Supporting Information for
Microfluidic Pycnometer for in Situ Analysis of Fluids
in Microchannels
Joo H. Kang, Bumjun Kim, and Je-Kyun Park*
Department of Bio and Brain Engineering, College of Life Science and Bioengineering, KAIST,
335 Gwahangno, Yuseong-gu, Daejeon 305-701, Republic of Korea
* To whom correspondence should be addressed. E-mail: jekyun@kaist.ac.kr. Phone: +82-42-3504315. Fax: +82-42-350-4310.
Table of Contents:
Figures 1~3
1
„
Initial status of the experiments
The crucial requirement for valuable experiments is that incoming laminar flows from three inlets
should stay in a steady-state because pyklinophoresis (PKP) is subject to the solution density. To
address this issue, we have to check the interfacial line between two different solutions before obtaining
the results.
Figure 1. A picture shows an intersection of the microfluidic device. The asymmetric interfacial line
(left side) is observed only between solution A and C, not between B and C because solution B and C
are the same while solution A and C have difference in solution density. If the interfacial line is
observed on both side (left and right), solutions should flow out for a while because this implies that the
fluidic concentration is not in equilibrium.
2
„
Attached movie caption
Fluid interface
Low density
High density
A spherical particle
Figure 2. A movie file, showing particle migration driven by PKP, is attached in the Supporting
Information. A particle submerged in solutions moves from one side (high density) to the other side
(low density). It also presents a rotating motion of the particle during the migration that is driven by
asymmetric buoyancy as described in the manuscript. This movie shows only qualitative behaviors of
the particle during PKP because the dimensions in this scheme are not to scale.
3
Reorientation of fluid interface
z
x (a) 100 μm
y
y=1.0 mm
(b) 500 μm
y=2.0 mm
y=3.0 mm
20 μm
500 μm
„
y=1.0 mm
y=2.0 mm
y=3.0 mm
y=11.0 mm
Figure 3. Reorientation of fluid interface of the device used in this research. Part a is negligible
compared to the microchannel geometry of 1.0 (height/width). (b) At the boundary conditions, two
fluids with different density (deionized water and ethanol) were injected into the channel at a flow rate
of 0.2 m/s. Figures are not to scale. Reorientation of the fluid interface was proved by the CFD-ACE+
solver (ESI, Huntsville, AL).
4