Biomedical Engineering Reference
In-Depth Information
TABLe 17.2
Dielectric.Properties.of.Different.Cells.and.the.PBS.Buffer.Solution.Used.in.DEP.Simulation
Inner Compartment
Membrane
Cell Wall
Radius
(
μ
m)
Thickness
(nm)
Thickness
(nm)
Particle
ɛ
σ
(S/m)
ɛ
σ
(S/m)
ɛ
σ
(S/m)
Latex.
beads
0.01-20
2.5
2e−4
—
—
—
—
—
—
Yeast
4.8
60
0.2
6
2.5e−7
8
60
0.014
∼200
E. coli
1.0
60
0.1
10
5e−8
5
60
0.5
20
HSV-1.
virus
0.25
70
0.008
10
σ
p
.=.3.5.nS
—
—
—
HL-60
6.25
75
0.75
1.6.μF/cm
2
0.22.S/cm
2
1.0
—
—
—
PBS
—
78
1.5
—
—
—
—
—
—
Source:
. With. kind. permission. from. Springer. Science+Business. Media:.
BioMEMS Biomed. Nanotechnol
.,.
Dielectrophoretic. traps. for. cell. manipulation,. 4,. 159-186,. Voldman,. J.,. Springer,. E.D.,. Ferrari,. M.S.,.
Bashir,.R.,.and.Wereley,.S.,.Copyright.2007.)
Note:
. The.data.from.original.table.is.taken.from.Zhou.et.al..(1996,.1998);.Huang.et.al..(1997);.Hughes.and.Morgan.
(1998);.Suehiro.et.al..(2003).
simpliication. of. the. effective. permittivity. of. the. particle. is. schematically. presented. in.
Figure.17.3b.and.is.given.by
(
)
R R
3
∗
∗
∗
∗
(
/[
−
δ
]
)
+
2
(
ε
−
ε
)/(
ε
+
2
ε
)
cyt
mem
cyt
mem
∗
∗
ε
=
ε
.
(17.11)
p
mem
(
)
3
∗
∗
∗
∗
(
R R
/[
−
δ
])
−
(
ε
−
ε
)/(
ε
+
2
ε
)
cyt
mem
cyt
mem
.
where
ε
mem
∗
. and. ε
cy
∗
. are. the. complex. permittivity. of. the. plasma. membrane. and. the. cell. cyto-
plasm,.respectively
R
.is.the.outer.radius.of.the.cell
δ.is.the.plasma.membrane.thickness
The. values. of. these. parameters. used. in. DEP. simulations. are. listed. in. Table. 17.2.. Other.
structural.heterogeneity.of.cells,.such.as.a.nonspherical.shape.(e.g.,.
E. coli
.and.red.blood.
cells). and. inhomogeneous. plasma. membranes,. and/or. inner. compartments. can. also.
utilize.similar.approximations.(Irimajiri.et.al..1979;.Kakutani.et.al..1993;.Sukhorukov.et.al..
2001)..The.inluence.from.the.surface.conductivity.of.particles.and.the.associated.electrical.
double-layer.change.during.polarization.has.also.been.estimated.with.more.sophisticated.
models.(Lyklema.et.al..1995;.Zhou.et.al..2005)..A.typical.frequency.spectrum.of.the.DEP.
force.based.on.a.multishell.cell.model.is.shown.in.Figure.17.3c.and.the.simulation.results.
of.the.frequency.spectrum.for.Re[
K
*
].on.various.types.of.cells.are.given.in.Figure.17.3d.
17.2.2.3 Electric Field Gradient
From.Equation.17.5,.the.electric.ield.strength.and.its.gradient.greatly.affect.the.magnitude.
of. the. DEP. force. on. particles.. Therefore,. the. coniguration. of. electrodes. (e.g.,. their.
geometry.and.relative.positions).is.critical.to.generate.an.appropriate.nonuniform.electric.
ield. gradient. and. to. conduct. eficient. DEP. manipulation.. The. simplest. coniguration.
is. the. pin-wire. pair. electrode. design. (sometimes. also. called. the. pin-plane. pair). used. in.
