Biomedical Engineering Reference
In-Depth Information
and.in.situ.polymerization..An.SiO
2
.replica.was.irst.fabricated.through.the.ultrasonica-
tion.technique.as.described.above..Next,.the.SiO
2
.replica.was.placed.on.a.microslide.and.
dipped.into.a.1-2.mL.pyrrole.solution.followed.by.0.1.mL.FeCl
3
.solution,.in.which.pyrrole.
monomers.reached.the.empty.space.between.the.silica.particles..Finally,.polymerization.
was. carried. out. at. 65°C. for. 3.h,. followed. by. soaking. in. HF. solution. for. 24.h. to. remove.
the.SiO
2
.template..The.resulting.polypyrrole.replica.exhibited.brilliant.colors.and.showed.
potential.as.a.biosensor..It.provides.a.new.avenue.for.fabricating.photonic.structures.using.
conductive.polymers.
9.3.10 PDMS replica of Wing Nanostructures by Molding Lithography
In.order.to.realize.mass.production,.Kang.et.al..applied.soft.lithography.to.the.fabrication.
of. the. polydimethylsiloxane. (PDMS). mold. of. the. multilayer. scales. of. a.
Morpho
. butterly.
(Kang. et. al.. 2010).. The. PDMS. was. irst. placed. on. top. of. a. wing. and. then. covered. by. a.
polyethylene. plate. and. a. glass. substrate. while. applying. signiicant. pressure. at. 65°C..
A. PDMS. replica. of. the. nanostructure. of. the. wing. scales. was. formed.. After. removing.
the. glass. substrate. and. the. polyethylene. plate,. the. molding. was. sputtered. with. Pt/Au.
to. mimic. the. coloring. of.
Morpho
. butterly. wings.. In. this. way,. tree-like. structures. were.
formed,. replicating. the.
Morpho
. nanostructures.. These. nanostructures. manifest. optical.
and. hydrophobic. properties,. which. are. similar. to. those. found. in. the. natural.
Morpho
.
nanostructures..This.molding.lithography.offers.an.effective.approach.to.mass.production.
of.biomimetic.photonic.structures.
9.3.11 Direct-Write of Biomimetic Butterfly Wings
The.use.of.direct-write.process.will.allow.us.to.create.the.hierarchical.structure.without.
the. need. for. a. natural. butterly. wing. as. a. template.. Saito. has. utilized. electron. beam.
lithography.(also.called.e-beam.lithography.or.EBL).to.fabricate.
Morpho
.wing.structures.
(Saito. et. al.. 2009,. Saito. 2011).. First,. a. quasi-1D. nanopattern. on. a. quartz. substrate. was.
fabricated. by. conventional. EBL,. which. contains. both. the. in-plane. randomness. and.
line. shapes. to. simultaneously. mimic. the. randomness. and. quasi-1D. anisotropy.. Then,. a.
multilayer.composed.of.alternating.layers.of.high.(TiO
2
,.40.nm.thickness).and.low.(SiO
2
,.
75.nm.thickness).refractive.index.materials.were.deposited.on.the.nanopatterned.substrate.
by.step-by-step.e-beam-assisted.deposition.to.replicate.the.lamellar.structures.and.their.
optical. features. as. shown. in. Figure. 9.4.. EBL. provides. a. simple. and. controllable. process.
to. reproduce. butterly. wing. structure. without. the. need. for. a. template.. Although. EBL.
needs.expensive.tools.and.is.time.consuming,.it.is.advantageous.because.it.can.be.used.
to.generate.deliberate.artiicial.wing.structures.as.a.mask.or.a.mold.and.can.be.combined.
with.nanoimprinting.or.mold.lithography.for.mass.production.
Laser.direct-write.in.combination.with.particle-assisted.laser.nanofabrication,.which.
can.selectively.and.locally.pattern,.has.demonstrated.the.potential.to.fabricate.photonic.
crystal.structures.mimicking.the.natural.butterly.wing.scale.(Pena.et.al..2010)..To.start.
this. process,. the. Si. substrate. was. cleaned. and. deposited. with. a. uniform. monolayer. of.
SiO
2
. microspheres.. These. SiO
2
. microspheres. self-assembled. into. a. hexagonal. array. of.
silica..Next.a.Gaussian.laser.beam.was.used.to.ablate.the.SiO
2
.microspheres.at.desired.
sites..This.laser.direct-write.enables.the.processing.of.microsized.patterns.composed.of.
submicron.and/or.nanostructures.on.various.substrates..Refer.to.Chapters.12.and.13.for.
more.information.
