Femtosecond lasers could improve cochlea implants say researchers

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Femtosecond lasers could create a better fit for cochlea implants. The lasers can shape the implant’s electrodes that make contact with the sensitive areas of the inner ear very accurately, thereby tailoring the implant to the individual and improving their hearing, say researchers.

The laser treats nickel-titanium shape memory alloys (NiTi-SMA) that are used for the implant’s electrodes. By using the laser to melt the surface of the NiTi-SMA electrodes it is possible to tailor the implant for the individual, according to researchers at the Laser Zentrum Hannover (LZH) where the work is being carried out. A close fit is necessary because the deeper the electrodes can be inserted into the cochlea in the inner ear, the better the fit and the better hearing can be.

The implant works by translating sound waves that are detected by a microphone into a series of electrical impulses. These impulses are sent by the electrodes down the auditory nerve in the inner ear. Normally tailoring the implant is difficult because it is only 300µm in diameter and has a curved surface.

About 95 per cent of those that have impaired hearing have an intact auditory nerve, which means they can have partial hearing. To enable hearing, cochlea implants, which are an electronic acoustic aid, take over the function of damaged sensory cells in the inner ear. Over 200,000 people worldwide could benefit from these artificial inner ears. By processing the electrodes to better fit the individual the deep implant can be achieved without damaging the inner ear’s basilar membrane.

The basilar membrane is covered by tiny sensory cells or hairs and it can only provide good hearing if it is not damaged. This means that the cochlea electrode must be inserted extremely carefully, to avoid damage to the membrane.

The LZH cochlea implant activities are funded by the German Federal Ministry of Education and Research, the interdisciplinary special research programme 599 of the German Research Foundation and the Hannover Medical School is also involved.