Gecko Stations Lesson pptx

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15 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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“Sticking” with the Gecko


Van der Waals Forces and
Animal Adhesion

upload.wikimedia.org

http://www.gotpetsonline.com/pictures
-
gallery/reptile
-
pictures
-
breeders
-
babies/tokay
-
gecko
-
pictures
-
breeders
-
babies/pictures/tokay
-
gecko
-
0005.jpg

www.whyfiles.com

Activity Goal


Explain how geckos and jumping spiders
use van der Waals forces to adhere to
surfaces


Explain the relationship between mass of
an organism and number of setae/100
m
m
2


List some potential applications that use
gecko/jumping spider adhesion properties

Terms to Know


Micro




symbol:
m



definition: one millionth or 10
-
6



Micrometer or micron



symbol:
m
m



definition: one millionth of a meter



a human hair is about 50
m
m wide

http://images.google.com/imgres?imgurl=http://www.nsf.gov/od/lpa/news/03/images/wir
e_on_hair_big.jpg&imgrefurl=http://www.nsf.gov/od/lpa/news/03/pr03147_images.htm&
h=960&w=1228&sz=197&hl=en&start=3&sig2=rkwzYL2bDxq6t_bdIfOY
-
Q&um=1&tbnid=Y9V
-
_MzcLrD
-
RM:&tbnh=117&tbnw=150&ei=EvDfR
-
zxI4_eigGbwcTUBQ&prev=/images%3Fq%3Dhuman%2Bhair%2B%26um%3D1%26hl
%3Den%26rlz%3D1T4GGLJ_enUS248US253

Terms to Know


Nano



symbol: n



definition one billionth or 10
-
9



Nanometer



one billionth of a meter

http://microcosm.web.cern.ch

0.1 nm

1
-
10 nm

1
m
m

10
m
m

100
m
m

1 mm

1 cm

The Nanoworld


Nanotechnology


the control of shape and size at the nanoscale to
design and produce structures, devices, and
systems


Terms to Know

Terms to Know


INTERmolecular Forces


Weak forces of attraction between
molecules (i.e. dispersion, dipole
-
dipole, dipole
-
induced dipole, hydrogen
bonds)


Much weaker than intramolecular
forces



Van der Waals Forces


Forces that arise when a temporary
dipole in a non
-
polar molecule induces
a dipole in an adjacent non
-
polar
molecule

d
-

d+

d
-

d+

Terms to Know

Tokay Gecko (Gekko gecko)

an insect
-
eating, noisy reptile from South East Asia


Scansors


lamellae or gill
-
like structures on the bottom of the foot


Setae


hair
-
like bristles that come out of the scansors


Spatula


branches from the setae that end in flat triangles

http://en.wikipedia.org/wiki/Tokay_gecko

Gecko Morphology

http://images.google.com/imgres?imgurl=http://ist
-
socrates.berkeley.edu/~peattiea/gecko_foot_tour.jpg&imgrefurl=http://socrates.berkeley.edu/~peattiea/research_main.html&h=365
&w=
578&sz=77&hl=en&start=13&sig2=4K8MfL4Nukg2ujB
4fltpEw&um=1&tbnid=F98wzSz5PBo28M:&tbnh=85&tbnw=134&ei=CfXfR
-
bxLpiCiAGXrfzDBQ&prev=/images%3Fq%3Dgecko%2Bsetae%26um%3D1%26hl%3Den%26rlz%3D1T4GGLJ_enUS248US253

Terms to Know

Jumping Spider (
Evarcha arcuata)
-

a species of
jumping spider primarily found in Europe


Scopula


protrusion found at the tip of each foot


Setae


hair
-
like bristles that come out of the scopulae


Setules



densely cover the setae and broaden into flat, triangular
end

http://whyfiles.org/shorties/152sticky_spider/

Photo courtesy
Ed Nieuwenhuys


Getting a Grip on Spider Attachment: an AFM Approach to
Microstructure Adhesion in Arthropods

Antonia B Kesel, Andrew Martin, Tobias Seidl

a)
Tarsal claws, scopula and
hairs

b)
Scopulas differentiation into
setae

c)
Single setae covered with
setules

d)
Setule density is lower on
upperside of the setae

e)
Setules on the underside
broaden to a flat, triangluar
end

f)
The spider’s elements that
are in direct contact with the
substrate

Station 1

Graph Interpretation

Arzt, Eduard, Stanislav Gorb, and Ralph Spolenak

Proc Natl Acad Sci U S A. 2003 September 16; 100(19): 10603

10606.

Published online 2003 September 5. doi: 10.1073/pnas.1534701100.

Copyright

© 2003, The National Academy of Sciences

Q: What do each of the colored regions represent?

Q: What happens to the number of setae per 100
m
m
2

as the mass of the

organism increases?

Q: What kind of relationship is this?

flies

beetles

lizards

bugs

spiders

Station 1

Graph Interpretation

Arzt, Eduard, Stanislav Gorb, and Ralph Spolenak

Proc Natl Acad Sci U S A. 2003 September 16; 100(19): 10603

10606.

Published online 2003 September 5. doi: 10.1073/pnas.1534701100.

Copyright

© 2003, The National Academy of Sciences

The following pictures
are Scanning Electron
Microscope pictures of
an animal’s foot.
Match each picture
with the correct
organism: beetle, fly,
spider, lizard

flies

beetles

lizards

bugs

spiders

beetles

flies

spiders

lizards

Station 2

Experiment

How does the number of setae affect the strength of the
attachment force?



# of “setae”

4

8

16

32

Total

Force (N)

Mass chosen to weight

down toothbrush
_________________

Surface chosen


__________________


Station 3

Applications/
Biomimetics


2 Articles for students to read about newly designed gecko
-
tape.


http://www.scientificamerican.com/article
.cfm?id=gecko
-
inspired
-
adhesive
-
s

“Gecko
-
Inspired Adhesive Sticks It to
Traditional Tape”


http://www.sciencedaily.com/releases/20
12/02/120216165500.htm

“Gecko Feet
Inspire Amazing Glue That Can Hold
700 Pounds On Smooth Wall”


Station 3

Applications/
Biomimetics


2 Articles cont.



Answer questions relating to:


Advantages gecko tape might have over conventional tape


Problems in the manufacturing and use of gecko tape


Distance of setae to substrate


(nanometer scale)


Methods of adhesion in the gecko



(van
der

Waals forces)


Gecko and spider feet morphology

More Recent Developments

http://www.lclark.edu/~autumn/dept/Blog/4FB9A0EB
-
5911
-
4000
-
9D05
-
B1048F01E6C9.html

http://web.mit.edu/newsoffice/2008/adhesive
-
0218.html

Stanford University’s Sticky Bot

MIT’s dissolvable medical adhesive

Station 4

SEM Images

Students study SEM Images, read, and answer
questions about gecko and spider morphology

Jumping Spider












Why do geckos/spiders have so many setae?


they may not all have the correct orientation

How do they detach?

their setae need to be at an angle greater than 30
o

If all of a gecko’s setae were stuck to a surface at the same
time, how many pounds would it be able to support?
286 lbs!

Why do pictures “c” & “d” for the Jumping spider look different?


the bottom of the setae has a lot more
setules

than the top

Gecko

What is the advantage to having flat ends?


greater surface area

flies

beetles

lizards

bugs

spiders

Station 5


Spider Student?


y = m (x) + b

log (N
A
) = 0.699 log (m) + 13.8

How many setae/100
m
m
2

a 130 lb person
would need to stick to a wall?

The equation for the best
-
fit line on the graph can be written:









log of log of setae per 100
m
m
2



log of mass of organism in grams



How many setae/100
m
m
2

would a 130 lb person need to stick to a wall?


1
st
: Convert 130 lbs to grams.


mass = 59090 g












2
nd
: Substitute this value into the equation of the straight line.










N
A

= 1.37 X 10
17
setae/100
m
m
2











3
rd
: Convert this to setae / 100 cm
2





N
A

= 1.37 X 10
23

setae / 100 cm
2

+

+

13.8

log(m)

0.699

=

log(N
A
)

b

x

m

=

y

+

=

13.8

log(59090)

0.699

log(N
A
)




References:



Gecko
pic
-

http://images.iop.org/objects/phw/news/12/10/14/Gecko.jpg

Gecko
pic

2
-

http://www.exoticpetswholesale.com/i//sm_blue_gecko02.jpg

Tooth brush
pic

-

http://www.kosherimage.com/images/tbrush
-
4layflat.jpg

Spring scale
pic
-

http://www.enasco.com/prod/images/products/2A/VC131047l.jpg


This
powerpoint

comes from site below and was modified to meet needs of students.

teachers.oregon.k12.wi.us/
ehrlich
/NSTA08%20%20presentation.ppt