When
an
interface
exists
between
a
liquid
and
a
solid,
the
angle
between
the
surface
of
the
liquid
and
the
outline
of
the
contact
surface
is
described
as
the
contact
angle.
The
size
of
the
contact
angle
is
the
metrics
of
the
hydrophobicity
of
the
surface.
The
prediction
of
the
contact
angle
has
significant
effect
on
the
design
of
hydrophobic
surface
and
improvement
of
hydrophobicity.
In
this
paper,
a
prediction
model
for
contact
angle
has
been
proposed
based
on
minimum
Gibbs
free
energy.
It
considers
the
effects
of
unilateral
force
and
area
constraints
of
the
droplets.
The
effect
of
micro-structural
parameters
on
contact
angle
has
also
been
investigated.
Micro-milling
experiments
have
been
conducted
to
fabricate
the
hydrophobic
surface
in
order
to
validate
the
predictive
capability
of
the
contact
angle
model.
Results
revealed
that
the
established
prediction
model
could
estimate
the
contact
angle
of
hydrophobic
surface.
The
contact
angle
could
be
increased
by
increasing
concave
width
or
reducing
convex.
The
outcome
of
this
research
will
lead
to
new
methodologies
for
preparing
hydrophobic
surfaces
with
micro-machining
technology.