Applications and Perspectives of Bioelectronic Nose - Bioelectronic Nose: Integration of Biotechnology and Nanotechnology - page 267

14.1.5 Other Applications

There are various other fields where bioelectronic noses can be effectively utilized
besides the examples that have been previously discussed. First of all, the bioelec-
tronic nose can be a perfect alternative to direct smelling. To this day, trained dogs
play major roles in the detection of narcotics and explosives, such as their use in
customs and airports, as well as military institutions. Although dogs have an excel-
lent smelling ability, they have critical limitations such as high costs for training
and maintenance. Also, the natural olfactory system is easily and rapidly adapted
to the repetitive exposure to odors; thus, the dogs cannot continuously search drugs
and explosives [ 92 ]. Hence, bioelectronic noses may replace the role of dogs within
such industries.
Bioelectronic noses can be utilized for the process monitoring using their excel-
lent sensitivity and selectivity. For instance, they can selectively detect impurities
that are contained in food and beverage products during mass production processes.
Thus, the quality control of products can be improved. Also, a sensor which detects
the smell generated from coffee roasting can accurately determine the degree of
roasting. The volatile metabolites generated from bacterial fermentation processes
can also be analyzed. Consequently, the progress of such processes can be easily
monitored in real-time using the bioelectronic noses. Bioelectronic noses can be
effectively applied to not only the examples described above, but also any cases
where the process has a resultant smell or chemical release.

14.2 Perspectives

14.2.1 Standardization of Smell

In contrast to the senses of vision and hearing, the sense of smell does not have
a method to precisely express the information of smell or flavors, even though it
plays an important role in our daily life. It is very difficult to create a database and
to standardize the information obtained from the olfactory sense, because it usually
responds to complex components consisting of a vast variety of chemical elements.
The classification and description of smell depends on quite subjective and abstrac-
tive expressions and smell cannot be precisely described or quantified using these
kinds of expressions.
In the early classification of smells, they were grouped based on the expertise
of scholars, such as a chemist and botanist, and the classification of smells through
experiments was begun in the 1900s [ 93 ]. The odor prism was proposed by Henning
(1916) suggesting verbal odor descriptions using six odor qualities, which are spice,
fragrant, resinous, ethereal, foul, and burnt [ 94 ]. From the middle of the 1930s, there
have been many trials to classify odor quality by connecting the odor perception to
its chemical structure [ 95 - 99 ], but it is still not possible to explain odor sensation