There are a number of characteristics of skin that are biologically and biomedically important and interesting. For example, skin serves as the primary barrier that prevents toxic compounds from entering the body and that keeps essential compounds from leaving the body.
Skin is also essential in thermoregulation and for sensing external stimuli from the environment.
From a biomedical engineering perspective, there are two applications where knowledge of the structure and function of skin are important. The development of artificial or replacement skin for treatment of burn victims is perhaps the most obvious. Another application that has currently received interest is the development of transdermal drug delivery processes whereby a pharmaceutical compound is delivered to the bloodstream at a controlled rate by diffusive transport across a section of the skin. These two types of applications provide excellent examples of how the chemical engineering principles of mass transfer with chemical reaction in complex media can be applied to the analysis of biomedical engineering problems. The traditional methods for drug delivery such as intravenous injections and oral administration have several disadvantages due to the transient nature of the delivery method and to metabolic degradation in the stomach.