Measurement Technology - The Electronic Nose Artificial Olfaction Technology - page 13

Transducer is an electronic device that is proficient to convert one form of
energy into another. Many devices around us from the light bulb to the cell phone
to a computer screen are transducers.
A transducer mainly lists in one of the following categories:
• Electromagnetic
• Thermoelectric
• Electrochemical
• Electro acoustic
• Electromechanical
• Photoelectric
1.8.1 Transducer Characteristics
Transducers are classified according to the physical quantity they measure (e.g.,
temperature, force etc.). Beyond the obvious selection of the type of transducer
required to measure a particular physical quantity and any cost considerations, the
characteristics which are most important in determining a transducers applicability
for a given application are as follows:
• Accuracy
• Sensitivity
• Repeatability
• Range
• Precision
1.8.1.1 Accuracy
Accuracy indicates the closeness of the measured value with the actual or true
value, and is expressed in the form of the maximum error (= measured value—true
value) as a percentage of full scale reading. It is always better to choose a scale of
measurement where the input is near full-scale value. But the true value is always
difficult to get. In other words, it is a degree of conformity of the measured value
with the standard or ideal value. Also it is expressed as percentage of the sensor
range. In simple words, it represents how close a reading is to the true value.
1.8.1.2 Sensitivity
It can be defined as the ratio of the incremental output and the incremental input.
As defining the sensitivity, suppose that the input-output characteristic of the