Biomedical Engineering Reference
In-Depth Information
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CHAPTER 6
The Biomimetic Interface
between Brain and Electrodes:
Examples in the Design of
Neural Prostheses
6.1 The Nature of the Device-Brain Interface
Both neurons and electronic devices process information in the same all-
or-none impulses of electricity, though action potentials and logical states,
respectively. Electricity is carried as ion fluxes in the brain and as electron
currents in metal conductors in electronic circuits. As we have emphasized
throughout this text connecting any artificial device to cells, and relevant to this
section of this text, specialized tissues of the brain, presents a major bio-
compatibility problem. With respect to brain implants, it is clear that extreme
precision will be required in order to reach the target tissue and, additionally,
maintaining the implant in place with minimal damage being inflicted on
surrounding areas. Any attempt to use implantable devices to replace damaged
or non-functioning nerves is met with extreme stability and biocompatibility
problems associated with the tissue-device interface. However, it is possible
that novel interface technologies could potentially provide new therapies for
the restoration independence for severely disabled patients, a strategy offer
referred to as neural regeneration. Just as important, the regeneration approach
can have significant implications for neuroscience in that it facilitates a better
understanding of normal and pathological aspects in the functioning of the
central nervous system (CNS).
Prosthetic structures use electrical or optical stimulation to substitute for lost
biological function. The development of biomimetic prostheses began in 1958
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