Biomedical Engineering Reference
In-Depth Information
silica..Although.the.silica.wing.is.harder.and.more.brittle.than.the.natural.butterly.wing,.
a.pair.of.tweezers.can.more.easily.handle.the.silica.wing..CVD.is.an.inexpensive.process.
used.to.faithfully.replicate.the.hierarchical.structure.of.the.natural.form.
9.3.2 Diamond-Like Carbon Wing by Focused ion Beam Chemical
Vapor Deposition with Computer-Aided Design
Watanbe. et. al.. (2005a,b). fabricated. the.
Morpho
-butterly-scale. quasi-structure. using. a.
focused.ion.beam.chemical.vapor.deposition.(FIB-CVD)..They.utilized.a.Ga
+
.ion.beam.to.
deposit.a.diamond-like.carbon.material.based.on.a.mixture.of.organics..Computer.aided.
design. was. used. to. control. the. FIB. with. a. 20.nm. ion. beam. to. produce. 80.nm. structures.
that.have.similar.morphology.to.the.
Morpho
.nanostructures.situated.within.the.wing..The.
process. took. about. 55.min. to. produce. a. 20.μm. long. sample.. This. process. is. not. ideal. for.
mass.production;.however,.the.fabrication.was.able.to.make.an.almost.exact.replica.of.the.
Morpho
.nanostructure.and.optical.characteristics.
9.3.3 Phosphor Wing by Solution Casting
Silver.et.al..(2005).reproduced.the.
Morpho
.nanostructure.by.casting.from.scales.of.a.but-
terly.using.a.precursor.phosphor.solution,.which.was.the.irst.nanostructure.made.from.
phosphor.. Briely,. a. section. of. the. butterly. wing. was. placed. between. two. quartz. plates.
containing. a. ilm. of. precursor. phosphor. solution. and. pressed.. After. removing. the. top.
quartz.plate,.the.butterly.wing.template.was.illed.in.with.precursor.phosphor.solutions,.
dried.at.80°C.for.1.h,.placed.in.a.furnace.at.100°C,.followed.by.a.gradual.increase.in.tem-
perature.to.700°C..After.30.min.of.calcination.at.700°C,.the.natural.template.was.burned.
off.and.removed,.leaving.a.cast.of.phosphor.wing.nanostructures..Although.the.fabricated.
phosphor. wing. structure. could. replicate. the. natural. butterly. wing. at. a. scale. down. to.
100.nm,.it.failed.to.demonstrate.any.photonic.properties.. It.was.speculated.that.the.pre-
cursor. phosphor. solution. did. not. penetrate. into. or. coat. the. lamellar. structures. located.
between. the. cross-ribbing. in. the. scales,. which. are. the. most. important. structures. in. the.
generation.of.diffraction.properties.
9.3.4 Al
2
O
3
Wing by Atomic Layer Deposition
Low.temperature.atomic.layer.deposition.(ALD).is.a.promising.low-cost.nanofabrication.
approach.to.alumina.replicas.of.the.butterly.wing.scales..Huang.et.al..(2006).replicated.the.
Morpho
.wing.structure.with.Al
2
O
3
.using.an.ALD.system.at.100°C..Pure.Al(CH
3
)
3
.(TMA).and.
deionized.H
2
O.were.used.as.precursors.for.Al
2
O
3
.deposition.onto.the.
Morpho
.nanostructure..
A.thin.ilm.was.formed.as.a.result.of.the.precursor.chemical.reaction..The.growth.rate.of.
Al
2
O
3
. could. be. controlled. at. 0.1.nm. per. cycle.. After. depositing. uniform. layers. of. Al
2
O
3
.
onto.the.natural.butterly.wing.scale.in.a.controlled.manner,.the.sample.was.annealed.at.
800°C.for.3.h.to.remove.the.original.template.and.crystallize.the.shell.structure..Due.to.the.
uniformity.of.the.Al
2
O
3
.ilm,.Al
2
O
3
.wings.replicated.by.low.temperature.ALD.deposition.
have.faithfully.replicated.the.shape,.orientation,.distribution,.and.photonic.properties.of.
the.“parent”.scales..In.particular,.the.photonic.properties.are.tunable.by.controlling.the.
thickness.of.the.Al
2
O
3
.layer.by.varying.the.number.of.ALD.deposition.cycles,.as.shown.in.
Figure.9.5.(Huang.et.al..2006,.Liu.et.al..2012a).
Due. to. the. self-limiting. and. surface. reaction. characteristics,. ALD. can. control. the.
ilm. growth. at. the. atomic. scale. and. realize. 3D. conformal. replication. with. high. idelity.
