Israeli inventor Alon Bodner has developed an
underwater breathing system that literally squeezes oxygen
directly from seawater, doing away with the need
for tanks.
Called “LikeAFish,” the battery-powered artificial
gill extracts small amounts of dissolved air that exist
in water to deliver it to the diver. It uses a high-speed
centrifuge to lower the pressure of seawater in a small
sealed chamber. The dissolved air escapes back into a
gaseous state — much as carbon dioxide is liberated
from a soft drink when you pop the bottle cap. The
air is then transferred into a small impermeable light
weight bag, for the diver to breathe.
Bodner’s system must circulate 200 quarts of water/
minute to accommodate the breathing needs of an
average diver, he says. A one-kilo battery should be able
to supply a diver with one hour of dive time.
Today, his system exists as a laboratory model with
approved European patents and US patents pending.
He eventually plans to reduce the size of the apparatus
to a small, lightweight vest for divers.
Some people like Mike Rowley, a British Sub Aqua
Club Instructor, aren’t so sure it will serve divers.
Bodner makes the assumption that a closed-circuit rebreather
diver will use a quart of oxygen per minute.
However, with heavy swimming against a strong current
this can require at least 3.5 quarts/ minute. Says
Bodner, the device will need “some form of reserve
capacity to enable it to cope with lengthy periods of
high oxygen metabolism.” And that would mean a
much larger device, perhaps too large to make it practical
for divers.
Craig Billingham, a technical diving instructor, says
to get the time one gets from a rebreather or twin
tanks, you will need a lot of batteries. “Also batteries
and seawater don’t mix. It isn’t a case of if it leaks but
when.”
Bodner says that it would be undesirable to use the
system if the water lacks oxygen or is polluted. A small
compressed air tank built into the system could act as
a reserve in case of battery failure. He says a fully functional
prototype is about two years away.
By Lakshmi Sandhana, BBC News, January 31, 2006