Biomedical Engineering Reference
In-Depth Information
been encouraging the study, a lot of groups around the world are eagerly
untertaking research in this area.
In this section, we review recent developments in nerve electrode techno-
logy, including the work of our research group.
4.8.2
The Nerve Electrode (Handmade)
An Electrode for a Nerve Bundle.
First, nerve electrodes for compound
signals are shown:
•
the wire electrode [153]
•
the cuff electrode [154]
•
the collagen electrode [155]
All of these can be used chronically, and Fig. 4.39 shows the schematics
of the wire electrode and the cuff electrode.
Wire electrodes made from various metals, such as SS, Pt-Ir, and silver,
have been used for long-term measurements. Their impedance is determined
by the dimensions and the surface status of the exposed area (for example,
whether or not platinum black is deposited). By adapting their impedance,
they can be used for measurement of single nerve fibers or a small number
of fibers. A wire electrode and nerve bundle are embedded in two-component
silicone rubber for fixation [153].
Also, cuff electrodes are widely used for recording from and stimulating
peripheral nerves. They fix a nerve bundle by covering it with their silicone
tubes. The two wire electrodes arranged inside the tube work as electrodes.
Collagen electrodes were developed by Ninomiya and co-workers, for cir-
culation physiological research. The nerve signal is measured through the skin
electrode, which consists of collagen fiber. Stable long-time measurements can
be realized, because the nerve bundle and the metal electrode do not contact
each other directly [155].
In general, the influence of the connective tissue or the exudate from the
surrounding tissue limits the recording time of these kinds of electrodes for
nerve bundles.
Fig. 4.39. a
A wire electrode (embedded in two-component silicone rubber for
fixation).
b
A cuff electrode (fixed to the nerve bundle by a silicone tube).
N
:
Nerve bundle
