Biomedical Engineering Reference
In-Depth Information
9.4 Applications
Butterly-inspired. nanotechnologies. have. many. useful. applications. that. draw. on. the.
unique.structure.of.butterly.wings..These.applications.are.mainly.based.on.the.unique.
optical.properties.(iridescence).of.these.wings,.and.to.a.lesser.degree.utilize.their.hydro-
phobicity.and.porous.structure..Due.to.the.ability.of.butterly.wings.to.change.colors.based.
on.the.surrounding.materials,.there.are.many.possible.applications.in.the.ield.of.chemi-
cal.and.biological.sensors..In.particular,.butterly.wing.structures.can.rapidly.respond.to.
temperature. changes. with. very. high. sensitivity.. Therefore,. biomimetic. wing. structures.
can.serve.as.thermal.imaging.sensors..Butterly-inspired.nanostructures.could.be.invalu-
able.to.display.technology.that.makes.use.of.structural.colors.that.do.not.fade.with.time.or.
exposure.to.light..As.the.hierarchical.architecture.of.butterly.wings.has.a.light-harvesting.
function,.biomimetic.wing.structures.can.serve.as.solar.collectors.in.solar.panels.and/or.
photo.catalysts.to.eficiently.convert.light.energy.to.electrical.energy..These.applications.
are.detailed.in.the.following.sections.
9.4.1  Photonic Sensors
9.4.1.1  Chemical Sensors
Potyrailo. and. his. team. have. discovered. that. the. iridescent. scales. of. a. Morpho . butterly.
wing. change. color. in. response. to.individual. vapors,.which. can. be. used. as. an.acute. gas.
sensor.(Potyrailo.et.al..2007)..In.the.presence.of.different.vapors,.the.wing's.scales.could.
give.rise.to.different.optical.responses..By.measuring.the.spectrum.of.light.relected.off.
of.the.wing's.scales,.individual.vapors.in.the.gas.environment.near.the.nanostructure.of.
the.wing.could.be.analyzed.for.chemical.identity.as.well.as.concentration..By.varying.the.
separation.of.the.scales,.different.vapors.could.be.detected.and.identiied.due.to.the.vary-
ing.wavelengths.of.light.relected,.including.closely.related.water,.methanol,.ethanol,.and.
isomers. of. dichloroethylene. vapors.. It. demonstrates. that. mimicking. the. butterly. wing.
structure.could.provide.highly.selective.and.eficient.chemical.sensors.
Song.et.al..(2009).have.successfully.fabricated.an.SnO 2 .replica.of.butterly.wings.and.dem-
onstrated. the. sensor. capacity. of. detecting. ethanol. vapor. at. 170°C.. The. SnO 2 . wing. sensor.
exhibited.hierarchical.structures,.including.well-organized.macroporous.frameworks,.con-
nective.hollow.tubes.and.active.nanocrystallites.in.thin.mesoporous.walls,.allowing.quick.
diffusion. of. gas. molecules.. These. qualities. lead. to. a. very. good. ethanol. sensor. with. high.
sensitivity.(49.8-50.ppm.ethanol),.rapid.response.time.(11.s),.and.short.recovery.time.(31.s)..
In.order.to.better.understand.and.design.biomimetic.wing.sensors,.Yang.et.al..further.mod-
eled.the.optical.relection.changes.in.response.to.environmental.media.based.on.multilayer.
rigorous.coupled.wave.analysis.(MRCWA).(Yang.et.al..2011)..The.theoretical.prediction.was.
consistent.with.experimental.results.for.sensing.air,.ethanol,.and.methanol..It.was.predicted.
that.the.sensitivity.and.selectivity.could.be.increased.by.modulating.the.asymmetry.and.
ordered.dimensional.variation.of.the.lamellar.structure,.which.could.provide.a.guideline.
for.engineering.design.of.next.generation.of.biomimetic.chemical.sensors.
9.4.1.2  Biosensors
Takeoka. and. Seki. (2007). synthesized. a. biform.structural.colored. thermosensitive. gel. by.
implanting.N-isopropylacrylamide.(NIPA).gel,.a.well-known.thermosensitive.gel.formed.
by.free-radical.polymerization,.with. Morpho .scales..The. Morpho .wings.were.then.placed.
 
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