Biomedical Engineering Reference
In-Depth Information
CHAPTER FOUR
SENSOR TECHNOLOGIES
Sensors perform a significant part of an electronic device by providing the interface
to the surrounding range of interest. The sensors may be of wireless or data-bus
connection, and can consist of a huge number of miniaturised micro-technology-
based solutions or state-of-the-art design that intend to deliver data in effective,
consistent or intelligent applications. Most applications of today still use single
sensor (or mostly a very few) in applications intended to measure quantifiable
values in a restricted partially defined range of the environment. This structure
may instead result in a physical property were the sensor will contribute to the
specific part of the object and change its quantitative parameter(s) caused by the
measurement system. For example, measuring the temperature in a sealed cup of
water will probably affect the measurement if a sensor is entered into the water,
due to the difference in temperatures between the sensor unit and the measured
object, i.e., the water.
Artificial sensor structures, or simply sensors, perform a vital function in mea-
surement and control applications of today, namely to provide an interface to the
real world. However, the glimpse from a sensor measurement may often, only
reflect the local spot of its range that it is focussed on. The sensor performance
usually exhibits an artificial reflection, e.g., often in non-real-time with adherent
discrepancies that makes the sensor data just artificial mimicking units of the real
world, and maybe with an annoying time lag. Nevertheless, it is of importance to
have enough knowledge of the sensor behaviours before considering the measure-
ment specification - what do we want to achieve?
This chapter is intended to be an initial insight to sensor technologies before
moving on to the artificial perceptual sensor and its applications. There will be
an overview of the classical sensor operational principles that extensively offer an
introduction to the importance of artificial sensors as an information source.
A sensing unit can, in general terms, be defined as a;
“device that is receptive to external stimuli and transforms it to communicable data ”.
This definition is very broad and covers everything from human senses, for
example the human eye, to gas sensors used in a fire detection system and sensors
used to track the speed of a car.
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