Biomedical Engineering Reference
In-Depth Information
possibilities are being exploited with certain crops is not so much a question
of biological limitations but more of economic restrictions. Not every crop
sufficiently increases in value when costly measures are taken to influence
production processes to justify the investment. It is not a question of tech-
nological limitations. The opportunities for new technologies to add to the
already extensive toolkit of modern farmers therefore lie in improving the
economic effectiveness of their deployment.
Preharvest factors that show room for improvement can be grouped into
three categories: better monitoring of processes to be able to control the pro-
duction to a higher extent; optimizing the delivery of production factors such
as nutrients and water to the production systems; and developing more effi-
cient methods to limit the influence of quality- and quantity-reducing pests.
5.1.1 Process Monitoring
The ability to more accurately monitor processes is fundamental to improved
process control and the ability to determine when and what action to take
in which circumstances. To be able to monitor processes, it is necessary to
measure specific parameters that provide information on these processes.
With the advent of nanotechnologies, some of these parameters can be mea-
sured with more accuracy and more specificity. However, the real gain of
new technologies is that new parameters come into reach that provide much
more information. This is because nanotechnologies work at the molecular
and supramolecular levels. They allow the detection and sometimes even the
quantification of specific molecules (Lieber 2003).
The human nose (and equivalent organs in other animal species) uses a
large number of different receptor molecules (~300-350) that have the abil-
ity to bond to certain molecules that come in its vicinity. These receptors,
usually very specific proteins, are embedded in the membrane of cells in the
nose and cause an amplification process when such a docking event takes
place. This process is then detected by a neuron, which communicates the
event to the brain. When we smell a specific odor, many of the receptors
cause signals of different strengths. Our brain has learnt to interpret the
resulting pattern and to link it to, say, a ripe apple. With nanotechnology, it is
now possible to attach the same receptor molecules to a silicon surface and to
detect the docking event as a small change in the electrical properties of the
silicon. By combining many different receptors with information technology
to correlate the resulting pattern to specific odors, an electronic nose can be
developed (Gardner and Bartlett 2000).
In many biological processes, certain molecules are used for the communi-
cation between subprocesses. Well known are the hormones in humans and
animals, but also in plants hormones are excreted in specific stages of the
development process. However, organisms also produce chemical substances
that facilitate communication between individuals (e.g., to attract partners or
warn against threats) and species (e.g., to attract pollination agents or repel
