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Thunder Lecture III. Shanghai Institute for Advanced Studies. Fudan University 04.04.2006. Nano-Bionik. Micro- and Nanotechnology in Nature. Ingo Rechenberg. Bionics Biomimicry Biomimetics. What is Bionik ?. The study of the results of biological evolution.

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Thunder Lecture III

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Thunder Lecture III


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Shanghai Institute for Advanced Studies

Fudan University 04.04.2006

Nano-Bionik

Micro- and Nanotechnology in Nature

Ingo Rechenberg


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Bionics Biomimicry Biomimetics

What is Bionik ?

The study of the results of biological evolution

from the engineering point of view

from the engineering point of view

Learning from nature‘s way of engineering


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Bacteria flagellum

Micro&nano-structured biological surfaces

Biological selfassembly

Protein machines

Biological receptors

Muscle filaments

Nano-Bionik


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The topics

The Lotus-Flower-Effect: Self-cleaning property through hydrophobic micro-dots.

The Moth-Eye-Effect: The art to be invisible through optical nano-burls.

The Gecko-Foot-Effect:Sticking on the wall through elastic nano-hairs.

The Sand-Skink-Effect:Reduction of friction and wear through nano-thresholds.

The Darkling-Beetle-Effect:Collecting dew through hydrophilic/hydrophobic micro-spots.

The Shark-Scale-Effect:Turbulence reduction through longitudinal micro-grooves.

The Water Strider-Effect: To keep dry through micro-hairs with nano-ridges.


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Nano-spikes

Nano-thresholds

Nano-grooves

Nano-humps

Nano-burls

Nano-bumps

Nano-ladders

Nano-ribs

Nano-knobs

Nano-patterns in nature

?

?


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The sacred Lotus flower is a symbol of purity in Asian religions.

The Lotus-Flower-Effect


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Honey rolls down from a “Lotus-Effect-spoon”

The Lotus-Effect®

Water droplets roll down the leaf of the Lotus flower

Glue rolls down the leaf of the Lotus flower

A droplet takes up the dirt while rolling down


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30μm

Microrelief of the leave

The development of the Lotus-Effect® paint

Bionik-product

Self cleaning


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Lotusan facade paint

Standard facade paint

Test areas at the wall of my house after 4 years


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Adhesion > Cohesion

Adhesion < Cohesion

Surface tension and wetting angle

Adhesion << Cohesion


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smooth surface

Lotus-Effect® surface

The Lotus-Effect in action


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Lotus-Effect® roof tile

Lotus-Effect® tie

Prof. Wilhelm Barthlott


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1×1 cm

engineering imitation

Secondary structure

Lotus leaf

The Lotus-Effect extended


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Water droplet

Water droplet

The Lotus-Effect extended


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The Moth-Eye-Effect


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130 x

420 x

1050 x

4120 x

Micro-burls

100nmØ

Micro-optics of the moth eye


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<

l

light

Air

Optical transparent layer

Reflection of the light is avoided by a continuously increasing refractive index of the optical medium

Glass

Deception of the light

The little burls on the surface of the optical medium work as a gentle increase of the refractive index


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All the light is captured by th eye

Moonlight is not mirrored (predatory!)

Night-flying insect


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Invisible Jelly Fish


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Technological imitation of the nanostructure of a moth eye. Periodicity of the burls: 300 nm.

Glass pane with

Moth-Eye-Effect


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The Moth-Eye-Effect


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The wonder of the Gecko toes


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500000000 nanohairs

2 kg (theoretically)

Photo: M. Moffet

Geckos get a grip using Van-der-Waals-forces

Gecko sticking at the wall


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The seta has 1000 nanohairs

The Gecko toe has 500000 microhairs (setae)

Nanostructure of the Gecko toe


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Adhesion effect through

Van-der-Waals-forces

The Gecko effect

Technical surface 1

Contact area

Technical surface

Technical surface 2

Nanohairs !

Large contact area

large adhesion force

Small contact area

small adhesion force

Microhair


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Synthetic Gecko hairs

necessary for spider man

(New Scientist 15. 05. 2003)


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Gecko-Tape


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?

The Sandfish lives in the Sahara desert

The Sandfish-Effect


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Sandfish ?

Fishing rod


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0 s

The Sandfish

¼ s

½ s

dives down


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Characteristics of the sandfish scales

M. Zwanzig, IZM

Friction

Abrasion

sand flow

Electron emission

8µm


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My Sahara Lab

Field

work

in the

Sahara

GPS:

N 31°-15‘–02“

W 03°-59‘–13“

Erg Chebbi


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Simple apparatus to measure the dynamic friction coefficient of flowing sand

Sand tubule

Angular scale

Object platform

Hand lever


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Measurement of the dynamic friction coefficient


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20°

Sand flow is moving

18°

Sand flow stops

Sandskink

Measurement of the angle of sliding friction


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0

40

0

35

0

30

sliding angle

0

25

n

0

20

o

n

d

l

f

o

n

ss

e

l

0

a

y

T

15

a

S

N

l

teel

k

G

n

0

10

i

S

k

S

Sahara-Measurement 2002

0

5

0

0

Sliding friction: Sandfish versus engineering materials


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Friction measurements with a sand-filled cylinder


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58 %

Sand-cylinder measurements 2003

Steel = 19°

Sliding angle:

Sandskink = 12° Caudal

Sandskink = 18° Cranial


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50nmØ

Sandfish scale under the electron mikroscop (REM)

scale

Sand sflow

8µm

at the back

at th belly


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Sand flow

6µm

Oblique view of the nano-thresholds


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Sliding direction

Size comparison

Grain of sand upon the thresholds


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Abrasion of the sandfish scales


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The sandskink always looks shiny

while

Man-made things soon get blunt in the desert wind !

The resistance to abrasion


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Simple apparatus for the abrasion tests

Sandfunnel

Sandblast

Objectplatform


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Impact point of the sandblast

Impact time: 10 hours !

Steel

Abrasive spot:

Glass


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Glass Magnification ≈200

Sand abrasion under the microscope

2 hours impact time

20 cm blast height

Scotch tape protected

Sand blast

Sandfish Magnification ≈1000

Sandfish Magnification ≈1000

Afterward

Before


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Kenyan Sandboa

Sandskink

Parallel Evolution


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Sandskink

Kenyan Sandboa

Sandskink

Parallel Evolution


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Aporosaura anchita

Sand-diving lizard in the Namib desert

Namib


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The Mongolian Death Worm

Allghoi khorkhoi

lives in the Ghobi dersert

?

Ghobi


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Electrical charging in a sand storm


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Night photo

Exposure time 20 s

Discharge spark on the back of the sandskink after a sand storm


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Triboelectric charging of a glass rod


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Triboelectric charging of a plastic rod


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Electron acceptor

Electron donator

Sandskink scale

Tail

Head

Directed tribo-electricity on the sandskink scales


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Observed by Ernő Németh

https://fridolin.tu-freiberg.de/archiv/pdf/VerfahrenstechnikNXmethErnX748129.pdf

Neutrally charged grain of plastic with oppositely charged spots


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Observed in Sahara

Sticking chain of sandgrains

Neutrally charged grain of sand can have oppositely charged spots


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Hypothesis:

The directed triboelectric experiment indicates the ease of an electron exchange from and to the Sandfish skin

Electric levitation hypothesis


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Sandgrain

The effect may work for some seconds, time enough for the sandfish to escape. After that the neutralised charge has to be refilled.

Sandfish

Electric levitation hypothesis


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Modern Sand Boarding


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The Darkling-Beetle-Effect


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Fog catching in

the Namib desert

made by nature

and

made by humans


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10mm

Andrew R. Parker and Chris R. Lawrence

Darklingbeetleofthe Namib desert

(Stenocara sp.)

Hydrophilic peaks

Hydrophobic burled lowland

similar to the Lotus-Effect®


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Hydrophobic burls

Fog droplets

Hydrophilic hills


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Hydrophobic burls

Fog droplets

Hydrophilic hills

Condensation


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Hydrophobic burls

Fog droplets

Hydrophilic hills

To the mouth of the beetle

Collected dew


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Waxen surface

Spray

Air flow

Glass spheres

Fan

Experiment of Parker and Lawrence


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Shark scale

The Shark-Scale-Effect


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0,5mm

The groove structure of the shark scales


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s

0

o

60

-2

s

-4

s

2

o

45

-6

s

-8

-10

0

6

2

4

D

W

Sawtooth-Grooves

W

0

Sawtooth-Grooves

%

Trapezoidal-grooves

Rectangular- grooves

Trapezoidal-grooves

s

2

Rectangular- grooves

*

s

BECHERTs experiments in the Berlin oil-channel


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Advertisement of a new swim suit


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Mounting a riblet foil on the wing of an airbus


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The Water-Strider-Effect


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Water strider skating on water


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Nano-grooves

Water

strider

Xuefeng Gao & Lei Jiang, Beijing

20μm

200nm


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Robostrider

Development of an artificial water strider

B.Chan, D.Hu


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The water spider never gets wet


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10mm

The hair of the water spider, a model for a new waterproof suit


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Thank for your attention

www.bionik.tu-berlin.de


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