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, 13 (1), 014103
eCollection

Biomimetic Pulsatile Flows Through Flexible Microfluidic Conduits

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Biomimetic Pulsatile Flows Through Flexible Microfluidic Conduits

Kiran Raj M et al. Biomicrofluidics.

Abstract

We bring out unique aspects of the pulsatile flow of a blood analog fluid (Xanthan gum solution) in a biomimetic microfluidic channel. Pressure waveforms that mimic biologically consistent pulsations are applied on physiologically relevant cylindrical microchannels fabricated using polydimethylsiloxane. The in vivo features of the relevant waveforms like peak amplitude and dicrotic notch are reproduced in vitro. The deformation profiles exhibit viscoelastic behavior toward the end of each cycle. Further, the time-varying velocity profiles are critically analyzed. The local hydrodynamics within the microchannel is found to be more significantly affected by pressure waveform rather than the actual wall deformation and the velocity profile. These results are likely to bear far-reaching implications for assessing micro-circulatory dynamics in lab on a chip based microfluidic platforms that to a large extent replicate physiologically relevant conditions.

Figures

FIG. 1.
FIG. 1.
(a) Experimental setup indicating the solenoid valve actuation using a function generator, the pressure measurement system, and the DAQ. A cross-sectional schematic in the transverse plane is also shown. (b) Typical waveforms of the applied voltage to the function generator, pressure gradient, and the deformation of the channel at the center.
FIG. 2.
FIG. 2.
Time-varying pressure drop for a base flow rate of Qbase= 500 μl/min for (a) 1 Hz and (b) 2 Hz for CH10 and CH30 for de-ionized water. CH10 is the non-deformable, and CH30 is the deformable microchannel. (DI) and Xanthan Gum (XG). The waveform is plotted after the system attained a steady state. The inset shows the region near the dicrotic notch.
FIG. 3.
FIG. 3.
Mean and peak pressure drop for a base flow rate of Qbase = 500 μl/min for (a) ω = 1 Hz and (b) ω = 2 Hz for CH10 and CH30 for DI and XG. Error bars denote the standard deviations of measurements from three separate microchannels.
FIG. 4.
FIG. 4.
(a) Time-varying deformation profile of the wall for CH30 at the ROI (z = 13.5 cm). (b) Mean and peak values of deformation for various cases.
FIG. 5.
FIG. 5.
Time constants (τ) associated with both pressure and deformation profiles.
FIG. 6.
FIG. 6.
Theoretical Womersley profiles and experimental values at different time intervals in a single cycle (with time period T) for various cases at ω = 1 Hz and ω = 2 Hz. Normalized phase is given in brackets. Error bars represent average over 10 cycles (a) T/4 for ω = 1 Hz (π/2), (b) T/4 for ω = 2 Hz (π), (c) T/2 for ω = 1 Hz (π), and (d) T/2 for ω = 2 Hz (2π).

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