Biomedical Engineering Reference
In-Depth Information
Flow
a
Obstacle
b
c
20 µm
1 2 3
1 2 3
1 2 3
1 2 3
0.4 µm
1.0 µm
Flow
x
1 2 3
1 2 3
1 2 3
1 2 3
y
Small particles
Large particles
FIGURE 4.7
Deterministic. lateral. displacement.. (From. Nicole. Pamme,. “Continuous. low. separa-
tions.in.microluidic.devices,”.
Lab Chip
.7,.1644-1659,.2007;.and.Lotien.Richard.Huang,.Edward.
C..Cox,.Robert.H..Austin,.and.James.C..Sturm,.“Continuous.particle.separation.through.determin-
istic.lateral.displacement,”.
Science
.304,.987,.2004..Reproduced.with.permission.from.The.Royal.
Society.of.Chemistry..Figure.contributed.by.Nicole.Pamme.)
a
Ogston sieving
d
λ DNA-Hind III digest
injection (6 fragments ranging
2,027 bp-23,130 bp)
E
x
E
y
(-)
(+)
E
x
= 185 V/cm
E
y
= 100 V/cm
E
x
Debye layer
b
Entropic trapping
E
x
E
y
(-)
(+)
E
x
1 mm
c
Electrostatic sieving
Pillar
Shallow
Deep
E
x
x
E
y
y
(-)
(+)
Sample
collection
E
x
FIGURE 4.8
Anisotropic.sieving..(From.Nicole.Pamme,.“Continuous.low.separations.in.microlu-
idic.devices,”.
Lab Chip
.7,.1644-1659,.2007;.and.Jianping.Fu,.Reto.B..Schoch,.Anna.L..Stevens,.
Steven.R..Tannenbaum,.and.Jongyoon.Han,.“A.patterned.anisotropic.nanoluidic.sieving.structure.
for.continuous-low.separation.of.DNA.and.proteins,”.
Nat. Nanotech.
.2,.121,.2007..Reproduced.
with.permission.from.The.Royal.Society.of.Chemistry..Figure.contributed.by.Nicole.Pamme.)
4.5 Microluidic Immunoassays
Molecular biology has given us a new set of nucleic acid-based assays that are unsurpassed for
measuring small quantities of nucleic acids themselves. However, they are no use for measuring
most other types of chemicals. One of the most powerful and versatile biomedical diagnostic
tools, the immunoassay, is used today to monitor almost everything else: the levels of drugs and
