09-05-2012, 01:51 PM
Artificial Neural Networks
ELECTRONIC_NOSE.pdf (Size: 289.11 KB / Downloads: 31)
INTRODUCTION
The electronics field is developing at a fast rate. Each
day the industry is coming with new technology and
products. The electronic components play a major role in
all fields of life. The scientists had started to mimic the
biological world. The development of artificial neural
network (ANN), in which the nervous system is
electronically implemented is one among them.
THE BIOLOGICAL NOSE
To attempt to mimic the human apparatus,
researchers have identified distinct steps that characterize
the way humans smell. It all begins with sniffing, which
moves air samples that contain molecules of odors past
curved bony structures called turbinate. The turbinate
create turbulent airflow patterns that carry the mixture of
volatile compounds to that thin mucus coating of the
nose’s olfactory epithelium, where ends if the nerve cells
that sense odorants.
ELECTRONIC NOSE PRINCIPLES
Enter the gas sensors of the electronic nose. This
speedy, reliable new technology undertakes what till now
has been impossible – continuous real monitoring of odor
at specific sites in the field over hours, days, weeks or even
months.
An electronic device can also circumvent many other
problems associated with the use of human panels.
Individual variability, adaptation (becoming less sensitive
during prolonged exposure), fatigue, infections, mental
state, subjectivity, and exposure to hazardous compounds
all come to mind. In effect, the electronic nose can create
odor exposure profiles beyond the capabilities of the
human panel or GC/MS measurement techniques.
Sensing an odorant
In a typical electronic nose, an air sample is pulled
by a vacuum pump through a tube into a small chamber
housing the electronic sensor array. The tube may be
made of plastic or a stainless steel. Next, the sample–
handling unit exposes the sensors to the odorant,
producing a transient response as the VOCs interact with
the surface and bulk of the sensor’s active material.
(Earlier, each sensors has been driven to a known state by
having clean, dry air or some other reference gas passed
over its active elements.) A steady state condition is
reached in a few seconds to a few minutes, depending on
the sensor type.
ELECTRONIC_NOSE.pdf (Size: 289.11 KB / Downloads: 31)
INTRODUCTION
The electronics field is developing at a fast rate. Each
day the industry is coming with new technology and
products. The electronic components play a major role in
all fields of life. The scientists had started to mimic the
biological world. The development of artificial neural
network (ANN), in which the nervous system is
electronically implemented is one among them.
THE BIOLOGICAL NOSE
To attempt to mimic the human apparatus,
researchers have identified distinct steps that characterize
the way humans smell. It all begins with sniffing, which
moves air samples that contain molecules of odors past
curved bony structures called turbinate. The turbinate
create turbulent airflow patterns that carry the mixture of
volatile compounds to that thin mucus coating of the
nose’s olfactory epithelium, where ends if the nerve cells
that sense odorants.
ELECTRONIC NOSE PRINCIPLES
Enter the gas sensors of the electronic nose. This
speedy, reliable new technology undertakes what till now
has been impossible – continuous real monitoring of odor
at specific sites in the field over hours, days, weeks or even
months.
An electronic device can also circumvent many other
problems associated with the use of human panels.
Individual variability, adaptation (becoming less sensitive
during prolonged exposure), fatigue, infections, mental
state, subjectivity, and exposure to hazardous compounds
all come to mind. In effect, the electronic nose can create
odor exposure profiles beyond the capabilities of the
human panel or GC/MS measurement techniques.
Sensing an odorant
In a typical electronic nose, an air sample is pulled
by a vacuum pump through a tube into a small chamber
housing the electronic sensor array. The tube may be
made of plastic or a stainless steel. Next, the sample–
handling unit exposes the sensors to the odorant,
producing a transient response as the VOCs interact with
the surface and bulk of the sensor’s active material.
(Earlier, each sensors has been driven to a known state by
having clean, dry air or some other reference gas passed
over its active elements.) A steady state condition is
reached in a few seconds to a few minutes, depending on
the sensor type.