Biomedical Engineering Reference
In-Depth Information
FIGURE 6-42
Auditory brainstem
implant. (a) Cross
section through the
ear showing implant
position. (b) Insertion
of penetrating
electrode array.
[Adapted from
(Graham-Rowe
2004).]
An implant developed by Bob Shannon of the House Ear Institute is expected to
perform better as it consists of eight electrodes of different lengths that are inserted into
the brain stem, as shown in Figure 6-42, and will be able to stimulate several bundles
of nerves individually. These electrodes should be able to excite different regions of the
cochlear nucleus that respond to and process signals of different frequencies.
6.10.1 Electrodes
Surface ABI electrode arrays consist of a number of closely spaced disk or button-shaped
elements embedded in a silicon carrier fixed to a fabric mesh for strength. Penetrating
ABIs typically consist of needle microelectrodes, which are carefully designed because if
they are too sharp they cut cells and if they are too blunt they crush them (Graham-Rowe,
2004). Examples of these two electrode types are shown in Figure 6-43.
FIGURE 6-43
Examples auditory
brainstem electrode
arrays.
(a) Penetrating type.
(b) Surface type.
