Chapter 1
Definition of sensors
Sensor (transducer/sensor) is a measurement device that converts measured to a certain amount of physical material with which it has a certain degree of accuracy to determine its counterpart, enabling it to complete its detection mission; its input is a measured quantity, which may be physical, which may be chemical, biomass, etc.; and its output is a physical mass, which is easy to transmit, convert, process, display, etc., and can be gas, light, electricity, etc., but mainly electricity. The mode of input-output conversion (relationship) of the sensor is known and the accuracy of the conversion is required to meet the application requirements of the monitoring and control system。
Sensor applications (areas) vary and are called differently, e. G., in process control referred to as a transformer, or standardized sensors referred to as transmitters, receivers or probes in radio detection。
In contrast, the sensitivity is described below. Sensitivity is a device or device that converts a measured non-power to a sensor that can use non-power. X is measured as non-power, z is used as a sensor, y is exported as a sensor, and the sensitivity transfer function is
Z = zirconium(x)
Sensor transfer function is
Y = z
Sensitive sensor composite function:
Y=(z)=[x)]=f(x)
2. Composition of sensors
The composition of the sensors is shown in figure 1-1. Of these: the direct perception of the sensitive element is measured and the output of the physical amount measured in a defined relationship; the conversion element uses the output signal of the sensitive element as its input signal and converts it into a circuit parameter; and the connection of the above circuit to the conversion circuit can be converted into an electrical output。
Figure 1-1 composition of sensors
Material-type sensors made of semiconductor materials, which basically combine sensitive and conversion elements, can be directly converted from measurements to electrical output, such as voltage sensors, pvs, heat-sensitive electrical resistance, etc。
3. Classification of sensors
The variety of sensors, their different rationales and the variety of subjects to be tested are such that there are many classifications and no uniform classification has been established. People are usually classified from different angles, highlighting one side. Below are a few common classifications。
1) the classification is based on the principles, patterns and effects of the physical, chemical and biological disciplines, which can be classified into three main groups: structural, physical and composite。
Structured sensors: consisting of sensors using laws of physics, etc., whose performance is not relevant to the material. The geometric dimensions (e. G. Thickness, angle, location) of such sensors are subject to changes in measured effects and to the availability of telecommunications numbers proportional to the measured non-electricity。
Material-type sensors: sensors consisting of one or more objective properties of the substance whose performance varies significantly from material to material. The physical, chemical or biological characteristics of the material forming such a sensor are directly sensitive to the measured non-power and may be converted to telecommunications numbers。
Composite sensor: means a sensor that combines an intermediate conversion link with a material sensitive element. The intermediate is used because, in large quantities of non-electricity measured, only a few (e. G., mutation, light, magnetic, heat, moisture and certain gases) can directly take advantage of the material properties of certain sensitive materials for conversion to telecommunications, so in order to increase the range of measurements of non-electricity, it is necessary to convert non-electricity that cannot be directly converted to one of the few physical volumes mentioned above, and then to convert it to telecommunications using the corresponding material-sensitive metaware。
The advantages of classifying by working logic are that there is a clearer analysis of the working principles of the sensors, with fewer categories, and that this allows for general analysis and research in theory and design。
2) classification by energy relationship. The energy control sensor, also known as the passive sensor, is not an energy-replacement device per se, and is measured as non-power only to control or regulate the energy in the sensor, so it must have a supplementary energy source, such sensors being classified as electrical resistance, capacitating and sensory, and commonly measured on bridges, etc. Energy conversion sensors are also known as energy exchangers or active sensors, which typically convert non-electric energy into electrical energy and are usually equipped with electro-voltage measurements and magnification circuits, such as voltage sensors, thermoelectric sensors, pressure resistance sensors, etc。
3) categorised by input volume, sensors can be divided into commonly used sensors such as organic, photo, electrical and chemical sensors such as place transfer, velocity, acceleration, force, temperature and flow sensors。
4) classification by the nature of the output signal can be divided into analogue sensors and digital sensors。
Direction of development of sensor technology
1) the development of new sensitive/sensitization materials. After physical volumes such as detection power, heat, light, magnetic, gas, etc. Change the performance of semiconductor materials to produce sensitive elements such as sensitivity, heat sensitivity, light sensitivity, magnetic sensitivity and sensitivity, greater emphasis is placed on basic research to find sensitive elements and sensor elements with new principles and effects。
2) development of new sensors and formation of new test systems
The development of micro-sensors using mems technology, such as ccd sensors for micro-reconnaissance aircraft, for piping wall creeping robots, visual sensors, etc。
Development of biomimicators。
Development of sensors for marine detection。
Develop sensor for component analysis。
Development of a weak signal detection sensor。
3) studying a new generation of intelligent sensors and test systems such as electronic sphygmomanometers, intelligent water, electricity, gas, heat meters, etc. They are characterized by the organic integration of sensors with microcomputers, which form intelligent sensors whose system functions are achieved to the maximum extent by software。
4) the integration of sensors has been rapidly developed with the further development of solid functional materials and the development of integrated technologies. Integration, i. E. The integration of more individual sensor elements of the same type into one-dimensional or two-dimensional array sensors on the same chip; or the integration of sensors with circuits such as regulation, compensation, etc。
5) studies of multifunctional and multiparametric sensors, such as sensors that simultaneously detect pressure, temperature and fluid levels, have been progressively marketed。
