First, the definition of sensors

information processing technology, as well as the progress made in the microprocessor and computer technology, high-speed development of the sensors have to work on the development of corresponding progress. Microprocessors are now measuring and control system is widely used. With the ability of these systems, information collection as a front-end module, an increasingly important role in the sensor. Sensors have become a robotics and automation systems in the key components of the system as a component of the structure, its importance is becoming increasingly apparent.

in the broadest sense, the sensor can be a physical or chemical change in the amount of electrical signals into a user-friendly device. International Electrotechnical Commission (IEC: International Electrotechnical Committee) is defined as: "The sensor is a measurement system in a pre-parts, it will enter into a variable for measuring the signal." Gopel, and so on in accordance with the statement: "sensor, including load and is connected to sensitive circuit components" and "sensor system is a combination of some information processing (analog or digital) sensor capabilities." Sensor System sensor is an integral part of its input signal is measured by the first mark.

sensor system, the principle of Figure 1-1 in the icon box, enter the sensor's signal range is very small, and mixed-signal interference and noise. In order to facilitate the subsequent process, the first signal to the whole formation of the best features of the wave, and sometimes need to signal linearization, which is handled by the amplifier, filters and other analog circuits completed. In some cases, these are part of the circuit components and sensors directly adjacent. After forming the subsequent signal into digital signal and into the microprocessor.

Germany and Russia scholars from the sensors should be part of the composition, that is perceived to be a direct measurement of the sensor signals and some of the initial processing of the signal Part of the circuit. In accordance with this understanding, the sensor also includes a signal of the former part of the circuit.

sensor system depends largely on the performance of sensors, sensor to some form of energy into another form of energy. There are two types of sensors: active and passive. Active sensors can be a form of energy directly into another, does not need external energy sources or incentives (see Figure 1-2 (a)).

active (a) and passive (b) of the sensor signal process

passive sensors can not directly form of energy conversion, but it can control the input from the other side of the input energy or incentive to
sensor will assume an object or process into a number of specific features. "Objects" could be a solid, liquid or gas, and their status can be static or a dynamic (that is, the process). Object properties can be converted to quantify the detection of a number of ways. Object properties can be physical in nature, it could be a chemical nature. In accordance with its working principle, the sensors will target properties or state parameters can be converted to electrical measurement, this electrical signal and then separated into the sensor system to measure or mark.

a variety of physical effects and working mechanism has been used for the production of different functions in the sensor. Sensors can be measured by direct contact with the object, you can not touch. Sensors for the working mechanism and the increasing effects of the type that includes process improvement.

regular feature of the sensor and human sensory organ, compared to 5 large:
light sensor - Voice-Min   visual sensor - hearing
gas sensors -   chemical smell sensors - taste
pressure-sensitive, sensitive , Fluid sensors - touch

and contemporary sensors, the human ability to feel much better, but there are also a number of sensors than the feeling superior features, such as human perception can not afford to ultraviolet or infrared radiation, electromagnetic fields do not feel, colorless and tasteless gas And so on.

sensors set up on a number of technical requirements, some to all types of sensors are applicable, there are only certain types of sensors to apply the special requirements. Sensors for the working principle and structure of the different occasions are the basic requirements are needed:

high sensitivity of anti-stability (not sensitive to noise) linear regulator easy (easy calibration)

high-precision high-reliability No delay of a long working life (durability)

repeatability in response to high-speed anti-aging anti-environmental impact (heat, vibration, acids, alkalis, air, water, dust) the ability of

selective security (sensors should be non-polluting) interchangeability of low-cost

wide range of small size, light weight, high strength and a wide operating temperature range of
  
  
Second, the classification of the sensor

can be different points of view of sensors: the principle of conversion (sensor basic physical or chemical effects); their use; their output as well as the types of materials and their production process and so on.

accordance with the principle of the sensor, the sensor can be divided into physical and chemical sensors second largest category of
sensor operating principle of the physical classification of the sensor application is the physical effects, such as the piezoelectric effect, magnetostrictive, from, polarization, thermal, optical, magnetic and electric effect. Measured tiny changes in the amount of signal will be converted to electrical signals.

chemical sensors, including those with chemical adsorption, electrochemical reactions to the phenomenon of cause and effect of the sensor, test quantity of small signal change will also be converted to electrical signals.

there should be no distinction between both sensors to the type of physical, chemical can be divided into categories. Most of the sensors is based on physical principles on the basis of the operation. Chemical sensors more technical issues, such as reliability issues, the possibility of mass production, prices, etc., to solve these problems, chemical sensor applications will be tremendous growth.

common sensor applications and the operating principle set out in Table 1.1.

in accordance with its purposes, the sensor can be classified as:
  
force and pressure-sensitive sensor   position sensor
  
  sensor surface energy sensors
  
  speed sensor thermal sensor
  
accelerometer  -ray radiation sensors
  
  vibration sensors humidity sensors
  
magnetic  -sensor gas sensors
  
  vacuum sensors, such as biological sensors.  
  
its output as a standard sensor can be divided into:
  
analog sensors -- - Will be measuring the amount of non-converted to analog electrical signal.  
  
digital sensors - will be measuring the amount of non-electrical signal into a digital output (including the direct and indirect conversion).  
  
Ying digital sensors - will be measuring the amount of signal into a frequency signal or a short cycle The output signal (including the direct or indirect conversion).  
  
sensor switch - when a measurement of the signal to reach a specific threshold, the sensor output corresponding to a set of high or low signals.
  
in the role of external factors, all materials will be made accordingly, with a characteristic response. They are those of the outside world the role of the most sensitive material, that is, those with functional properties of the materials used to produce sensors sensitive components. From the application of the material point of view sensor can be divided into the following categories:
  
(1) it using materials in accordance with the category  
  
metal     ceramic polymer mixture    
  
(2) based on the physical properties of materials at     conductor     insulator semiconductor magnetic materials    
  
(3) The crystal structure of the material by sub-  
  
  single crystal polycrystalline   amorphous materials  
  
with the new material is closely related to the development of the sensor can be summed up in three directions:  
  
(1) in material known to explore new phenomena, and the effect of reaction, and then enable them to the sensor technology in practical use.  
  
(2) to explore new materials, application of those known, and the effect of sensor technology to improve the response.  
  
(3) in the study of new materials on the basis of exploring new phenomena and new effects and reactions, and sensor technology to be specific.  

modern sensors used in the manufacturing sector depends on progress in sensor technology, new materials and sensitive component of Strength Development. Sensors developed by the underlying trend is and semiconductor materials as well as the media closely associated with the application. Table 1.2 is given in a number of sensors can be used for technology that can convert energy in the form of the material.  
  
in accordance with its manufacturing process , The sensor can be divided into:
  
  film sensor integrated sensor     ceramic thick-film sensor sensor

sensor is integrated with standard silicon-based semiconductor production technology of integrated circuits manufactured. Generally will also be used to deal with the initial part of the circuit under test signals are also integrated in the same chip.  
film sensor is the Deposition in the media through the substrate (substrate) on the corresponding sensitive material to form the film. The use of hybrid technology, the same can be manufactured in this part of the circuit substrates.  
thick-film sensor is the use of appropriate materials, pulp, coated in porcelain-on-chip made of, the substrate is usually made of Al2O3, and then heat-treated so that the thick-film forming.
ceramic sensor standard ceramic or some variant of Technology (Sol - gel, etc.) production.  
complete the preparation of the operation, the shape of the components have been carried out in the high-temperature sintering. And thick-film ceramic sensor technology between these two have many common characteristics, in some ways, that can be thick-film ceramic technology is a variant of the process.  
each technology has its own strengths and weaknesses. As the research, development and production of low capital investment, as well as the high stability of the sensor parameters and other reasons, the use of ceramic thick-film sensors and more reasonable.