72.the Natural Patterns of Self-cleaning Surfaces Micro-Nanotopography Analysis of Superhydrophobic...

8/13/2019 72.the Natural Patterns of Self-cleaning Surfaces Micro-Nanotopography Analysis of Superhydrophobic Leaves.favret ..................................

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2nd World Scientific Congress Challenges in Botanical Research

and Climate Chan e

The natural atterns of self-cleanin surfaces:

Delft, The Netherlands, 29 June - 4 July 2008

Micro-nanotopography analysisof superhydrophobic leaves

Eduardo A. Favret and Ana M. Molina

Jardn Botnico A. Ragonese

INTA - Argentina


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Bionics Biomimetism

The study of theformation, structure, or

produced substancesand materials and

biological mechanisms

Interdisciplinary Science

an processes espec a y

for the purpose ofsynthesizing similarroducts b artificial

Biological surfacesmechanisms which

mimic natural ones."

Functional properties Lotus(Self-Cleaning surface)

Moth Eye(Antirreflective surface)

Gecko(Antifriction surface) (Dry-adhesive surface)


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Lotus EffectSelf-Cleaning Surfaces

Superhydrophobicity

ys ca opograp y Chemical (composition)

Multiscale roughness

(long chains C, H and O)

low surface energy materials/coatings or by introducing roughness.


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Multiscale roughness

Applications of self-cleaning surfacesWindshields exterior aints for buildin s navi ation-shi s and

utensils, roof tiles, textiles and reduction of drag in fluid flow


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Superhydrophobic (SH) condition

con ac ang e < 10 (sliding angle) a r < 10 (Hysteresis)

The Fakir Effect

Drop bouncing on a SH surface

Courtesy ofDr. D. Qur (France)

Courtesy of Dr. D. Qur (France)


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Research lines in SH surfaces

Chemical compositionlow free ener surface

Fabrication ofmicro/nano-

Binary structure: Micro-nano topographyHierarchical structures (70-500nm, 3-100m)

.

D. Qur B. BhushanM. Nosonovsky

C. Neinhuis

K. KochN. Patankar

S. Herminghaus T. McCarthy


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Journals and Paperson SH surfaces

BARTHLOTT, W. and C. NEINHUIS. 1997. Purity of the sacred lotus, or escape fromcontamination in io ogica sur aces. P l a n t a . 202: 1-8.

OTTEN, A. and S. HERMINGHAUS. 2004. How Plants Keep Dry: A Physicists Point of View.

La n g m u i r . 20: 2405-2408.

QUR, D. and M. REYSSAT. 2008. Non-adhesive lotus and other hydrophobic materials.Ph i l . T r a n s . R . Soc . A . 366: 15391556.

NOSONOVSKY, M. and B. BHUSHAN. 2008. Roughness-induced superhydrophobicity: a

way to design non-adhesive surfaces. Jo r n a l o f P h y s ic s : Co n d e n s . M a t t e r . 20 (2008)225009 (30pp).

PATANKAR, N. A. 2004. Mimicking the Lotus Effect: Influence of Double Roughness- . . .

GUO, Z. and W. LIU. 2007. Biomimic from the superhydrophobic plant leaves in nature:Binary structure and unitary structure. P la n t S ci e n c e . 172: 1103-1112.


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Our Research Objective

Describe and find the topographical patternso e super y rop o c sur aces

Is there any difference between the binary and unitary structures?

Approach

Topograp ica c aracterization o ea samp esSEM-ESEM Images

Quantitative Measurementsana ys sana ys s


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Leaf Samples

Brassica Xanthosoma and Colocasia

TropaeolumOryza


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Wetting conditions

Tropaeolum

Colocasia

Brassica


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Micro-nanostructure of leaf surfaces

- -Microstructure: micro-bumps (diameter 2-20m, distance 20-40m,height 10-30m)

,

Colocasia

Nelumbo

Courtesy of Dr. C. Neinhuis (Germany)

Xanthosoma Brassica


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The peaks of the RIMAPS spectrumindicate main angular directions of the

topographic pattern

This technique consists basically of rotating the image using availableal orithms of commercial software and calculatin the x-ste of the two-dimensional Fourier transform for each y-line of the new image obtained

after rotation. As a consequence, averaged power spectra are obtained foreach angular position. The corresponding maximum values are plotted asa function of rotation an le obtainin the RIMAPS s ectrum.

1.0

0.6

0.8

APS(u.a.)

0 50 100 150 200 250 300 3500.2

0.4

gra os

FUENTES, N. and FAVRET, E. (2002): A new surface characterization technique: RIMAPS

(Rotated Image with Maximun Average Power Spectrum), Jo u r n a l o f M i cr o s c o p y . 206, 72-83.


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RIMAPS Results

Co l o c a s i a

(adaxial side)X an t h o so m a

(abaxial side)

Co l o c a s i a

Epicuticular wax

0.8

1.0Xan2 400xCol7.10 400x

.)

0.8

1.0Col7.10 400xT21a col 6400x

.)

0.2

0.4

0.6

MAPS(a

.

0.2

0.4

0.6

MAPS(a

.

0 30 60 90 120 150 180

0.0

RI (degrees)

0 30 60 90 120 150 180

0.0

RI (degrees)


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RIMAPS Results (cont.)

X a n t h o s o m a (abaxial side)

Xanthosoma500x

Ideal micro-pattern

0.8

1.0

.)

0.2

0.4

0.6

MAPS(a

.

0 20 40 60 80 100 120 140 160 180

0.0

.

RI (degrees)


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O r y z a (adaxial side)

1.0

Oryza500x

0.6

0.8

.u.)

Oryza2000x

0.2

0.4

MAPS

(

0 20 40 60 80 100 120 140 160 1800.0

RI (degrees)


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T r o p a e o l u m (adaxial side)

0.8

1.0

u.)

ropaeo um x

Tropaeolum800x

Tropaeolum1600

0.2

0.4

.

MAPS(a.

0 20 40 60 80 100 120 140 160 180

0.0

RI (degrees)


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B r a s s i c a (adaxial side)

0.8

1.0

u.)

Brassica1500x

0.2

0.4

.

MAPS(a.

0 20 40 60 80 100 120 140 160 1800.0

RI (degrees)


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RIMAPS Polar Graphs

Xanthosoma


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RIMAPS Polar Graphs

B r a s s i c a

T r o p a e o l u m


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Conclusions

RIMAPS results:The topographical pattern shows difference depending on the size ofthe studied area for the same s ecies.The Colocasia micro-pattern has a great similarity with its nano-patternThere are different micro-patternsColocasia andXanthosoma (abaxial side) has similar patterns for low

Brassica has a nano-pattern almost similar to the micro-structure ofXanthosoma (abaxial side)

u ure ana yses:Nano-pattern (epicuticular wax)Leaf with unitary structure (e.g. Ramee -Boehmeria iongispica steud-)Alchemilla vul aris h dro hilic hairs on a h dro hobic substrateHydrophilic leaf surfaces (e.g. Magnolia grandiflora)

Herbarium samples


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BotanicalBotanical GardenGarden AA.. RagoneseRagonese

A future centre in research and education on Biomimetism

a ure o ers us e c en an e ec ve mo e s or edevelopment of mechanicals tools, computational algorithms andnew materials

We can learn from Nature new production processes, withouttoxic waste and pollution

disappearing


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Thank you!

72.the Natural Patterns of Self-cleaning Surfaces Micro-Nanotopography Analysis of Superhydrophobic...

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