Sensor Used in E-nose - The Electronic Nose Artificial Olfaction Technology - page 141

Chapter 6
Sensor Used in E-nose
6.1 Introduction
A sensor is a device that is used to measure physical quantity, and the opposite
device is the actuator, which converts signal into action and in transducer one form
of energy is electrical and therefore actuator and sensor are the other forms of the
transducer. Sensors provide us with a means of generating signals that can be used
as inputs to electronic circuits. Biosensors are analytical tools for the analysis of
biomaterial samples to gain an understanding of their biocomposition, structure,
and function by converting a biological response into an electrical signal. In
contrast with conventional bioarrays, biosensors allow the detection of molecular
interactions as they take place, without requiring auxiliary procedures, making
them highly attractive for biotechnological applications.
6.2 Measurement of Smell
Multiple useful roles are played by sensations of smell. It influences emotional
states, i.e., enthusiasm or attention. The sensation of smell allows the control of
food purity by word of warning beside bad food after remembering its association
with unpleasant odors; it also provides information about the family, or outsiders
in animals without skill of language; and last but not least it also activates salivary
and gastric emissions in response to pleasant odors. Unpleasant odors can evoke
symptoms.
Symptoms evocation, concentration disturbance, and productivity reduction are
the examples of unpleasant odors in the environmental air. Number of molecules
available in the concentration of the olfactory receptors is defined as odor sen-
sation dependence.
In the air, only volatile substances which may be associated with particular
matter have an odor. Sense of smell is capable to distinguish thousands of odors
but it is very difficult to categorize them based on their chemical structure