oxygenpermeable

Oxygenpermeable describes a material or interface that allows the diffusion of molecular oxygen (O2) through it. The concept is defined by the oxygen permeability of the material, often denoted as Dk, and in applications where thickness matters, by Dk/t, which incorporates the effect of film thickness on oxygen transmission.

In ophthalmology, oxygen permeability is a key parameter for contact lenses. The cornea receives most of its oxygen from the surrounding environment, so lenses with higher oxygen permeability help maintain corneal health and reduce hypoxic stress. Silicone-based and silicone hydrogel lenses are common examples of oxygen-permeable materials, enabling higher oxygen transmission compared with traditional hydrogel lenses. The Dk/t rating is routinely used to compare lenses for a given thickness.

Outside of eye care, oxygen-permeable membranes and films are used in various applications, including gas separation, packaging, wound dressings, and biomedical devices. Materials chosen for high oxygen transmission include certain silicone elastomers, fluorinated polymers, and select hydrogels, often balancing permeability with mechanical strength, optical clarity, or barrier properties.

Factors that influence oxygen permeability include the material’s diffusivity and solubility for oxygen, its thickness, temperature, and microstructure. Higher free volume and appropriate polymer chain mobility typically enhance O2 transport, while processing conditions and crosslinking can modify performance. Accurate assessment of oxygen permeability relies on standardized permeation measurements, often using permeation cells and reporting values in consistent units such as Dk or Dk/t.

See also: gas permeability, diffusion, polymer membranes.