Chemical sensors

Chemical sensing technology is now employed in a wide variety of disciplines, ranging from electrochemical analysis, through biomedical measurement, to pollution monitoring and industrial control.

Chemical sensors have many applications in pollution monitoring and detection of contaminants. They are used to measure carbon monoxide levels in underground car parks and in steel plants, to detect gas build-ups in homes and coal mines, to find ammonia in frozen food and for many other applications. The pressure of legislation concerning environmental issues and public awareness of the problems makes chemical sensing of pollutants increasingly important.

Solid-state gas sensors work by measuring a physical property changed by a reaction at the surface. Solid electrolytes used in chemical sensors measure electrical conductivity changes. Catalytic sensors, such as the pellistor, measure temperature changes due to heat of reaction at the surface. Many solid-state electronic devices are used in sensors. Integrated circuits such as CMOS and thick film devices, FETs, ISFETs, MIS and MOS systems are used as the basis of sensors, as are optical fibres and surface acoustic wave devices.

Biosensors contain a part which has a biological origin, such as an enzyme or an antibody. The biological component is in contact with a suitable physical transducer which converts the biological signal into an electrical one. Applications for biosensors are in health care, the bioprocessing industry and environmental monitoring.

The increasing importance of chemical sensing technology is reflected in the Inspec Database, which provides extensive coverage of this rapidly expanding field. In Section A (Physics Abstracts), the following parts of the classification scheme contain relevant information:

 

A0670D	Sensing and detecting devices
A0710C	Micromechanical devices and systems
A4281P	Fibre optic sensors; fibre gyros
A8280F	Electrochemical analytical methods
A8280T	Chemical sensors (includes gas sensors)
A8670L	Measurement techniques and instrumentation in environmental science
A8780B	Biosensors

In Section B (Electrical & Electronics Abstracts), the relevant classification codes are:

 

B2575	Micromechanical device technology
B4125	Fibre optics
B7230	Sensing devices and transducers
B7230E	Fibre optic sensors
B7230J	Biosensors
B7230L	Chemical sensors (includes gas sensors)
B7230M	Microsensors
B7230S	Intelligent Sensors
B7320T	Chemical variables measurement
B7510	Biomedical measurement and imaging
B7720	Pollution detection and control

 

Important information can also be found in Section C (Computer & Control Abstracts):

 

C3120P	Chemical variables control
C3240	Transducers and sensing devices
C3240D	Electric transducers and sensing devices
C3240F	Nonelectric transducers and sensing devices
C3240H	Fibre optic sensors
C3240N	Intelligent sensors
C3240P	Microsensors
C3310G	Pollution control

 

The most important controlled indexing terms for the topics discussed in this article are: 

• air pollution control 
• air pollution measurement
• bioMEMS
• biosensors
• chemical analysis 
• chemical sensors 
• chemical variables measurement 
• electric sensing devices 
• electrochemical analysis 
• electrochemical sensors
• electronic noses 
• fibre-optic sensors 
• gas sensors
• intelligent sensors
• lab-on-a-chip 
• microsensors
• nonelectric sensing devices
• optical sensors 
• pollution control 
• pollution measurement 
• spectrochemical analysis 
• thick film sensors
• thin film sensors 
• water pollution control 
• water pollution measurement