Phonak, Warrenville, Ill, reports that the material used for all custom product shell colors in our digital manufacturing process have been certified to be nontoxic and non-skin-irritant according to independent laboratory biocompatibility testing. The company’s advancements in instrument-shell technology compliment its digital manufacturing and signal-processing developments.
In 2007, the companys introduced an advanced digital manufacturing process to all major custom production centers worldwide, which uses proprietary 3-D modelling software to create a virtual custom hearing instrument. The shell is automatically constructed layer by layer from medical-grade acrylic using computer-controlled UV light exposure.
All equipment is rigidly calibrated and operated according to strict process quality control standards. The dimensional precision and consistency of the hearing instrument shell is clearly a main benefit of the process, but an added benefit is the mechanical stability and biocompatibility of the shell material. For many years, custom hearing instrument shells were produced using a hand-poured manual process that resulted in shells that often varied in their mechanical properties.
Phonak has worked with producers of specialty medical grade UV-curable acrylics to develop and fine-tune eight colors of shell materials: pink, tan, cocoa, brown, red, blue, transparent, and white. Acrylic polymers are resistant to many biological and chemical agents and demonstrate excellent impact strength, dimensional stability, chemical and scratch resistance, biocompatibility, and clarity.
The shells received a rating of 0 on a 0-4 standard cytotoxicity scale, which is completely nontoxic. They also are rated 0-0.4 on a clinical dermal irritation test scale, which means they produce no or negligible skin reactions. These tests are compliant with ISO and FDA Good Laboratory Practice regulations.