Membrane filters air — A wisp of synthetic membrane, only a thousandth of an inch thick, may hold the answer to a simple system for supplying submarines with air drawn from the water around them…. The “aqua-hamster” penned in a submerged plastic tank, shown on this week’s cover, is kept alive by an artificial “gill,” a piece of the synthetic membrane stretched across the top, bottom and two sides of its underwater home.… The “gill” extracts air from the surrounding water, while resisting the passage of the liquid. — Science News Letter, November 7, 1964
Membranes are challenging to manufacture on a large scale, so today’s submarines use oxygen tanks or generators, which use electricity to extract oxygen from water. Underwater labs like Florida International University’s Aquarius are fed oxygen through an umbilical cord. In October, Danish scientists synthesized a crystal that sucks oxygen from air and water and releases it later. A few grains can store enough oxygen for a breath, making it an ideal candidate for underwater breathing.