In an ever-developing world, where electronic devices are duplicating every
other sense of perception, the sense of smell is lagging behind. Yet, recently,
there has been an urgent increase in the need for detecting odours, to replace
the human job of sensing and quantification.
of the most important applications fall in the category where human beings cannot
afford to risk smelling the substance. Other important applications are continuous
monitoring, medical applications, etc. These applications allow man to perform
tasks that were once considered impossible.The fast
paced technology has helped develop sophisticated devices that have brought the
electronic nose to miniature sizes and advanced capabilities. The trend is such
that there will be accurate, qualitative and quantitative measurements of odour
in the near future.
Living beings interact with the surrounding environment
through particular interfaces called senses, which can be divided in two groups:
those detecting physical quantities and those detecting chemical quantities.
interfaces (that deals with acoustic, optic, temperature and mechanic interaction
mechanisms) are sufficiently well known and a wealth of successful studies to
construct their artificial counterparts has been done in the past years. On the
other side the chemical interfaces (bio transducers of chemical species in air:
olfaction, and in solution: taste) even if well described in literature, present
some aspects of their physiological working principal that are still unclear.
It has also to be remarked a psychological difference, in human beings, between
the two groups. Indeed the information from the physical senses can be adequately
elaborated, verbally expressed, firmly memorized and fully communicated. On the
contrary chemical information, coming from nose and tongue, are surrounded by
vagueness and this is reflected in the poor description and memorization capacity
in reporting olfactory and tasting experiences. Chemical information is of primary
importance for the major part of the animals; for many of them, indeed, chemistry
is the unique realm of which they are concerned, while for human beings evolution
has enhanced about exclusively the physical interfaces, leaving little care of
the chemical interface, if we exclude unconscious acquisition and side behaviours.
For these intrinsic difficulties toward the understanding of the nature of these
senses for many years only sporadic research on the possibility of fabricating
artificial olfactory systems were performed. Only at the end of the eighties a
new and promising approach was introduced. It was based on the assumption that
an array of non-selective chemical sensors, matched with a suitable data processing
method, could mimic the functions of olfaction.
the past decade, electronic nose instrumentation has generated much interest internationally
for its potential to solve a wide variety of problems in fragrance and cosmetics
production, food and beverages manufacturing, chemical engineering, environmental
monitoring, and more recently, medical diagnostics and bioprocesses. Several dozen
companies are now designing and selling electronic nose units globally for a wide
variety of expanding markets. An electronic nose is a machine that is designed
to detect and discriminate among complex odours using a sensor array. The sensor
array of consists of
broadly tuned (non-specific) sensors that are treated
with a variety of odour-sensitive biological or chemical materials.
An odour stimulus
generates a characteristic fingerprint (or smell-print) from the sensor array.
Patterns or fingerprints from known odours are used to construct a database and
train a pattern recognition system so that unknown odours can subsequently be
classified and identified. Thus, electronic nose instruments are comprised of
hardware components to collect and transport odours to the sensor array - as well
as electronic circuitry to digitise and stored the sensor responses for signal
Digital Audio Broadcasting
Digital Audio's Final Frontier-Class D Amplifier
Digital Light Processing
Digital Subscriber Line (DSL)
Digital Video Editing
Direct to home television (DTH)
Direct Current Machines
Distributed Integrated Circuits
<<Back To Electronics Seminars