Biomaterials for MEMS

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: [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.

www.panstanford.com

978-981-4241-46-5

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