When inserting cochlear implants, the main challenge facing otorhinolaryngologists (ORL) is to perform a nontraumatic insertion of the electrode array since it is vital to preserve the functional integrity of the undamaged parts of the cochlea. Electrode arrays must therefore be inserted into the cochlear duct, which is in the form of a spiral having very small radii of curvature (down to ~ 1.5 mm). The less damage caused by the procedure, the speedier the recovery, which greatly facilitates the rehabilitation phase following the operation.
To overcome this problem, we developed a noncontact fiber optic distance sensor based on frequency-domain low-coherence interferometry. This device instantly measures the distance from the end of the probe to the wall of the duct with a resolution of 30 µm over a 1 mm range. By using a special fiber featuring very low bending losses developed by INO, we are able to operate the probe even when coiled to a radius as small as 1.2 mm. The probe has very small dimensions (diameter = 140 µm), making it compatible with biomedical and industrial uses requiring a good degree of miniaturization