Chapter Four
MEMS in the Nervous System
Sharon Norman
and Ravi Bellamkonda
Bioengineering Program, School of Electrical and Computer Engineering,
Atlanta GA 30332, USA. E-mail:
Wallace H Coulter Department of Biomedical Engineering at Georgia In stitute of
Technology and Emory School of Medicine, Atlanta GA 30332-0535, USA
Seamless interfacing with the human nervous system is likely to have significant
implications for enhanced understanding of its function, as well as exciting ther-
apeutic potential. However, it is important to recognize the biological landscape
setting the design criteria for any engineering interface to the nervous system. The
nervous system of mammalian species is incredibly complex, but can be divided
into two basic parts, central and peripheral. The central nervous system (CNS) is
composed of the brain and spinal cord, while the peripheral system (PNS) consists
of sensory, motor, and pain fibers that connect the body’s extremities to the spinal
cord and the brain. Therefore there exists a neuroanatomical map that is intricate as
well as a neurochemical map that has great, micron level topographical specificity
that any sensor would have to accommodate. Essentially, the brain has a high cell
density and particular regions of the cortex are responsible for specific functions.
The cortex is a striated structure, and each layer contains different types of
cells that code for different functions. The simplest unit of the nervous system
is the neuron, which has a cell body, or soma, and two types of processes, called
dendrites and axons. The primary mode of communication” between neurons
involves electrical signals, also known as action potentials, that propagate down
axons to connect with the processes or somas of other neurons. These action
potentials are the main means of communication within the nervous system and
are commonly initiated by the release of neurotransmitters from surrounding
neurons. Therefore from an analytical perspective, electrical and chemical signals
are the information carriers in the nervous system and they are dispersed with
great regional specificity throughout the X, Y, Z and temporal space of the nervous
system. Any sensor/actuator system that interfaces to the nervous system, then, is
judged by how efficiently it is able to monitor and influence this spatio–temporally
organized information processing system.
Biomaterials for MEMS, Edited b y M. Chiao and J.-C. Chiao
Copyright © 2011 by Pan Stanford Publishing Pte. Ltd.
SO13997_text.indd 73SO13997_text.indd 73 26/01/2011 3:50 PM26/01/2011 3:50 PM

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