Hydrogel is a network of polymer chains that are water-insoluble, sometimes found as a colloidal gel in which water is the dispersion medium. Hydrogels are superabsorbent (they can contain over 99% water) natural or synthetic polymers. Hydrogels possess also a degree of flexibility very similar to natural tissue, due to their significant water content. In general, a colloid or colloidal dispersion is a substance with components of one or two phases, a type of mixture intermediate between a homogeneous mixture (also called a solution) and a heterogeneous mixture with properties also intermediate between the two. ... In optical filters and theatrical lighting a color gel is a transparent or translucent colored panel used to change the color of transmitted light. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... A polymer is a long, repeating chain of atoms, formed through the linkage of many molecules called monomers. ...

Common uses for hydrogel are

• currently used as scaffolds in tissue engineering. When used as scaffolds, hydrogels may contain human cells in order to repair tissue.
• environmentally sensitive hydrogels. These hydrogels have the ability to sense changes of pH, temperature, or the concentration of metabolite and release their load as result of such a change.
• as sustained-release delivery system
• provide absorption,desloughing and debriding capacities of necrotics and fibrotic tissue.
• hydrogels that are responsive to specific molecules, such as glucose or antigens can be used as biosensors as well as in DDS.
• In disposable diapers where they "capture" urine, or in sanitary towels
• contact lenses (silicone hydrogels, polyacrylamides)
• medical electrodes using hydrogels composed of cross linked polymers (polyethylene oxide, polyAMPS and polyvinylpyrrolidone)

Other, less common uses include A biosensor is a device for the detection of an analyte that combines a biological component with a physicochemical detector component. ... It has been suggested that this article or section be merged with Training pants. ... This article or section is in need of attention from an expert on the subject. ... A sanitary towel (U.K.) or sanitary napkin (U.S.) is an absorbent piece of material worn by a woman while she is menstruating, to absorb the flow of blood from the vagina. ... A pair of contact lenses, positioned with the concave side facing upward. ... Silicones (more accurately called polymerized siloxanes or polysiloxanes) are inorganic-organic polymers with the chemical formula [R2SiO]n, where R = organic groups such as methyl, ethyl, and phenyl. ... Polyacrylamide is an acrylate polymer formed from acrylamide subunits that is readily cross-linked. ... Vulcanization is an example of cross-linking. ... Polyethylene glycol (PEG) and polyethylene oxide are polymers of ethylene oxide. ... PolyAMPS, or poly(2-acrylamido-2-methyl-1-propanesulfonic acid), is an organic polymer. ... PVP (polyvinyl pyrrolidone, povidone, polyvidone) is a water-soluble polymer made from the monomer n-vinyl pyrrolidone: The monomer is carcinogenic and is extremely toxic to aquatic life. ...

• breast implants
• granules for holding soil moisture in arid areas
• dressings for healing of burn or other hard-to-heal wounds. Wound GEL are excellent for helping to create or maintain environment.
• reservoirs in topical drug delivery; particularly ionic drugs, delivered by iontophoresis (see ion exchange resin)

Common ingredients are e.g. polyvinyl alcohol, sodium polyacrylate, acrylate polymers and copolymers with an abundance of hydrophilic groups. A breast implant is a prosthesis used to enlarge the size of a womans breasts (known as breast augmentation, breast enlargement or augmentation mammoplasty) for cosmetic reasons; to reconstruct the breast (e. ... Loess field in Germany Surface-water-gley developed in glacial till, Northern Ireland Technically, soil forms the pedosphere: the interface between the lithosphere (rocky part of the planet) and the biosphere, atmosphere, and hydrosphere. ... This article includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ... Superficial bullet wounds In medicine, a wound is a type of physical trauma wherein the skin is torn, cut or punctured (an open wound), or where blunt force trauma causes a contusion (a closed wound). ... Iontophoresis is a non-invasive method of propelling high concentrations of a charged substance, normally medication or bioactive-agents, transdermally by repulsive electromotive force using a small electrical charge applied to an iontophoretic chamber containing a similarly charged active agent and its vehicle. ... Ion exchange resin beads An ion exchange resin is an insoluble matrix (or support structure) normally in the form of small (1-2 mm diameter) beads, usually white or yellowish, fabricated from an organic polymer substrate. ... Chemical structure of polyvinyl alcohol Polyvinyl alcohol (PVOH, PVA, or PVAL) is a water-soluble synthetic polymer. ... Sodium polyacrylate also named acrylic sodium salt polymer or simply ASAP (repeating unit: -CH2-CH(CO2Na)- ) is a crosslinked acrylic acid polymer sodium salt, invented by Robert Niles Bashaw, Bobby Leroy Atkins and Billy Gene Harper in the Basic Research Laboratory of the Dow Chemical Company. ... Acrylate monomers are esters that contain vinyl groups, that is, two carbon atoms double bonded to each other, directly attached to the carbonyl carbon. ... A heteropolymer, also called a copolymer, is a polymer formed when two different types of monomer are linked in the same polymer chain. ... The adjective hydrophilic describes something that likes water (from Greek hydros = water; philos = friend). ...

See also

• Hydrocolloid

f Hydrocolloids are used in some skin care products A hydrocolloid is defined as a colloid system were the colloid particles are disperesed in water. ...

External links

Look up presbyopia in Wiktionary, the free dictionary.

• ReVision Optics, Presbyopia Correction Research