1. “Sticking” with the Gecko

2. 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

3. 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 2 List some potential applications that use gecko/jumping spider adhesion properties

4. Terms to Know Micro symbol:  definition: one millionth or 10 -6 Micrometer or micron symbol:  m definition: one millionth of a meter a human hair is about 50  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

5. Terms to Know Nano symbol: n definition one billionth or 10 -9 Nanometer one billionth of a meter

6. http://microcosm.web.cern.ch 0.1 nm1-10 nm 1  m 10  m 100  m 1 mm1 cm The Nanoworld

7. Nanotechnology the control of shape and size at the nanoscale to design and produce structures, devices, and systems Terms to Know

8. 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 --  --

9. 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

10. 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

11. 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 Ed Nieuwenhuys

12. 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

13. 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. CopyrightCopyright © 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 2 as the mass of the organism increases? Q: What kind of relationship is this? flies beetles lizards bugs spiders

14. 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. CopyrightCopyright © 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

15. Station 2—Experiment How does the number of setae affect the strength of the attachment force? # of “setae”481632 Total Force (N) Mass chosen to weight down toothbrush _________________ Surface chosen __________________

16. Station 2—Experiment Student Procedure: Students will use modified tooth brushes, similar but longer than the picture on previous slide. These modified toothbrushes will have different numbers of “setae” on them Students will choose a mass to tape to the toothbrush, weighing it down to the surface Students will use the spring scale to measure the force (N) needed to move the toothbrush along a surface Students will record the data in a table, then analyze it to write a summary.

17. Station 2—Experiment Supplies: Modified toothbrushes with different number of “setae” on them and loop at the bottom to attach the spring scale Spring scale Tape Many different mass weights Different types of surfaces (tile, glass, plastic, wood, etc.

18. 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.scientificamerican.com/article.cfm?id=gecko-inspired-adhesive-s http://www.sciencedaily.com/releases/20 12/02/120216165500.htm “Gecko Feet Inspire Amazing Glue That Can Hold 700 Pounds On Smooth Wall”http://www.sciencedaily.com/releases/20 12/02/120216165500.htm

19. 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

20. 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

21. 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

22. 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 2 a 130 lb person would need to stick to a wall?

23. The equation for the best-fit line on the graph can be written: log of log of setae per 100  m 2 log of mass of organism in grams How many setae/100  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 2 3 rd : Convert this to setae / 100 cm 2 N A = 1.37 X 10 23 setae / 100 cm 2 + + 13.8log(m)0.699 = log(N A ) bxm=y +=13.8log(59090)0.699log(N A )

24. References: Gecko pic- http://images.iop.org/objects/phw/news/12/10/14/Gecko.jpghttp://images.iop.org/objects/phw/news/12/10/14/Gecko.jpg Gecko pic 2- http://www.exoticpetswholesale.com/i//sm_blue_gecko02.jpghttp://www.exoticpetswholesale.com/i//sm_blue_gecko02.jpg Tooth brush pic - http://www.kosherimage.com/images/tbrush-4layflat.jpghttp://www.kosherimage.com/images/tbrush-4layflat.jpg Spring scale pic- http://www.enasco.com/prod/images/products/2A/VC131047l.jpghttp://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