Artificial gills are hypothetical devices to allow a human to be able to take in
oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
from surrounding water. This is speculative technology that has not yet been demonstrated. Natural
gill
A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...
s work because most animals with gills are
thermoconformers (cold-blooded), so they need much less oxygen than a
thermoregulator (warm-blood) of the same size. However, there are exceptions, for example,
Opah,
Great White Shark
The great white shark (''Carcharodon carcharias''), also known as the white shark, white pointer, or simply great white, is a species of large Lamniformes, mackerel shark which can be found in the coastal surface waters of all the major ocea ...
and
Tuna. It is currently unclear if a practical artificial gill could be created; however, creating a biological gill with genetic engineering is theoretically possible.
Methods
Several potential methods exist for the development of artificial gills. One proposed method is the use of
liquid breathing with a
membrane oxygenator to solve the problem of
carbon dioxide
Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
retention, the major limiting factor in liquid breathing.
It is thought that a system such as this would allow for diving without risk of
decompression sickness
Decompression sickness (DCS; also called divers' disease, the bends, aerobullosis, and caisson disease) is a medical condition caused by dissolved gases emerging from Solution (chemistry), solution as bubbles inside the body tissues during D ...
.
An average
freediver needs 150ml of oxygen per minute while resting and 200-250ml of oxygen while swimming. Assuming the
mammalian diving reflex
The diving reflex, also known as the diving response and mammalian diving reflex, is a set of physiology, physiological responses to immersion that overrides the basic homeostasis, homeostatic reflexes, and is found in all air-breathing verteb ...
, some divers can reduce their heartbeat significantly, down to 14 bpm, radically reducing overall body oxygen demands even down to 100ml per minute. The amount of dissolved oxygen in water varies, but on average is 7.6mg per liter. At least of seawater per minute would have to be passed through the system, but this system would not work in
anoxic water. Seawater in tropical regions with abundant plant life contains of oxygen per liter of water.
[Fundamentals of Environmental Measurement](_blank)
/ref> These calculations are based on the dissolved oxygen content of water.
See also
* Extracorporeal membrane oxygenation
Extracorporeal membrane oxygenation (ECMO) is a form of extracorporeal life support, providing prolonged cardiac and respiratory system, respiratory support to people whose human heart, heart and human lung, lungs are unable to provide an adequa ...
*
References
External links
* History of attempts to develop artificial gills and the principles and problems involved.
*
*
'Like A Fish' Underwater Breathing System: Artificial Gills for U.S. Navy SEALs?
Artificial gills in fiction
(called a "hydrolung") in '' Tom Swift and the Electronic Hydrolung'', by Victor Appleton. It is a rebreather, fitted with a device that extracts oxygen from surrounding water.
{{DEFAULTSORT:Artificial Gills (Human)
Underwater diving medicine
Underwater breathing apparatus
Membrane technology