Self‐bending hydrogel actuation for electrode shafts in cochlear implants

Abstract

A self‐bending electrode shaft for application in cochlear implants (CI) is presented. It is desired to reduce the distance between the electrode contacts and nerve cells in the modiolus of the inner ear. Therefore a coextrusion and overmolding device to fabricate a novel electrode shaft consisting of an eccentrically positioned hydrogel swelling actuator was established. Finite‐element‐analysis (FEA) was performed to analyse the self‐bending effect in relationship to the applied hydrostatic pressure. The mechanical actuation of a fabricated electrode shaft was tested in vitro by injection of water into the hydrogel. Curving of the electrode shaft was observed. Osmotic pressure in relation to the mass fraction of the swelling polymer inside the hydrogel was calculated.

Recent Advances in Cochlear Implant Electrode Array Design Parameters

“…Additionally, softer and more flexible electrode arrays are required to reduce the insertion trauma of the electrode array and postoperative fibrous tissue formation [ 37 ]. A hydrogel-based electrode array that can be bent-flexible when exposed to a saline solution (simulating the intracochlear fluid perilymph) was fabricated [ 38 ]. Here, a reliable hydrogel-driven self-bending CI electrode array was realized with a dummy electrode carrier made of silicon rubber and carbon nanotubes.…”

Decellularized equine carotid artery layers as matrix for regenerated neurites of spiral ganglion neurons

“…This is due to long current propagation in the perilymph, through which neurites cannot grow. 8 For a direct contact between neurons and electrodes, neurites need to grow and sprout out from the bony structures into the perilymph-filled gap and have to be guided to the electrode surface. In order to support the regeneration and guiding of neurites, possible guiding materials with different surface structures are under research, due to their influence on neurite outgrowth behavior and subsequently may improve the CI performance.…”

Engineering the Cell-Semiconductor Interface: A Materials Modification Approach using II-VI and III-V Semiconductor Materials

“…For implanted devices, maximizing device response and performance often involves minimizing the physical space between the device and the biosystem of interest. Minimizing this gap is particularly important in managing the function of neural interfaces, including optical and cochlear implants . In the case of osseointegrative implants, specifically those with a percutaneous element, modifying the texture and porosity of the implant at both the bone‐implant interface as well as the skin‐implant interface has offered significant improvements to both implant integration and general healing, with a reduced instance of infection and healthier tissue regrowth at the implant site .…”

“…Minimizing this gap is particularly important in managing the function of neural interfaces, including optical and cochlear implants. [ 5 ] In the case of osseointegrative implants, specifi cally those with a percutaneous element, modifying the texture and porosity of the implant at both the bone-implant interface as well as the skin-implant interface has offered signifi cant improvements to both implant integration and general healing, with a reduced instance of infection and healthier tissue regrowth at the implant site. [ 6 ] The demonstrable response of cells and recovering tissue to implant texture and morphology suggests that in addition to specifi c chemical passivation and modifi cation, topographic variation in substrate preparation can offer this desired improvement to the device-biosystem interface.…”