London, UK — Hearing aid manufacturer, Widex, is introducing stereo lithographic manufacturing technology to its UK production laboratory. The CAMISHA process will transform the way that customised digital in-the-ear (ITE) hearing aids are manufactured.

Until now, the final stages of manufacture of digital ITE aids have been based on a time-consuming manual process. An aid's outer shell is made from a cast taken from an impression of the patient's ear, which is sent to the laboratory by the hearing aid audiologist. This process suffers from fitting variability and lack of repeatability.

CAMISHA — Computer Aided Manufacturing of Individual Shells for Hearing Aids — is based around the latest computer modelling and laser technologies. Technicians now laser scan the ear canal impression and all the resulting data of the shape of the ear is transferred into a specially developed computer modelling software program. The lab technicians can then design an on-screen 3D computer model of the ideally shaped custom hearing aid, incorporating all the required miniature components in the available space.

The data for this model is then transferred to the stereo lithography apparatus (SLA), which uses a laser to build-up the shell layer-by-layer within a bath of liquid photoplastic acrylic material. The custom shells made by this new process have a superior quality and consistency, resulting in smaller sized and better fitting hearing aids for the user.

Widex holds the basic international patent for this new method for manufacturing hearing aid shells, which has only now become a reality thanks to the latest advances in scanner, computer modelling and materials technologies. Widexis licensing the technology to other hearing aid companies.

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