Browsing by Author "Wade, Scott"

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    Effect of embedded optical fibres on the mechanical properties of cochlear electrode arrays
    (Elsevier Ltd., 2016-02) Carland, Emma; Stoddart, Paul; Cadusch, Peter; Fallon, James; Wade, Scott
    Incorporating optical fibres in cochlear electrode arrays has been proposed to provide sensors to help minimise insertion trauma and also for the delivery of light in optical nerve stimulation applications. However, embedding an optical fibre into an electrode array may change its stiffness properties, which can affect the level of trauma during insertion. This report uses measurements of buckling and deflection force to compare the stiffness properties of a range of cochlear electrode arrays (Nucleus straight array, rat array, cat array and guinea pig array) with custom arrays containing an embedded optical fibre. The cladding diameters of the optical fibres tested were 125 µm, 80 µm and 50 µm. The results show that the stiffness of the optical-fibre-embedded arrays is related to the diameter of the optical fibre. Comparison with wired arrays suggests optical fibres with a diameter of 50 µm could be embedded into an electrode array without significantly changing the stiffness properties of the array
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    Infrared neural stimulation fails to evoke neural activity in the deaf guinea pig cochlea.
    (Elsevier, 2015-03) Thompson, Alexander; Fallon, James; Wise, Andrew; Wade, Scott
    At present there is some debate as to the processes by which infrared neural stimulation (INS) activates neurons in the cochlea, as the lasers used for INS can potentially generate a range of secondary stimuli e.g. an acoustic stimulus is produced when the light is absorbed by water. To clarify whether INS in the cochlea requires functioning hair cells and to explore the potential relevance to cochlear implants, experiments using INS were performed in the cochleae of both normal hearing and profoundly deaf guinea pigs. A response to laser stimulation was readily evoked in normal hearing cochlea. However, no response was evoked in any profoundly deaf cochleae, for either acute or chronic deafening, contrary to previous work where a response was observed after acute deafening with ototoxic drugs. A neural response to electrical stimulation was readily evoked in all cochleae after deafening. The absence of a response from optical stimuli in profoundly deaf cochleae suggests that the response from INS in the cochlea is hair cell mediated.
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    Measurement of forces at the tip of a cochlear implant during insertion.
    (IEEE, 2014-01-02) Wade, Scott; Fallon, James; Wise, Andrew; Shepherd, Robert; James, Natalie; Stoddart, Paul
    An optical fiber based sensor has been developed to measure the forces at the tip of an electrode array during insertion into the cochlea. The sensor, utilizing optical fiber Bragg grating technology, was incorporated into a custom designed Pt-banded electrode array for guinea pigs. In vivo experiments were undertaken in which forces at the tip of the array were measured in real time during the insertion. Data was obtained for maximum insertion forces of up to 254 mN. Histology was performed on the excised cochleae with the sensors fixed in position to evaluate the level of insertion trauma. The insertion experiments demonstrated a clear correlation between applied force and collateral tissue damage.