Scientists say they have succeeded in making water run uphill - at least in the laboratory.
To accomplish the gravity-defying feat, researchers reported Thursday they coated a small, silicon wafer with a film of water-repellent chemical applied progressively thicker from one edge to the other.The wafer was then tilted at a 15-degree angle, with the most water-repellent edge at the bottom and the least water-repellent edge at the top. When a water drop was placed on the wafer, it moved "uphill" away from the water-repellent region and toward the "water loving" region at a speed of 1 to 2 millimeters per second. A millimeter is equal to . 04 inch.
"The drop experiences a stronger force at its front (lower) end than at its back (upper) end. This difference of force is what causes the drop to move uphill," said Manoj Chaudhury of Dow Corning Corp. of Midland, Mich., who conducted the study with George Whitesides of Harvard University in Boston.
Practical applications of making water run uphill are "a little iffy at this time," Chaudhury says. But he thinks the phenomenon may prove useful in situations requiring water-repellent surfaces.