Supplementary Material
“Inducing 3D vortical flow patterns with 2D asymmetric actuation of
artificial cilia for high performance active micromixing”
by Chia-Yuan Chen*, Cheng-Yi Lin, and
Ya-Ting Hu
Department of Mechanical Engineering, National Cheng Kung University
*To whom correspondence should be addressed.
* E-mail:chiayuac@mail.ncku.edu.tw; Tel: +886-6-2757575-62169.
The
electronic
supplementary
material
includes
the
following:
(1)
Motion
characterizations of the fabricated artificial cilia, (2) validation of µPIV method, and (3)
validation of the 3D numerical modeling method.
(1) Motion characterizations of the fabricated artificial cilia: The schematic layout of the
magnetic coil system and the orientation of each artificial cilium are illustrated in Fig.
S1(a). The orientation change of the artificial cilium with the direction change of the
applied magnetic field is provided in Fig. S1(b). A linear relationship with R 2 over 0.99
was calculated. This result demonstrated that an accurate motion control of artificial
cilium can be achieved through the control of the applied magnetic field using the
presented magnetic coil system. In addition, the change of tip displacement of the
artificial cilium under the influence of the applied magnetic field is presented in Fig.
S1(c). The beating area of artificial cilium can be controlled precisely through the control
of the applied voltage using the magnetic coil system as the tip displacement increases
linearly with the increase of the applied magnetic field. The relation of rotational speed
with the rotational radius of the artificial cilium under the influence of magnetic field is
shown in Fig. S1(d). The rotational radius reduced to an asymptotic value (approximately
40 µm) when the rotational speed is faster than 30 Hz.
Fig. S1 Characterizations of the magnetically actuated artificial cilia. (a) Schematic
illustration of the magnetic actuation system and the micromixer with artificial cilia
integrated. (b) Orientation change of the artificial cilium in response to the change of the
applied magnetic field. (c) Displacement of the artificial cilium linearly proportional to
the applied voltage (Chen et al. 2013). (d) Relationship between the rotational speed and
radius of the artificial cilium (Chen et al. 2013).
(2) Validation of the µPIV method: The measured and calculated instantaneous flow
fields by µPIV were compared with the theoretical solutions to provide information on
the accuracy of the presented flow quantification technique. The theoretical solutions
were derived from previous literature (Lima et al. 2009). The flow field comparison was
conducted at z = 300 µm from the bottom wall (same as the artificial cilium height). Flow
rate was set at 2 µL/min. Acquired µPIV velocity profiles of three locations along the
microchannel length were averaged. Error bars indicate one standard deviation value of
the averaged velocity profile.
Fig. S2 Comparison between the velocity profiles acquired by µPIV and the theoretical
solutions.
(3) Validation of the 3D numerical modeling method: Induced vortical structures
acquired by µPIV were compared with numerical results under identical initial and
boundary conditions. The results showed that the vorticity distribution obtained by the
3D numerical modeling method matched well with that by the µPIV method. This
agreement can serve as a good basis of accuracy for the further applications of this
numerical method in examining out-of-plane velocity fields, which cannot be achieved
using the presented µPIV method.
Fig. S3 Comparison between the vorticity distribution obtained by µPIV (first row) and
that by 3D numerical modeling (second row) at four distinct time points. Dark arrows
represent in-plane velocity vectors.
References:
Chen CY, Chen CY, Lin CY, Hu YT (2013) Magnetically actuated artificial cilia for
optimum mixing performance in microfluidics. Lab Chip 13(14):2834–2839
Lima R, Ishikawa T, Imai Y, Takeda M, Wada S, Yamaguchi T (2009) Measurement of
individual red blood cell motions under high hematocrit conditions using a confocal
micro-PTV system. Ann Biomed Eng 37(8):1546-1559