Biology Reference
In-Depth Information
have been published on this topic during the last 10 years. Although it was
developed after the other techniques presented in Sections 6.2-6.5 , dielec-
trophoresis is now well established, theoretically understood, and allows for
the development of accurate, robust, and reliable biosensors.
6.7. SCALING EFFECT
Miniaturizing machines and physical systems is an ongoing effort in
human history. This effort has been increased recently as market demands
for low-cost, robust, and multifunctional products has become stron-
ger than ever. The only solution to produce them is to package many
modules (for parallelization and redundancy of operations) into the final
product and thus to miniaturize each individual component. There are
additional arguments in favor of miniaturization. Small objects require
less energy and material during fabrication. Small sensors and actuators
can be easily integrated with electronics for signal processing and com-
munication. Miniaturized systems are less invasive and need less operating
energy, opening the possibility to develop the “internet of things”. A wide
variety of environmental, industrial and security applications exist where
long-term remote (bio)-chemical analysis is either required or at least
highly desirable. 32 As a result, the design of smart miniaturized sensors,
capable of performing stable and reliable measurements without opera-
tor intervention, has become an area of increasing interest in instrument
and sensor development. A more general discussion of the application of
miniaturized systems to the detection of waterborne pathogens is given
in Chapter 10.
However, there are several physical consequences of scaling down many
physical quantities. Miniaturization is a lot more than just scaling down
spatial dimensions. A careful analysis of the scaling laws is necessary to
understand whether or not a given system can be scaled down favorably.
Depending if intensive or extensive properties are involved in the static
and/or dynamic behavior of the system, the miniaturization will have either
no effect, positive effects or negative effects on the performance. In sum-
mary, small dimensions of microsystems are crucial for some applications
but lack importance for other fields. In such a case, integration becomes
more important than miniaturization.
Focusing our analysis on scaling issues encountered in electrochemi-
cal sensors, one may wonder if electrical potential, current, and charge are
intensive or extensive properties. Potential is an intensive property. It does
 
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