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Thunder Lecture III
Nano-Bionik
Micro- and Nanotechnology in Nature
Ingo Rechenberg
Shanghai Institute for Advanced Studies
Fudan University 04.04.2006
from the engineering point of view
What is Bionik ?
The study of the results of biological evolution
Learning from nature‘s way of engineering
from the engineering point of view
Bionics Biomimicry
Biomimetics
Nano-Bionik
Bacteria flagellum
Biological receptors
Biological self assembly
Muscle filaments
Protein machines
Micro & nano-structured biological surfaces
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.
The topics
Nano-patterns in nature
Nano-humps
Nano-grooves
Nano-bumpsNano-burls
Nano-spikes
Nano-ladders Nano-knobsNano-ribs
Nano-thresholds
? ?
The Lotus-Flower-Effect
The sacred Lotus flower is a symbol of purity in Asian religions.
The Lotus-Effect®
A droplet takes up the dirt while rolling down
Water droplets roll down the leaf of the Lotus flower
Glue rolls down the leaf of the Lotus flower
Honey rolls down from a “Lotus-Effect-spoon”
Self cleaning
30 μm
Bionik-product
The development of the Lotus-Effect
® paint
Microrelief of the leave
Lotusan facade paintStandard facade paint
Test areas at the wall of my house after 4 years
Surface tension and wetting angle
Adhesion > Cohesion
Adhesion < Cohesion
Adhesion << Cohesion
The Lotus-Effect in action
smooth surface
Lotus-Effect® surface
Prof. Wilhelm Barthlott
Lotus-Effect
® roof tile
Lotus-Effect
® tie
The Lotus-Effect extended
Lotus leaf
1 × 1 cm
engineering imitation
Secondary structure
The Lotus-Effect extended
Water droplet
Water droplet
The Moth-Eye-Effect
Micro-optics of the moth eye
130 x
Micro-burls100 nm Ø
420 x
1050 x
4120 x
light
The little burls on the surface of the optical medium work as a gentle increase of the refractive index
Reflection of the light is avoided by a continuously increasing refractive index of the optical medium
Deception of the light
Air
Glass
Optical transparent layer
Night-flying insect
All the light is captured by th eye
Moonlight is not mirrored (predatory!)
Invisible Jelly Fish
Glass pane withMoth-Eye-Effect
Technological imitation of the nanostructure of a moth eye. Periodicity of the burls: 300 nm.
The Moth-Eye-Effect
400 500 600 700 800Wavelength
nm
Re
flect
ivity
1
2
3
4
5
6
0
%
Without burl pattern
With burl pattern
The wonder of the Gecko toes
Gecko sticking at the wall
500 000 000 nanohairs2 kg (theoretically)
Ph
oto
: M
. Mo
ffetGeckos get a grip using Van-der-Waals-forces
The Gecko toe has 500 000 microhairs (setae)
The seta has 1 000 nanohairs
Nanostructure of the Gecko toe
Technical surface 1
Technical surface 2
Microhair
Nanohairs !
Technical surface
The Gecko effectAdhesion effect through
Van-der-Waals-forces
Small contact area
small adhesion force
Large contact area
large adhesion force
Contact area
Synthetic Gecko hairsnecessary for spider man
(New Scientist 15. 05. 2003)
Gecko-Tape
The Sandfish-Effect
?The Sandfish lives in the Sahara desert
Fishing rod
Sandfish ?
The Sandfish
dives down
0 s
¼ s
½ s
Friction
Abrasion
Electron emission
Characteristics of the sandfish scales
M. Zwanzig, IZM
8µm
sand flow
Fieldworkin theSahara
Erg Chebbi
My Sahara Lab
GPS:
N 31° - 15‘ – 02“
W 03° - 59‘ – 13“
Hand lever
Object platformAngular scale
Sand tubule
Simple apparatus to measure the dynamic friction coefficient of
flowing sand
Measurement of the dynamic friction coefficient
Sand flow is moving
Sand flow stops
20°
18°
Sandskink
Measurement of the angle of sliding friction
Sliding friction: Sandfish versus engineering materials
Sahara-Measurement 2002
0
50
100
150
200
Ski
n k
Sa
nd s
lidin
g a
ng
le
25 0
300
35 0
400
0
Ste
el
Gla
ss Teflo
n
Nyl
on
Friction measurements with a sand-filled cylinder
Skink
Steel
151618202021212121242425252626273030th August
25
20
15
10
5
0
0
0
0
0
0
0
ERG CHEBBI 4. - 31. 8. 2003An
gle
of s
lidin
g fri
ctio
n
Sliding angle:
Steel = 19°
Sandskink = 12° Caudal
Sandskink = 18° Cranial
Sand-cylinder measurements
2003
58 %
Sandfish scale under the electron mikroscop (REM)
8µm
Sand sflow
at the back at th belly
50 nm Ø
scale
Oblique view of the nano-thresholds
6 µm
Sand flow
Size comparison
Grain of sand upon the thresholds
Sli
din
g d
irec
tio
n
Abrasion of the sandfish scales
Man-made things soon get blunt in the desert wind !
The sandskink always looks shiny
while
The resistance to abrasion
Simple apparatus for the abrasion tests
30 cm
Sandfunnel
Sandblast
Objectplatform
Impact point of the sandblast
Impact time: 10 hours !
Abrasive spot:Steel
Glass
Sand abrasion under the microscope
Before Afterward
2 hours impact time
20 cm blast height
Glass Magnification ≈ 200
Sandfish Magnification ≈ 1000 Sandfish Magnification ≈ 1000
Scotch tape protected Sand blast
Sandskink
Parallel Evolution
Kenyan Sandboa
Sandskink
Parallel Evolution
Sandskink Kenyan Sandboa
Sand-diving lizard in the Namib desert
Namib
Aporosaura anchita
Allghoi khorkhoi
The Mongolian Death Worm
lives in the Ghobi dersert
?
Ghobi
Electrical charging in a sand storm
Discharge spark on the back of the sandskink after a sand storm
Night photoExposure time 20 s
Triboelectric charging of a glass rod
Triboelectric charging of a plastic rod
Directed tribo-electricity on the sandskink scales
Electron donatorElectron acceptor
Sandskink scale
Head Tail
Neutrally charged grain of plastic with oppositely charged spots
Observed by Ernő Németh
https://fridolin.tu-freiberg.de/archiv/pdf/VerfahrenstechnikNXmethErnX748129.pdf
Neutrally charged grain of sand can have oppositely charged spots
Observed in Sahara
Stic
king
cha
in o
f sa
ndgr
ains
Hypothesis:
The directed triboelectric experiment indicates the ease of an electron exchange from and to the Sandfish skin
Electric levitation hypothesis
Sandgrain
Electric levitation hypothesis
Sandfish
The effect may work for some seconds, time enough for the sandfish to escape. After that the neutralised charge has to be refilled.
Modern Sand Boarding
The Darkling-Beetle-Effect
Fog catching in
the Namib desert
made by humans
made by nature
and
Darkling beetle of the Namib desert (Stenocara sp.)
Andrew R. Parker and Chris R. Lawrence
10 mHydrophobic burled lowland
Hydrophilic peaks
similar to the Lotus-Effect ®
Fog droplets
Hydrophilic hills
Hydrophobic burls
Fog droplets
Hydrophilic hills
Hydrophobic burls
Condensation
Fog droplets
Hydrophilic hills
Hydrophobic burls
Collected dew
To the mouth of the beetle
Air flo
w
Experiment of Parker and Lawrence
Spray
Fan
Waxen surface
Glass spheres
The Shark-Scale-Effect
Shark scale
The groove structure of the shark scales
0,5 mm
BECHERTs experiments in the Berlin oil-channel
0 2 4 6
0
-2
-4
-6
-8
-10
60o
45o
s
s
s 2
s
WW0
%
s
s 2
*
Sawtooth-Grooves
Trapezoidal-grooves
Rectangular- grooves
Sawtooth-Grooves
Trapezoidal-grooves
Rectangular- grooves
Advertisement of a new swim suit
Mounting a riblet foil on the wing of an airbus
The Water-Strider-Effect
Water strider skating on water
Water strider
Nano-grooves
200 nm20 μmXuefeng Gao & Lei Jiang, Beijing
Robostrider
B. Chan, D. Hu
Development of an artificial water strider
The water spider never gets wet
10 m
The hair of the water spider, a model for a new waterproof suit
Thank for your attention
www.bionik.tu-berlin.de