will alleviate the tissue reaction. Surface modiﬁcation of electrodes with anti-
appears to lessen the glial encapsulation, but some
gliosis is still present, so research in electrode surface modiﬁcation remains an
important topic for the realization of successful chronic neural electrodes.
The insertion of probes into the brain can be done quickly or slowly. Faster in-
sertion speeds and sharper needles result in less strain to the surrounding tissue.
This reduced strain may minimize tissue damage due to insertion, because pro-
cesses and cells near the electrode remain relatively undisturbed while those in
the electrode’s path are completely severed.
However, some investigators insist
that slower insertions lead to greater longevity in chronic recordings.
be because slow insertions allow cells and their processes time to be displaced and
moved, rather than impaled, by microelectrodes.
Insertion technique is far from
standardized in the neural interfacing ﬁelds, and no one technique may be best for
all MEMs devices, so insertion method will probably continue to be chosen on a
4.4 CONCLUDING REMARKS
MEMs devices hold immense promise for future neuroprosthetics and inves-
tigative biological studies. In vitro devices allow the observation of individual
cell types and their reactions to environmental stimuli; the small volumes used,
inexpensive materials, and ability to batch fabricate devices reduces the cost to
perform such studies. In vivo microdevices are less damaging to neural tissues
than larger devices, some can be batch fabricated, and most are electrically or
chemically active. Such devices may one day allow patients who have lost normal
neural function to regain it.
Neuronal interfacing technology is far from completely optimized, but new
developments are always reﬁning existing processes and opening new frontiers.
The implications for improved understanding of the nervous system and the
ability to improve patient quality of life are some of the strongest factors driving
strides being made towards seamless integration of sensor and actuator technol-
ogy with the human nervous system in the future.
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