Fig. 11

Example of multi-layered wound dressing system. Schematic representation of dual-layered wound dressing system, Winter’s Composite. Includes a hydrophilic, permeable base foam dressing layer (Bottom, black) covered by a hydrophobic, semi-permeable dressing layer (Top, green). Depicted in the composite dressing is the combined effects of a permeable and semi-permeable dressing, where all fluids and cells/bacteria can pass through the permeable foam base, but liquid water (and other liquids such as serous exudate) in addition to cells/bacteria get stuck within the permeable foam layer because they cannot pass through into the semi-permeable dressing on superficial surface. However, the semi-permeable layer still allows some removal of water through evaporation, where water vapor is allowed to pass but not liquid water. This combination, known as Winter’s composite, creates a permeability gradient and can aid in exudative removal in mildly exudative wounds, upon dressing changes, due to the absorptive hydrophilic foam. Oxygen molecule depicted as small blue circle. Carbon dioxide molecule depicted as small purple circle. Bacteria depicted as green organism. Water is depicted as larger blue circle. Black arrows depict movement through dressing material. Thicker arrows depict ability to evaporate into ambient environment. Red arrow accompanied by red “X” depicted lack of transport through material. Black-dashed arrow depicts that liquid water does not transport but water vapor still can. Created using www.biorender.com software