A sensor is a detection device that can feel the information being measured and can transform the sensed information into electrical signals or other required forms of information output according to a certain rule, so as to satisfy the transmission, processing, storage, and display of information, Recording and control requirements.
The characteristics of sensors include miniaturization, digitization, intelligence, multi-function, systemization, and networking. It is the first link to realize automatic detection and automatic control.
1. The working principle of the sensor
The sensor is generally composed of four parts: sensitive element, conversion element, conversion circuit, and auxiliary power supply.
Among them, the sensitive element directly receives the measurement and is used to output the physical quantity signal related to the measurement. The sensitive element mainly includes heat sensitivity, light sensitivity, humidity sensitivity, gas sensitivity, force sensitivity, sound sensitivity, magnetic sensitivity, color sensitivity, taste sensitivity, and radioactivity sensitivity.
Ten major categories; conversion components are used to convert the physical quantity signals output by sensitive components into electrical signals; conversion circuits are used to amplify and modulate the output electrical signals of the conversion components; auxiliary power supplies are used to provide the system (mainly sensitive components and Conversion element) provides energy.
2. Sensor application
Application of sensors in mobile phones: gravity sensors, which are almost perfect in games; acceleration sensors, such as the shaking function of mobile phones, which sense the acceleration of mobile phones; light sensors, such as the automatic dimming function of mobile phones; distance sensors. For example, when the phone leaves the ear, the screen becomes brighter, and the screen becomes black when the phone is close to the ear. There are countless sensors in mobile phones, and many functions are realized by sensors. Health sensors can be connected to www.
In addition to bracelets and watches, sensors also have a wide range of applications in daily life, such as: automatic doors, which control their on-off state by sensing the infrared microwave of the human body; smoke alarms, through the sensing of smoke concentration To achieve the purpose of alarm; electronic scales measure the weight of people or other objects through mechanical sensing; water level alarms, temperature alarms, humidity alarms, etc. also use sensors to complete their functions.
3. What’s the sensor trends?
A. Development of new sensors-sensor trends 1
The new sensor should generally include: ①Select new principles; ②Add sensor blanks; ③Bionic sensors, etc. They are connected to each other. The operating mechanism of the sensor is based on various effects and laws, which inspires everyone to further explore sensitive functional materials with new effects, and develop new physical sensor materials with new principles based on this.
This is the development of high-function, multi-function, low The main way of cost and miniaturization of sensors.
Structural sensors developed earlier and are now becoming more sophisticated. Structural sensors are usually said to be messy in structure, large in size, and high in price. Physical property sensors are roughly the opposite, and have many attractive advantages.
Countries all over the world have invested a lot of manpower and material resources to strengthen research on physical sensors, making it a noteworthy development intention. Among them, a low-active threshold sensor developed using various effects of quantum mechanics to detect weak signals is one of the new intentions.
B. Integration, multi-function and intelligence-sensor trends 2
Sensor integration includes two definitions. One is the side-by-side arrangement of multiple elements with the same function. The single sensor elements of the same type are placed on the same plane with integrated technology. The linear sensors and CCD images are arranged in one dimension. The sensor falls into this situation. Another definition of integration is multi-function integration, which integrates sensors with amplification, calculation, and temperature compensation to form a single device.
With the development of integrated technology, various types of hybrid integrated and monolithic integrated pressure sensors have emerged one after another, and some have become products. Integrated pressure sensors include piezoresistive, capacitive, and other types, among which piezoresistive integrated sensors are developed quickly and widely used.
The multifunctionalization of sensors is also one of its development directions. A typical example of so-called multi-function, a single-chip silicon multi-dimensional force sensor developed by a sensor research and development base of a university in the United States can measure 3 linear velocities, 3 centrifugal accelerations (angular velocities) and 3 angular accelerations together.
The main element is a monolithic silicon structure composed of 4 cantilever beams accurately planned and installed on a substrate, and 9 piezoresistive sensitive elements accurately arranged on each cantilever beam. Multi-function can not only reduce production costs and reduce volume, but also can effectively advance the stability and reliability of the sensor.
Integrating multiple sensing elements with different functions together can not only measure multiple parameters together, but also summarize and evaluate the measurement results of these parameters, which can reflect the overall status of the system under test. It can also be seen from the above that integration has brought many new opportunities to solid-state sensors, and at the same time it is also the basis for multi-function.
The combination of sensors and microprocessors makes them not only have inspection functions, but also have artificial intelligence such as information processing, logic discrimination, self-diagnosis, and “thoughts”, which is called the intelligentization of sensors.
With the help of semiconductor integration technology, some sensors are manufactured on the same chip with signal pre-processing circuits, input and output interfaces, microprocessors, etc., which become large-scale integrated smart sensors. It can be said that smart sensors are products that combine sensor technology and large-scale integrated circuit technology. Its realization will depend on the advancement and development of sensor technology and semiconductor integration technology.
This type of sensor has many advantages, such as multi-function, high function, small size, suitable for mass production and convenient use. It can be said with certainty that it is one of the main directions of the sensor.
C. New material development-sensor trends 3
Sensor materials are the main foundation of sensor technology and the main support for the promotion of sensor technology. With the advancement of material science, sensor technology has become more sophisticated and its varieties have been increasing. In addition to the semiconductor materials and ceramic materials used in the early days, the development of optical fibers and superconducting materials has provided a material foundation for the development of sensors.
For example, according to the fact that many semiconductor materials based on silicon are easy to be miniaturized, integrated, multifunctional, and intelligent, and semiconductor photothermal detectors have the characteristics of high activity, high precision, and non-touch, the development of infrared sensors, lasers Modern sensors such as sensors and optical fiber sensors; the development of high-sensitivity materials, ceramic materials, and organic materials is rapid. Different formulations and mixed materials can be selected.
Based on the fine chemical composition, high-precision molding and sintering are used to obtain the right A sensitive material with identification function for a certain type of gas or several types of gas is used to make a new gas sensor.
In addition, high-molecular organic sensitive materials are new types of sensitive materials that have been highly valued in recent years. They can be made into heat-sensitive, photosensitive, gas-sensitive, humidity-sensitive, force-sensitive, ion-sensitive, and biological-sensitive sensors. The continuous development of sensor technology has also promoted the development of newer materials, such as nanomaterials.
The US NRC company has developed a nano ZrO2 gas sensor that controls the exhaust emissions of motor vehicles, which has an excellent effect on purifying the environment and has a wide range of prospects for use. Because the sensor made of nanomaterials has a huge interface, can supply a lot of gas channels, and has a small on-resistance, which is conducive to the development of miniaturization of the sensor. With the continuous advancement of science and technology, more new materials will be born. .
D. Selection of new technology-sensor trends 4
In the new sensor, it is inseparable from the selection of new technology. The significance of the new technology is very wide, and here mainly refers to the micro-processing technology that is particularly close to the development of new sensor contacts.
This technology, also known as micro-machining technology, has been developed with integrated circuit technology in recent years. It is the technology used for microelectronic processing such as ion beam, electron beam, molecular beam, laser beam and chemical etching. It has been increasing. It is used in the field of sensors, such as sputtering, evaporation, plasma etching, chemical gas deposition (CVD), epitaxy, diffusion, corrosion, lithography, etc. So far, there have been many domestic and foreign sensors using the above technologies Report.
E. Smart materials-sensor trends 5
Smart materials refer to planning and manipulating the physical, chemical, mechanical, electrical and other parameters of materials. Artificial materials that have characteristics of materials for research and development may be better than those of biological materials. Some people think that materials with the following functions can be called smart materials: they can be adaptive to the environment; they are self-diagnostic; they are self-correcting; they are self-enhancing (or time-based).
The most prominent feature of biological materials is the time-base function, so the characteristics of this sensor are differential, and it is somewhat sensitive to variation. Conversely, if you stay in a certain environment for a long time and get used to it, your activity will decrease. Generally speaking, it can adapt to the environment to regulate its activity. In addition to biological materials, the most obvious smart materials are shape memory alloys, shape memory ceramics and shape memory polymers. The exploration of smart materials has just begun, and I believe that there will be great development in the near future.
With the advancement of the Internet of Things technology, new requirements have been put forward for sensor technology. Products are moving to MEMS process technology, wireless data transmission network technology, new materials, nanometers, thin films (including SOI), ceramic technology, optical fiber technology; laser technology, composite sensors Technology, the development of multi-disciplinary integration technology.