Aesthetic prostheses currently exist to help those with deformities and surgical defects live without being stared at or appearing different from others. However, esthetic prostheses are exceptionally expensive and are affected by use which causes wear and color changes. These longevity issues must be dealt with to help users feel comfortable using their prostheses.

Executive Summary: Tong BME Design Award, BME 402

A composite polymer alternative to aesthetic finger prostheses.
Eduardo Enriquez, Rodrigo Umanzor, Nicholas Zacharias, Piper. Rawding, Laurie McKenna, Vincent Belsito

Advisor: Dr. Tracy Puccinelli
Client: Mr. Gregory Gion

Patients who undergo amputations or have limb disfigurements often experience severe psychological trauma from differences in physical appearances that can hinder them from feeling comfortable in society. Aesthetic prostheses function to help mask the appearance of disfigurements by restoring natural appearances, and ultimately improve the psychological and physical well-being of the patient. Current prostheses are composed of silicone due to its superior aesthetic qualities and compatibility with fabrication techniques, which allow for recreation of life-like appendages. These models, however, commonly fail from tearing, discoloration, and mold and fungal accumulation. Binding a polyurethane (PU) matrix onto silicone creates a composite prosthesis with enhanced mechanical properties, decreased porosity, and increased device longevity. Combining PU sheets with silicone prostheses has been attempted before, yet the impression technique used resulted in a weak bond interface, and did not protect against discoloration from ultraviolet exposure and skin oils, or fungal growth at the silicone surface.

The proposed PU coated silicone prosthesis compatible with compression molding fabrication would increase customer satisfaction by increasing product longevity. As mentioned previously, a prosthesis experiences significant discoloration and deterioration of physical integrity from daily use before the five year period insurances require before covering the cost of a new device; furthermore, these prosthetic devices can range from $2500 to $5000, and many patients cannot afford to cover the costs of a new device out of pocket without the help of insurance. The current product is a silicone aesthetic prosthesis that binds a thin layer of PU by priming the silicone surface and using an airbrush to apply the PU. This innovative technique reduces opacity of the PU layer and creates a thin protective film around the silicone prosthesis without affecting aesthetic properties and provides improved tear resistance, UV protection, and a smoother surface.

The design was evaluated through colorimetric and mechanical testing using UV exposure devices, MTS machines, and nano-tribometers to assess resistance to discoloration, quantify tear strength, bond strength, wear rate, and coefficient of friction. Peel strength testing indicated a potential for the bond between the two polymers provided by the primer to surpass the strength of the silicone matrix. Furthermore, tear strength was determined to be higher in PU coated samples relative to pure silicone samples. Coefficient of friction, wear rate, and resistance to discoloration from UV exposure are currently still being tested. On account of the enhanced mechanical properties provided by this approach, the design allows for a prosthetic device with greater longevity through a feasible method for the manufacturer and an investment with improved service life for the patient. The current market of aesthetic prosthetic devices are public consumers.

Preliminary Presentation

Composite Prothetic – Mid-Semester Poster

Final Report

Composite Prothetic – Final Poster

MSE Final Presentation