48
A. Hu et al.
Fig. 1.34 Dielectrical forces acting on a particle in an electrical field
as
F DEP = πr
2 lε m k(ω)
E r · ∇
E r
= πr
2 lε m k(ω)∇|E r |
(1.4.8)
k(ω) = Re
ε
∗
n − ε
∗
m
ε ∗
m
(1.4.9)
ε
∗
= ε − i
σ
ω
(1.4.10)
where ε
∗
n is the complex permittivity of particle and ε
∗
m is for medium, ε is the
dielectric constant, σ is electrical conductivity and ω is the field frequency, E r is the
root mean square of the external excitation field E. For a positive DEP, the particle
will move toward to high field region and the negative DEP drives the particle to
move away from high field region. In our recent works [6], both Cu nanowires and
T e nanowires are aligned by DEP at a certain frequency range and voltage.
ACEO is a phenomenon of induced-charge electro-osmosis of liquid, where the
fluidic flow is generated by the action of an electric field on its induced ion diffusion near a polarizable surface. The ion‘s attachment and accumulation to the electrode surface will cause the capacitance change. Thus, ACEO is extensively used for
sensing in liquid [158].
Since ACEO is caused by the counter-ions migration with or against the electric field, which produces fluidic motion due to fluidic viscosity, it is expected that
the fluidic flow velocity will keep changing due to the ion migration. At a low
A. Hu et al.
Fig. 1.34 Dielectrical forces acting on a particle in an electrical field
as
F DEP = πr
2 lε m k(ω)
E r · ∇
E r
= πr
2 lε m k(ω)∇|E r |
(1.4.8)
k(ω) = Re
ε
∗
n − ε
∗
m
ε ∗
m
(1.4.9)
ε
∗
= ε − i
σ
ω
(1.4.10)
where ε
∗
n is the complex permittivity of particle and ε
∗
m is for medium, ε is the
dielectric constant, σ is electrical conductivity and ω is the field frequency, E r is the
root mean square of the external excitation field E. For a positive DEP, the particle
will move toward to high field region and the negative DEP drives the particle to
move away from high field region. In our recent works [6], both Cu nanowires and
T e nanowires are aligned by DEP at a certain frequency range and voltage.
ACEO is a phenomenon of induced-charge electro-osmosis of liquid, where the
fluidic flow is generated by the action of an electric field on its induced ion diffusion near a polarizable surface. The ion‘s attachment and accumulation to the electrode surface will cause the capacitance change. Thus, ACEO is extensively used for
sensing in liquid [158].
Since ACEO is caused by the counter-ions migration with or against the electric field, which produces fluidic motion due to fluidic viscosity, it is expected that
the fluidic flow velocity will keep changing due to the ion migration. At a low