基板表面由於親疏水性的不同使液滴在水平基板上可發生自發
性移動現象。K. Yoshikawa 等人在2005 年於Physical Review Letters上發表了一篇有關自發移動液滴的論文，他們發現將油滴置於介面劑溶液底部的水平基板，在適當的邊界條件下，油滴自發性的擁有周期運動。在引起油滴移動的討論中他們藉靜態接觸角量測來討論基板因吸附介面劑所產生親疏水性的差異，但在事先吸附介面劑的基板上量測靜態接觸角將有遲滯角與介面劑脫附的問題，此類問題將影響著接觸角的量測。因此我們使用未事先吸附介面劑的基板與含有不同濃度的STAC 介面活性劑反應進行觀察，在靜態接觸角的量測過程我們發現含介面劑的試液於基板上有自疏水性的現象，並且藉由Langmuir等溫吸附與P. G. de Gennes所提出的反應關係擬合濃度0.1mM以下的液滴於基板上因反應而產生潤溼張力的改變趨勢，以指出介面劑在基板表面吸附後所增加的基板張力l 。
另外我們發現在介面劑溶液表面張力 下降迅速的區域，液滴置於乾淨玻璃基板上擁有自發移動的現象，因此我們進而藉由動態接觸角的量測發現此類因反應而產生的自發移動液滴將有一最小移動速度的要求。

Self-running of droplet is induced due to different hydrophilic properties on the surface of substrate that the droplet contact. This study was performed based on the study of Yoshikawa et. al, published in Physical Review Letter, volume 94, in 2005, exploring the behaviors of
self-running droplet. They have found that a droplet would present a pattern of regular rhythmic motion instead of random motion under certain boundary conditions properly designed. That they hypothesized the particular motions of droplet produced on the plates pretreated with adsorption surfactant for controlled hydrophilic conditions in respect to static contact angle, however, might neglect the affects of contact angle hysteresis and surfactant desorption, two important factors ought to be involved in the analysis of self-running droplet in question. In order to avoid these problems we substitute the clean plate with pretreated one.Moreover, we also changed pure water to the STAC surfactant solution. In our experiment we observed the autophobic phenomena on the surface of substrate. We combined the Langmuir isothermal adsorption and the reactive drop relation of P. G. de Gennes in order to fit the change of wetting tension between the concentrations of 0-0.1mM. From our fitting, the increasing of surface tension of solid-liquid interface according to increasing the STAC concentration of surface adsorption could be indicated.
We have also found that in the range where surface tension dropped rapidly, the test drop on the clean substrate has self-running phenomena. Furthermore, by measuring the dynamic contact angle it is found that the
self-running droplet requires a minimum velocity.

1. Yutaka Sumino, Nobuyuki Magome, Tsutomu Hamada, and
Kenichi Yoshikawa PRL 94, 068301 (2005)
2. E. F. Hare and W. A. Zisman, J. Phys. Chem. 59, 335,
(1955)
3. M. K.Chaudhury, G. M. Whitesides science 256 ,12 June
(1992)
4. Daniel, S., Chaudhury, M. K., and Chen, J. C., “Fast
Drop Movements Resulting from the Phase Change on a
Gradient Surface,” Science, 291, pp.633-636. ,(2001)
5. Fabrice Domingues Dos Santos and Thierry Ondarcuhu, PRL
75,16 (1995)
6. P.G.De Gennes, Rev. Mod. Phys. 57, 827 (1985)
7. P.G. de Gennes, Physica A 249 ,196-205 (1998)
8. Joesten, M. D.; Schaad, L. J. “Hydrogen Bonding”
Marcel Dekker:New. York,. (1974)
9. London,F. Trans Faraday Soc. 33, 8-26 (1937)
10.Landau and Lifshitz, Course of Theoretical Physics V.5
(1980)
11.Miller, Rei,”Dynamics of adsorption at liquid
interfaces :theory,experiment, application” ,Amsterdam
(1995)
12.Langmuir I, J.Am.Chem.Soc., 1917 ,39,1848 1906.
13.Arthur W.,A. P. Gast, “Physical Chemistry Of
Surfaces” (1982)
14.Weber, E. H. , Ann. Phys. (Poggendorff), 94, 447 (1855).
15.Thomson, J. (older brother of Lord Kelvin), Phil. Mag.,
Ser. 4, 10,330 (1855)
16.Marangoni, C. G. M. , Ann. Phys. (Poggendorff), 143,
337 (1871).
17.Paul Manneville, ”Dissipative structures and weak
turbulence”,Academic Press, (1990)
18.Wenzel, R. N. “Resistance of Solid Surfaces to
Wetting by Water,”Industrial and Engineering Chemistry,
28, pp.988-994.( 1936)
19.Cassie, A. B. D.and Baxter, S. “Wettability of Porous
Surfaces,”Transactions of the Faraday Society, 40, pp.
546-551.(1944)
20.國立成功大學碩士論文, 林宏文,“表面改質技術及其應用在冷
凝熱傳之實驗探討＂,民國94年7月
21.M.Z.-C. Hu et al Journal of Colloid and Interface
Science 270 229–241 (2004)
22.Israelachvili, Jacob N.,Intermolecular and surface
forces :with applications to colloidal and biological
systems ,Orlando. (1985)
23.http://www.uic.edu/classes/bios/bios100/lecturesf04am/le
ct02.htm
24.D. F. Evans,D. J. Mitchell, and B. W. Ninham, J. Phys.
Chem. 88,6344-6348(1984)
25.J.J. Cras, C.A. Rowe-Taitt, D.A. Nivens, F.S. Ligler,
Biosensors & Bioelectronics, 14, 683–688 (1999)
26.Gregory J. Besio,t Robert K. Prud’homme, and Jay B.
Benziger Langmuir, 4, No.1, (1988)
27.P.M. McGuiggan, R.M. Pashley Colloids and Surfaces, 27,
277-287 (1987)
28.Padday, J. F.“Wetting, spreading, and
adhesion :comprising papers (with discussions)
presented to a symposium”,Society of Chemical
Industry (1978)
29.Seok-Won Lee, Daniel Y. Kwok, and Paul E. Laibinis,
Physical Review E 65, 051602, (2002)
30.J. B. Brzoska, F. Brochard-Wyart, and F. Rondelez,
Langmuir,9,2220-2224, (1993)