[1] Autumn K, Liang Y A, Hsieh S T, Zesch W, Chan W P, Kenny T
W, Fearing R and Full R J 2000 Nature 405 681

[2] Huber G, Gorb S N, Spolenak R and Arzt E 2005 Biol.
Lett. 1 2

[3] Autumn K, Sitti M, Liang Y A, Peattie A M, Hansen W R,
Sponberg S, Kenny T W, Fearing R, Israelachvili J N and Full R J
2002 Proc. Natl. Acad. Sci. U.S.A. 99 12252

[4] Arzt E., Gorb S and Spolenak R 2003 Proc. Natl. Acad.
Sci. U.S.A. 100 10603

[5] Chen S H and Gao H J 2007 J. Mech. Phys. Solids
55 1001

[6] Chen S H and Soh A K 2008 J. R. Soc. Interface
5 373

[7] Glassmaker N J, Jagota A, Hui CY and Kim J 2004 J. R.
Soc. Interface 1 23

[8] Majidi C, Groff R E, Maeno Y, Schubert B, Baek S, Bush B,
Maboudian R, Gravish N, Wilinson M, Autumn K and Fearing R S 2006
Phys. Rev. Lett. 97 076103

[9] Kim S, Aksak B and Sitti M 2007 Appl. Phys. Lett.
91 221913

[10] Aksak B, Sitti M, Cassell A, Li J, Meyyappan M and Callen
P 2007 Appl. Phys. Lett. 91 061906

[11] Yao H and Gao H 2006 J. Mech. Phys. Solids 54
1120

[12] Wang P, Yang H J, Wang H B, Li H, Wang X Y, Wang Y, Lu J
H, Li B, Zhang Y and Hu J 2008 Chin. Phys. Lett. 25 2407

[13] Johnson K L, Kendall K and Roberts A D 1971 Proc. R.
Soc. London A 324 301

[14] Yoon E S, Singh R A, Oh H J and Kong H 2005 Wear
259 1424