<s>
Electrowetting	B-General_Concept
is	O
the	O
modification	O
of	O
the	O
wetting	O
properties	O
of	O
a	O
surface	O
(	O
which	O
is	O
typically	O
hydrophobic	O
)	O
with	O
an	O
applied	O
electric	O
field	O
.	O
</s>
<s>
The	O
electrowetting	B-General_Concept
of	O
mercury	O
and	O
other	O
liquids	O
on	O
variably	O
charged	O
surfaces	O
was	O
probably	O
first	O
explained	O
by	O
Gabriel	O
Lippmann	O
in	O
1875	O
and	O
was	O
certainly	O
observed	O
much	O
earlier	O
.	O
</s>
<s>
The	O
term	O
electrowetting	B-General_Concept
was	O
first	O
introduced	O
in	O
1981	O
by	O
G	O
.	O
Beni	O
and	O
S	O
.	O
Hackwood	O
to	O
describe	O
an	O
effect	O
proposed	O
for	O
designing	O
a	O
new	O
type	O
of	O
display	O
device	O
for	O
which	O
they	O
received	O
a	O
patent	O
.	O
</s>
<s>
Silver	O
at	O
the	O
NIH	O
,	O
EWOD-based	O
electrowetting	B-General_Concept
was	O
disclosed	O
for	O
single	O
and	O
immiscible	O
fluids	O
to	O
move	O
,	O
separate	O
,	O
hold	O
and	O
seal	O
arrays	O
of	O
digital	O
PCR	O
sub-samples	O
.	O
</s>
<s>
Electrowetting	B-General_Concept
using	O
an	O
insulating	O
layer	O
on	O
top	O
of	O
a	O
bare	O
electrode	O
was	O
later	O
studied	O
by	O
Bruno	O
Berge	O
in	O
1993	O
.	O
</s>
<s>
Electrowetting	B-General_Concept
on	O
this	O
dielectric-coated	O
surface	O
is	O
called	O
electrowetting-on-dielectric	O
(	O
EWOD	B-General_Concept
)	O
to	O
distinguish	O
it	O
from	O
the	O
conventional	O
electrowetting	B-General_Concept
on	O
the	O
bare	O
electrode	O
.	O
</s>
<s>
Electrowetting	B-General_Concept
can	O
be	O
demonstrated	O
by	O
replacing	O
the	O
metal	O
electrode	O
in	O
the	O
EWOD	B-General_Concept
system	O
by	O
a	O
semiconductor	O
.	O
</s>
<s>
Electrowetting	B-General_Concept
is	O
also	O
observed	O
when	O
a	O
reverse	O
bias	O
is	O
applied	O
to	O
a	O
conducting	O
droplet	O
(	O
e.g.	O
</s>
<s>
silicon	O
)	O
to	O
form	O
a	O
Schottky	O
contact	O
in	O
a	O
Schottky	O
diode	O
electrical	O
circuit	O
configuration	O
–	O
this	O
effect	O
has	O
been	O
termed	O
‘	O
Schottky	O
electrowetting’	O
.	O
</s>
<s>
Microfluidic	O
manipulation	O
of	O
liquids	O
by	O
electrowetting	B-General_Concept
was	O
demonstrated	O
first	O
with	O
mercury	O
droplets	O
in	O
water	O
and	O
later	O
with	O
water	O
in	O
air	O
and	O
water	O
in	O
oil	O
.	O
</s>
<s>
Discretization	O
by	O
electrowetting-on-dielectric	O
(	O
EWOD	B-General_Concept
)	O
was	O
first	O
demonstrated	O
by	O
Cho	O
,	O
Moon	O
and	O
Kim	O
.	O
</s>
<s>
The	O
electrowetting	B-General_Concept
effect	O
has	O
been	O
defined	O
as	O
"	O
the	O
change	O
in	O
solid-electrolyte	O
contact	O
angle	O
due	O
to	O
an	O
applied	O
potential	O
difference	O
between	O
the	O
solid	O
and	O
the	O
electrolyte	O
"	O
.	O
</s>
<s>
The	O
phenomenon	O
of	O
electrowetting	B-General_Concept
can	O
be	O
understood	O
in	O
terms	O
of	O
the	O
forces	O
that	O
result	O
from	O
the	O
applied	O
electric	O
field	O
.	O
</s>
<s>
Alternatively	O
,	O
electrowetting	B-General_Concept
can	O
be	O
viewed	O
from	O
a	O
thermodynamic	O
perspective	O
.	O
</s>
<s>
The	O
simplest	O
derivation	O
of	O
electrowetting	B-General_Concept
behavior	O
is	O
given	O
by	O
considering	O
its	O
thermodynamic	O
model	O
.	O
</s>
<s>
While	O
it	O
is	O
possible	O
to	O
obtain	O
a	O
detailed	O
numerical	O
model	O
of	O
electrowetting	B-General_Concept
by	O
considering	O
the	O
precise	O
shape	O
of	O
the	O
electrical	O
fringing	O
field	O
and	O
how	O
it	O
affects	O
the	O
local	O
droplet	O
curvature	O
,	O
such	O
solutions	O
are	O
mathematically	O
and	O
computationally	O
complex	O
.	O
</s>
<s>
So	O
,	O
a	O
complete	O
explanation	O
of	O
electrowetting	B-General_Concept
is	O
unquantified	O
,	O
but	O
it	O
should	O
not	O
be	O
surprising	O
that	O
these	O
limits	O
exist	O
.	O
</s>
<s>
that	O
contact	O
angle	O
saturation	O
can	O
be	O
explained	O
as	O
a	O
universal	O
effect	O
-	O
regardless	O
of	O
materials	O
used	O
–	O
if	O
electrowetting	B-General_Concept
is	O
observed	O
as	O
a	O
global	O
phenomenon	O
affected	O
by	O
the	O
detailed	O
geometry	O
of	O
the	O
system	O
.	O
</s>
<s>
Within	O
this	O
framework	O
it	O
is	O
predicted	O
that	O
reversed	O
electrowetting	B-General_Concept
is	O
also	O
possible	O
(	O
contact	O
angle	O
grows	O
with	O
the	O
voltage	O
)	O
.	O
</s>
<s>
Reverse	O
electrowetting	B-General_Concept
can	O
be	O
used	O
to	O
harvest	O
energy	O
via	O
a	O
mechanical-to-electrical	O
engineering	O
scheme	O
.	O
</s>
<s>
Another	O
electrowetting	B-General_Concept
configuration	O
is	O
electrowetting	B-General_Concept
on	O
liquid-infused	O
film	O
.	O
</s>
<s>
Taking	O
advantage	O
of	O
the	O
negligible	O
contact	O
line	O
pinning	O
at	O
the	O
liquid-liquid	O
interface	O
,	O
the	O
droplet	O
response	O
in	O
EWOLF	O
can	O
be	O
electrically	O
addressed	O
with	O
enhanced	O
degree	O
of	O
switchability	O
and	O
reversibility	O
compared	O
to	O
the	O
conventional	O
EWOD	B-General_Concept
.	O
</s>
<s>
Moreover	O
,	O
the	O
infiltration	O
of	O
liquid	O
lubricant	O
phase	O
in	O
the	O
porous	O
membrane	O
also	O
efficiently	O
enhances	O
the	O
viscous	O
energy	O
dissipation	O
,	O
suppressing	O
the	O
droplet	O
oscillation	O
and	O
leading	O
to	O
fast	O
response	O
without	O
sacrificing	O
the	O
desired	O
electrowetting	B-General_Concept
reversibility	O
.	O
</s>
<s>
Optoelectrowetting	O
,	O
and	O
photoelectrowetting	O
are	O
both	O
optically-induced	O
electrowetting	B-General_Concept
effects	O
.	O
</s>
<s>
Optoelectrowetting	O
involves	O
the	O
use	O
of	O
a	O
photoconductor	O
whereas	O
photoelectrowetting	O
use	O
a	O
photocapacitance	O
and	O
can	O
be	O
observed	O
if	O
the	O
conductor	O
in	O
the	O
liquid/insulator/conductor	O
stack	O
used	O
for	O
electrowetting	B-General_Concept
is	O
replaced	O
by	O
a	O
semiconductor	O
.	O
</s>
<s>
For	O
reasons	O
that	O
are	O
still	O
under	O
investigation	O
,	O
only	O
a	O
limited	O
set	O
of	O
surfaces	O
exhibit	O
the	O
theoretically	O
predicted	O
electrowetting	B-General_Concept
behavior	O
.	O
</s>
<s>
For	O
example	O
,	O
amorphous	O
fluoropolymers	O
are	O
widely	O
used	O
electrowetting	B-General_Concept
coating	O
materials	O
,	O
and	O
it	O
has	O
been	O
found	O
that	O
the	O
behavior	O
of	O
these	O
fluoropolymers	O
can	O
be	O
enhanced	O
by	O
the	O
appropriate	O
surface	O
patterning	O
.	O
</s>
<s>
These	O
fluoropolymers	O
coat	O
the	O
necessary	O
conductive	O
electrode	O
,	O
typically	O
made	O
of	O
aluminum	O
foil	O
or	O
indium	O
tin	O
oxide	O
(	O
ITO	O
)	O
,	O
to	O
create	O
the	O
desired	O
electrowetting	B-General_Concept
properties	O
.	O
</s>
<s>
Electrowetting	B-General_Concept
is	O
now	O
used	O
in	O
a	O
wide	O
range	O
of	O
from	O
modular	O
to	O
adjustable	O
lenses	O
,	O
electronic	O
displays	O
(	O
e-paper	O
)	O
,	O
electronic	O
outdoor	O
displays	O
and	O
switches	O
for	O
optical	O
fibers	O
.	O
</s>
<s>
Electrowetting	B-General_Concept
has	O
recently	O
been	O
evoked	O
for	O
manipulating	O
soft	O
matter	O
particularly	O
,	O
suppressing	O
coffee	O
stain	O
effect	O
.	O
</s>
<s>
Furthermore	O
,	O
filters	O
with	O
electrowetting	B-General_Concept
functionality	O
has	O
been	O
suggested	O
for	O
cleaning	O
oil	O
spills	O
and	O
separating	O
oil-water	O
mixtures	O
.	O
</s>
<s>
An	O
international	O
meeting	O
for	O
electrowetting	B-General_Concept
is	O
held	O
every	O
two	O
years	O
.	O
</s>
<s>
The	O
previous	O
hosts	O
of	O
the	O
electrowetting	B-General_Concept
meeting	O
are	O
:	O
Mons	O
(	O
1999	O
)	O
,	O
Eindhoven	O
(	O
2000	O
)	O
,	O
Grenoble	O
(	O
2002	O
)	O
,	O
Blaubeuren	O
(	O
2004	O
)	O
,	O
Rochester	O
(	O
2006	O
)	O
,	O
Los	O
Angeles	O
(	O
2008	O
)	O
,	O
Pohang	O
(	O
2010	O
)	O
,	O
Athens	O
(	O
2012	O
)	O
,	O
Cincinnati	O
(	O
2014	O
)	O
,	O
Taipei	O
(	O
2016	O
)	O
.	O
</s>
