New manufacturing processes improve cochlear implants

Researchers have developed designs for higher-performance electrodes which could substantially improve sound perception in the next generation of cochlear implants.

AUSTRALIAN academic and commercial researchers have developed designs for higher-performance electrodes which could substantially improve sound perception in the next generation of cochlear implants.

The work was carried out by University of Melbourne Research Fellow Dr Carrie Newbold, the HEARing Cooperative Research Centre (HEARing CRC) and Cochlear Limited.

The research, which has been ongoing since 2001, looks at less intrusive, slim electrode designs, the use of new biomaterials and manufacturing techniques to produce electrodes with higher capacity for information transmission.

Dr Newbold’s research into the interactions between the cochlear implant’s electrodes and the tiny nerve cells of the cochlear has allowed the collaborative effort to explore ways to improve the electrodes’ efficiency, and thus boost the transmission of the sound information through the electrode array.

Dr Newbold said the manufacture of small devices is a challenge.

“The current design of cochlear implant uses 22 individual electrodes, spaced along the electrode array to stimulate different nerve cell groups located along the cochlea,” she said.

Given the diminutive sizes of the electrodes, their connecting wires are even thinner (around a quarter the thickness of a strand of human hair). This necessitates hand assembly, limiting production numbers.

The delicate membranes and internal structures in the cochlea present an additional challenge during the implant process. The new designs address these challenges by changing the physical characteristics of the electrode array and thus making it easier to surgically insert the device with minimum risk of damage.

The researchers are also looking at the potential application of new conductive polymers for improving hearing stimulation in the cochlear. These plastics may supplement or replace current electrode materials, since they are more efficient with electricity, and are also less brittle.