehiko
PY - 2013/11/19
Y1 - 2013/11/19
N2 - Understanding fluid flows in 10-1000 nm space, which we call extended nanospace, is important for novel nanofluidic devices in analytical chemistry. This study therefore developed a particle tracking velocimetry for measuring velocity distribution in nanochannel flows, by using the evanescent wave illumination. 64 nm fluorescent nanoparticles were used as flow tracer. The particle position was determined from fluorescent intensity by the evanescent wave field, with a spatial resolution smaller than light wavelengths. The time resolution of 260 μs was achieved to make error by the Brownian diffusion of the tracer small to be neglected. An image processing by multitime particle tracking was established to detect the tracer nanoparticles of weak fluorescent intensity. Though the measurement region was affected by nonuniform particle distribution with the electrostatic interactions, pressure-driven flows of water in a nanochannel of 50 μm width and 410 nm depth were successfully measured. The results of the velocity distribution in the depth-wise direction approximately showed agreement with the fluid dynamics with the bulk liquid properties from the macroscopic view, however, suggested slip velocities even in the hydrophilic channel. We suggest a possibility of appearance of molecular behavior in the fluid near the wall within 10 nm-order scale.
AB - Understanding fluid flows in 10-1000 nm space, which we call extended nanospace, is important for novel nanofluidic devices in analytical chemistry. This study therefore developed a particle tracking velocimetry for measuring velocity distribution in nanochannel flows, by using the evanescent wave illumination. 64 nm fluorescent nanoparticles were used as flow tracer. The particle position was determined from fluorescent intensity by the evanescent wave field, with a spatial resolution smaller than light wavelengths. The time resolution of 260 μs was achieved to make error by the Brownian diffusion of the tracer small to be neglected. An image processing by multitime particle tracking was established to detect the tracer nanoparticles of weak fluorescent intensity. Though the measurement region was affected by nonuniform particle distribution with the electrostatic interactions, pressure-driven flows of water in a nanochannel of 50 μm width and 410 nm depth were successfully measured. The results of the velocity distribution in the depth-wise direction approximately showed agreement with the fluid dynamics with the bulk liquid properties from the macroscopic view, however, suggested slip velocities even in the hydrophilic channel. We suggest a possibility of appearance of molecular behavior in the fluid near the wall within 10 nm-order scale.
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U2 - 10.1021/ac401964h
DO - 10.1021/ac401964h
M3 - Article
C2 - 24143898
AN - SCOPUS:84888382985
VL - 85
SP - 10780
EP - 10786
JO - Industrial And Engineering Chemistry Analytical Edition
JF - Industrial And Engineering Chemistry Analytical Edition
SN - 0003-2700
IS - 22
ER -