Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.
Applied Biosystems SDS

Site Tools

  • AAAS
  • Subscribe
  • Feedback

Site Search

Search Advanced

Science 12 June 1992:
Vol. 256. no. 5063, pp. 1539 - 1541
DOI: 10.1126/science.256.5063.1539
Prev | Table of Contents | Next

Articles

How to Make Water Run Uphill

Manoj K. Chaudhury 1 and George M. Whitesides 2

1 Dow Corning Corporation, Midland, MI 48686
2 Department of Chemistry, Harvard University, Cambridge, MA 02138

A surface having a spatial gradient in its surface free energy was capable of causing drops of water placed on it to move uphill. This motion was the result of an imbalance in the forces due to surface tension acting on the liquid-solid contact line on the two opposite sides ("uphill" or "downhill") of the drop. The required gradient in surface free energy was generated on the surface of a polished silicon wafer by exposing it to the diffusing front of a vapor of decyltrichlorosilane, Cl3Si(CH2)9CH3. The resulting surface displayed a gradient of hydrophobicity (with the contact angle of water changing from 97° to 25°) over a distance of 1 centimeter. When the wafer was tilted from the horizontal plane by 15°, with the hydrophobic end lower than the hydrophilic, and a drop of water (1 to 2 microliters) was placed at the hydrophobic end, the drop moved toward the hydrophilic end with an average velocity of sim1 to 2 millimeters per second. In order for the drop to move, the hysteresis in contact angle on the surface had to be low (le10°).

Submitted on January 9, 1992
Accepted on April 15, 1992


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
From the Cover: Propagating waves of self-assembly in organosilane monolayers.
J. F. Douglas, K. Efimenko, D. A. Fischer, F. R. Phelan, and J. Genzer (2007)
PNAS 104, 10324-10329
   Abstract »    Full Text »    PDF »
A Generalized Approach to the Modification of Solid Surfaces.
D. Y. Ryu, K. Shin, E. Drockenmuller, C. J. Hawker, and T. P. Russell (2005)
Science 308, 236-239
   Abstract »    Full Text »    PDF »
A Reversibly Switching Surface.
J. Lahann, S. Mitragotri, T.-N. Tran, H. Kaido, J. Sundaram, I. S. Choi, S. Hoffer, G. A. Somorjai, and R. Langer (2003)
Science 299, 371-374
   Abstract »    Full Text »    PDF »
Surface-Responsive Materials.
T. P. Russell (2002)
Science 297, 964-967
   Abstract »    Full Text »    PDF »
Fast Drop Movements Resulting from the Phase Change on a Gradient Surface.
S. Daniel, M. K. Chaudhury, and J. C. Chen (2001)
Science 291, 633-636
   Abstract »    Full Text »
Alloying at Surfaces by the Migration of Reactive Two-Dimensional Islands.
A. K. Schmid, N. C. Bartelt, and R. Q. Hwang (2000)
Science 290, 1561-1564
   Abstract »    Full Text »
Light-Driven Motion of Liquids on a Photoresponsive Surface.
K. Ichimura, S. Oh, and M. Nakagawa (2000)
Science 288, 1624-1626
   Abstract »    Full Text »
Polymers Have "Intelligent" Surfaces: Polymer Surface Dynamics.
J.D. Andrade (1994)
Journal of Intelligent Material Systems and Structures 5, 612-618
   Abstract »


ADVERTISEMENT
Click Me!

ADVERTISEMENT
Click Me!

To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)