<s>
Patterning	B-Algorithm
by	I-Algorithm
Etching	I-Algorithm
at	I-Algorithm
the	I-Algorithm
nanoscale	I-Algorithm
(	O
PENs	O
)	O
is	O
a	O
soft	B-Algorithm
lithographic	I-Algorithm
technique	O
in	O
which	O
the	O
bonds	O
in	O
the	O
polydimethylsiloxane	O
(	O
PDMS	O
)	O
matrix	O
are	O
broken	O
to	O
controlably	O
etch	O
PDMS	O
(	O
i.e.	O
</s>
<s>
dissolve	O
)	O
at	O
a	O
slow	O
rate	O
along	O
the	O
outside	O
of	O
a	O
PDMS	O
channel	O
formed	O
with	O
a	O
patterned	O
PDMS	B-Algorithm
stamp	I-Algorithm
applied	O
to	O
a	O
surface	O
.	O
</s>
<s>
PDMS	O
contains	O
polymer	O
chains	O
of	O
silicon-oxygen	O
bonds	O
,	O
these	O
bonds	O
can	O
be	O
broken	O
by	O
fluoride	O
containing	O
species	O
,	O
in	O
the	O
same	O
way	O
that	O
silicon	B-Architecture
wafers	I-Architecture
are	O
prepared	O
by	O
etching	O
with	O
hydrofluoric	O
acid	O
,	O
ammonium	O
fluoride	O
and	O
related	O
compounds	O
.	O
</s>
<s>
By	O
placing	O
a	O
PDMS	B-Algorithm
stamp	I-Algorithm
that	O
contains	O
a	O
channel	O
that	O
can	O
be	O
externally	O
filled	O
on	O
to	O
a	O
surface	O
,	O
that	O
surface	O
can	O
be	O
functionalised	O
in	O
the	O
area	O
of	O
the	O
channel	O
.	O
</s>
