using hydrophilic/phobic materials
Materials now in labs can turn surfaces hydrophobic
or hydrophilic via applied voltages. The first
intended use is to shuttle water-based samples
around a chip-sized lab with multiple paths and chambers
that must be flooded and evacuated under external
That's a good idea and garners research money by hitting the hot buttons of
health (cheaper organic fluid testing) and terrorism
(compact and quick bad-stuff sniffers).
But the real good idea here is when the materials
can be made in large quantities and/or in an easily
applied coating. Then the hulls of boats can
be covered with this material. This may lead to
the following advances:
- Silent propulsion with no moving parts.
Just attract water to the hull at a point
(probably an area narrow in the direction of
travel, but the full width of the hull), then
cause it to become hydrophobic while making the
area just behind it hydrophilic. With successive
"waves" of this switching, the water
will move from the front of the boat to the
rear--the definition of propulsion. But no propellor or
impellor is required.
- Slipperier boats.
It is now well-known that certain patterns of
turbulence can actually make travel through fluid
more efficient. Dimples in golf-balls or scalloped
whale fins are common examples. A standing pattern
of hydrophilic/phobic areas on a hull may act as
golf ball dimples, breaking up the uniform surface
and leading to efficiency gains.
by Guy T. Schafer
(First published August 30, 2004)