Thunder Lecture III Fudan University 04 2006

Thunder Lecture III

Fudan University 04. 2006 Nano-Bionik Micro- and Nanotechnology in Nature Ingo Rechenberg Shanghai Institute for Advanced Studies

s etic m omi What is Bionik ? s ic Bion i y B r imic Biom The study of the results of biological evolution from the engineering point of view Learning from nature‘s way of engineering

Bacteria flagellum Micro & nanostructured biological surfaces Nano-Bionik Biological self assembly Protein machines Biological receptors Muscle filaments

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 nanothresholds. The Darkling-Beetle-Effect: Collecting dew through hydrophilic/hydrophobic micro-spots. The Shark-Scale-Effect: Turbulence reduction through longitudinal micro -grooves.

Nano-grooves Nano-spikes Nano-thresholds Nano-patterns in nature Nano-burls Nano-humps Nano-bumps ? Nano-ribs ? Nano-ladders Nano-knobs

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

The Lotus-Effect® Water droplets roll down the leaf of the Lotus flower Honey rolls down from a “Lotus-Effect -spoon” Glue rolls down the leaf of the Lotus flower A droplet takes up the dirt while rolling down

30 μm Microreli ef of the leave The development of the Lotus-Effect ® paint Self cleaning Bionik-product

Standard facade paint Lotusan facade paint Test areas at the wall of my house after 4 years

Adhesion > Cohesion Adhesion < Cohesion Surface tension and wetting angle Adhesion << Cohesion

th moo s s ce fa ® sur ct Effe s- ce urfa Lotu The Lotus-Effect in action

Lotus-Effect ® roof tile Lotus-Effect ® tie Prof. Wilhelm Barthlott

Secondary structure 1 × 1 cm Lotus leaf engineering imitation The Lotus-Effect extended

Water droplet The Lotus-Effect extended

The Moth-Eye-Effect

130 x 420 x Micro-optics of the moth eye 1050 x 4120 x Micro-burls 100 nm Ø

Air Optical transparent layer Glass Reflection of the light is avoided by a continuously increasing refractive index of the optical medium Deception of the light < l light The little burls on the surface of the optical medium work as a gentle increase of the refractive index

All the light is captured by th eye Moonlight is not mirrored (predatory!) Night-flying insect

Invisible Jelly Fish

Technological imitation of the nanostructure of a moth eye. Periodicity of the burls: 300 nm. Glass pane with Moth-Eye. Effect

The Moth-Eye-Effect

The wonder of the Gecko toes

Photo: M. Moffet 5002 kg (theoretically) 000 nanohairs Geckos get a grip using Van-der-Waals-forces Gecko sticking at the wall

The seta has 1 000 nanohairs The Gecko toe has 500 000 microhairs (setae) Nanostructure of the Gecko toe

Technical surface 1 Adhesion effect through The Gecko effect Van-der-Waals-forces Contact area Technical surface 2 Technical surface Nanohairs ! Large Small contact area large adhesion small adhesion force Microhair

Synthetic Gecko hairs necessary for spider man (New Scientist 15. 05. 2003)

Gecko-Tape

? The Sandfish lives in the Sahara desert The Sandfish-Effect

Sandfish ? Fishing rod

0 s The Sandfish ¼ s ½ s dives down

Characteristics of the sandfish scales M. Zwanzig, IZM Friction Abrasion Electron emission w flo d san 8µm

My Sahara Lab GPS: Field work in the Sahara N 31° - 15‘ – 02“ Erg W 03° - 59‘ – 13“ Chebbi

Simple apparatus to measure the dynamic friction coefficient of flowing sand Sand tubule Angular scale Object platform Hand lever

Measurement of the dynamic friction coefficient

20° Sand flow is moving 18° Sand flow stops Sandskink Measurement of the angle of sliding friction

0 0 35 0 30 0 15 0 10 0 5 Steel 0 Glass 20 Nylon 0 Teflon 25 Skink Sand sliding angle 40 Sahara-Measurement 2002 0 0 Sliding friction: Sandfish versus engineering materials

Friction measurements with a sand-filled cylinder

58 % Sandcylinder measuremen ts 2003 Steel = 19° Sliding angle: Sandskink = 12° Caudal Sandskink = 18° Cranial

Sandfish scale under the electron mikroscop (REM) 50 nm Ø scale ow sfl nd Sa 8µm at the back at th belly

Sand flow 6 µm Oblique view of the nano-thresholds

Sliding direction Size comparison Grain of sand upon the thresholds

Abrasion of the sandfish scales

The sandskink always looks shiny while Man-made things soon get blunt in the desert wind ! The resistance to abrasion

Simple apparatus for the abrasion tests Sandfunnel Sandblast Objectplatform

Impact point of the sandblast Impact time: 10 hours ! Steel Abrasive spot: Glass

Sand abrasion under the microscope Glass Magnification ≈ 200 2 hours impact time 20 cm blast height Scotch tape protected Sandfish Magnification ≈ 1000 Befor e Sand blast Afterwar d

Kenyan Sandboa Sandskink Parallel Evolution

Sandskink Kenyan Sandboa Parallel Evolution

Aporosaura anchita Sand-diving lizard in the Namib desert Namib

The Mongolian Death Worm Allghoi khorkhoi Ghobi lives in the Ghobi dersert ?

Electrical charging in a sand storm

Night photo Exposure time 20 s Discharge spark on the back of the sandskink after a sand storm

Triboelectric charging of a glass rod

Triboelectric charging of a plastic rod

Electron acceptor Electron donator Sandskink scale Head Tail Directed tribo-electricity on the sandskink scales

Observed by Ernő Németh https: //fridolin. tufreiberg. de/archiv/pd f/Verfahrenstechnik NXmeth. Ern. X 748129. pdf Neutrally charged grain of plastic with oppositely charged spots

Neutrally charged grain of sand can have oppositely charged spots Sticking chain of sandgrains Observed in Sahara

Hypothesis: The directed triboelectric experiment indicates the ease of an electron exchange from and to the Sandfish skin Electric levitation hypothesis

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

Modern Sand Boarding

The Darkling-Beetle-Effect

Fog catching in the Namib desert made by nature and made by humans

Darkling beetle of the Namib desert (Stenocara sp. ) Hydrophilic peaks Hydrophobic burled similar to the Lotus-Effect ® lowland 10 mm Andrew R. Parker and Chris R. Lawrence

Hydrophobic burls Fog droplets Hydrophilic hills

Hydrophobic burls Fog droplets Hydrophilic hills Condensation

Hydrophobic burls Fog droplets Hydrophilic hills To the mouth of the beetle Collected dew

Waxen surface Ai rf lo w Spray Glass spheres Fan Experiment of Parker and Lawrence

Shark scale The Shark-Scale-Effect

0, 5 mm The groove structure of the shark scales

s DW W 0 % 0 o 60 Sawtooth-Grooves -2 Sawtooth-Grooves s Trapezoidal-grooves -4 s 2 o 45 -6 Rectangular- grooves Trapezoidal-grooves s -8 s 2 -10 Rectangular- grooves 0 2 4 s * 6 BECHERTs experiments in the Berlin oil-channel

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

Nano-grooves Water stride r Xuefeng Gao & Lei Jiang, Beijing 20 μm 200 nm

Robostrider Development of an artificial water strider B. Chan, D. Hu

The water spider never gets wet

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

Thank for your attention www. bionik. tu-berlin. de