Biomedical Engineering Reference
In-Depth Information
(a)
c=c
o
Attractant/repellent
input
Chemical source
channel
Outlet
c=0
Agarose
gel
(b)
Source
Center
Sink
6000
4000
Cell
input
Buffer
input
Outlet
Chemical sink
channel
Cell
2000
Outlet
0
0
500 1000 1500 2000
Distance across channel (µm)
FIGURE 3.87
Gradient. generator. made. in. agarose.. (From. Shing-Yi. Cheng,. Steven. Heilman,. Max.
Wasserman,.Shivaun.Archer,.Michael.L..Shuler,.and.Mingming.Wu,.“A.hydrogel-based.microluidic.
device.for.the.studies.of.directed.cell.migration,”.
Lab Chip
.7,.763-769,.2007..Reproduced.with.
permission.from.The.Royal.Society.of.Chemistry.)
in approximately 15 to 30 minutes as long as the sink/source stay constant. Importantly, varying
the design of the gradient region (
Figure 3.90c
and
d
) can be used to change the gradient's shape
(
Figure 3.90e
through
g
) and gradients through dissimilar gels are also possible (
Figure 3.90h
).
In most chemotaxis experiments, the cells are presented with a “control” condition at some
point—a condition that does not contain the chemotactic factor, to verify that cells do not respond
Gradient plane
Directional
derivative
(a)
(b)
θ
(x
0
, y
0
)
s
G
0
θ
3π/2
2π
0
π/2 π
y
-
G
0
x
Reservoirs
(c)
y
x
100 µm
Fluidic
channel
(d)
Reservoir
Reservoir
PDMS
100 µm
PDMS
Fluidic channel
Hydrogel
FIGURE 3.88
Arbitrary.gradient.generator.based.on.diffusion.across.a.hydrogel.slab..(From.Hongkai.
Wu,.Bo.Huang,.and.Richard.N..Zare,.“Generation.of.complex,.static.solution.gradients.in.micro-
luidic.channels,”.
J. Am. Chem. Soc.
.128,.4194-4195,.2006..Reprinted.with.permission.of.the.
American.Chemical.Society.)
