Cochlear implants for the deaf are the most successful neural prostheses; however, pitch perception remains relatively poor. Thin-film arrays can offer significant advantages over conventional wires by increasing pitch specificity, allowing greater pitch range, and reducing cost. However, in order for thin-film arrays to overtake wire-bundle technology they must be robust enough for safe insertion into the helical cochlea, stiff enough for deep insertion contain a means for placement and have a modiolus-hugging curl to position the sites close to receptor cells and reduce insertion trauma. To date, thin-film arrays have achieved high electrode count with reasonable robustness, but have not incorporated placement, curl and stiffness capabilities directly into the arrays. Instead, these attributes are achieved through molded or laminated carriers. Such carriers are applied using methods which are similar to the hand assembly techniques of wire-bundle arrays. However, unlike the wire-bundle arrays, it is very difficult and often impossible to apply these molds to the thin-film arrays without occluding electrode sites, tearing the arrays, or experiencing delaminating.
Researchers at the University of Michigan have invented methods of making thin-film cochlear electrode arrays with high site density, built in curl and integrated positioner. The array can be made out of all polymer and metal layers for a high degree of flexibility and robustness. Curvature can be built into the array with the addition of a curling layer placed partially or fully over the array during batch fabrication. This layer can be comprised of any material or combination of materials which can be added during batch fabrication and made to curl post fabrication. Examples of such layers could include but are not exclusive to stressed metal layers or conducting polymers. A channel can be integrated onto the array and with the aid of a passive/active stylet wire the channel can be utilized to straighten a curled array and/or fix a straight array for implantation. The stiffness of the channel can be tailored by changing its continuity with indents molded into the structure, slots cut out from it or a combination of both.
Applications and Advantages
- Cochlear Electrode Array
- Neural Probes
- Fluid Delivery
- Highly flexible and robust
- Fabrication process has fewer steps thus reducing production cost