<s>
4-dimensional	B-Device
printing	I-Device
(	O
4D	B-Device
printing	I-Device
;	O
also	O
known	O
as	O
4D	O
bioprinting	O
,	O
active	O
origami	O
,	O
or	O
shape-morphing	O
systems	O
)	O
uses	O
the	O
same	O
techniques	O
of	O
3D	O
printing	O
through	O
computer-programmed	O
deposition	O
of	O
material	O
in	O
successive	O
layers	O
to	O
create	O
a	O
three-dimensional	O
object	O
.	O
</s>
<s>
However	O
,	O
in	O
4D	B-Device
printing	I-Device
,	O
the	O
resulting	O
3D	O
shape	O
is	O
able	O
to	O
morph	O
into	O
different	O
forms	O
in	O
response	O
to	O
environmental	O
stimulus	O
,	O
with	O
the	O
4th	O
dimension	O
being	O
the	O
time-dependent	O
shape	O
change	O
after	O
the	O
printing	O
.	O
</s>
<s>
As	O
opposed	O
to	O
fused-deposition	O
modeling	O
,	O
where	O
the	O
extruded	O
material	O
hardens	O
immediately	O
to	O
form	O
layers	O
,	O
4D	B-Device
printing	I-Device
is	O
fundamentally	O
based	O
in	O
stereolithography	O
,	O
where	O
in	O
most	O
cases	O
ultraviolet	O
light	O
is	O
used	O
to	O
cure	O
the	O
layered	O
materials	O
after	O
the	O
printing	O
process	O
has	O
completed	O
.	O
</s>
<s>
Most	O
4D	B-Device
printing	I-Device
systems	O
utilize	O
a	O
network	O
of	O
fibers	O
that	O
vary	O
in	O
size	O
and	O
material	O
properties	O
.	O
</s>
<s>
Stress	O
relaxation	O
in	O
4D	B-Device
printing	I-Device
is	O
a	O
process	O
in	O
which	O
a	O
material	O
assembly	O
is	O
created	O
under	O
stress	O
that	O
becomes	O
"	O
stored	O
"	O
within	O
the	O
material	O
.	O
</s>
<s>
Dr.	O
Lijie	O
Grace	O
Zhang	O
's	O
research	O
team	O
at	O
the	O
George	O
Washington	O
University	O
created	O
a	O
new	O
type	O
of	O
4D-printable	O
,	O
photo-curable	O
liquid	O
resin	B-Language
.	O
</s>
<s>
This	O
resin	B-Language
is	O
made	O
of	O
a	O
renewable	O
soybean-oil	O
epoxidized	O
acrylate	O
compound	O
that	O
is	O
also	O
biocompatible	O
.	O
</s>
<s>
This	O
resin	B-Language
adds	O
to	O
the	O
small	O
group	O
of	O
3D-printable	O
resins	B-Language
and	O
is	O
one	O
of	O
the	O
few	O
that	O
are	O
biocompatible	O
.	O
</s>
<s>
A	O
laser	O
3D-printed	O
sample	O
of	O
this	O
resin	B-Language
was	O
subjected	O
to	O
temperature	O
fluctuations	O
from	O
-18	O
°C	O
to	O
37°C	O
and	O
exhibited	O
full	O
recovery	O
of	O
its	O
original	O
shape	O
.	O
</s>
<s>
This	O
research	O
article	O
is	O
one	O
of	O
the	O
first	O
that	O
explore	O
the	O
use	O
of	O
plant	O
oil	O
polymers	O
as	O
liquid	O
resins	B-Language
for	O
stereolithography	O
production	O
in	O
biomedical	O
applications	O
.	O
</s>
<s>
There	O
are	O
some	O
existing	O
techniques/technologies	O
that	O
could	O
potentially	O
be	O
applied	O
and	O
adjusted	O
for	O
4D	B-Device
printing	I-Device
.	O
</s>
<s>
Polyaniline	B-Algorithm
and	O
polypyrrole	B-Algorithm
(	O
PPy	B-Algorithm
)	O
are	O
,	O
in	O
particular	O
,	O
good	O
conducting	O
materials	O
and	O
can	O
be	O
doped	O
with	O
tetrafluoroborate	O
to	O
contract	O
and	O
expand	O
under	O
an	O
electric	O
stimulus	O
.	O
</s>
