Where did I Put My Nose?

Location:

Concepts Shown:

artificial body parts, biocompatibility, silicone

Equipment:

slide of artificial eye, ear, and nose. Artificial ear, transparency of silicone properties.

Procedure:

Science:

Silicone is the most common material to form prothesis. Dow Corning MDX-4-4210 Clean Grade Elastomer is often used. An elastomer results from unkinking polymer chains. This produces a material with a large elastic strain: Uses: Parts: ears nose fingers toes Coatings: Encapsulation of electronic components of biomedical devices Movies: Latex was commonly used for special effects makeup. For example, an actor might wear an artificial nose to portray a character. When movie and television productions switched to high resolution film, the latex costume make-up could be easily seen. To correct this problem, film makers turned to silicone. It is now used in all productions that require extensive make up. Example: Star Trek: The Next Generation. It is a room temperature vulcanizing elastomer. Vulcanization is the process of adding sulfur to rubber to crosslinking elastomer chains. The following properties make silicone an ideal material: � Essentially inert � Low shrinkage rubber which cures at room temperature � Unlimited thick section cure � Excellent dielectric properties � Heat accelerable cure � Physical and electrical stability � High elongation Biocompatibility: Silicone was tested for biological response by taking properly cured sections and implanting into intramuscular tissue and evaluating them after seven days and after 3 months. A mild reaction consisting of connective tissue proliferation with an associated minimal mononuclear inflammatory cell response. Comments: This is a great way to spark interest in materials science. It grabs people�s attention. Good for introductory class or tour groups. Side Note: There has been a tremendous amount of controversy about silicone breast implants. Breast implants differ from ears and nose implants because silicone is in liquid form (not cured). This liquid is placed in polymer bags and placed into the body. If the liquid can escape from the bag it results in a biological reaction. The body does not react to cured silicone because it has time to respond. Liquid proceeds at a much faster rate than a solid would. There are two reasons why a bag might rupture. First of all, the material for the liner could be defective and degrade in the body. This would cause an eventual leakage. The second reason is that the surgeon might tear the bag with his/her scalpel during the operation. It is unresolved which is the cause of the leakage. Yet, silicone liquid is unsafe and saline and other implants are now being used. [eq].

References:

Author:
Marcia Muller
Credits:


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