Key points of sensor technology and product development

Introduction

Sensor technology is the cutting-edge technology of modern science and technology and the foundation of manufacturing automation and informatization. With the development of domestic industrial automation, informatization and national defense modernization, the annual demand for sensors continues to grow. Since the innovation of domestic sensor technology and the development of new products lag behind the advanced level of foreign countries, the development of industrial automation and informatization technology has been restricted. The basic principle of the sensor is not difficult, but the manufacturing process technology is strictly confidential. The fundamental reason for the backwardness of domestic sensor technology is the backwardness of manufacturing process technology and special process equipment, which has made the stability and reliability problems of sensors unable to be fundamentally solved for a long time, limiting the scope of use and credibility of domestic sensors. Compared with foreign sensors, especially high-tech sensors, there is a big gap between domestic sensors. The main performance indicators are 1 to 2 orders of magnitude lower than those of foreign countries, and the reliability is 2 to 3 levels lower. After years of development, although a batch of processes and products have achieved scientific and technological achievements, the stability and practicality of batch production processes have not been well solved, which has become a bottleneck for industrialization. To this end, it is necessary to accelerate the development of sensor manufacturing process technology and products. At present, the following aspects should be focused on. 1. MEMS technology and microsensors MEMS technology is a general precision three-dimensional processing technology developed on the basis of silicon planar technology. It is the core technology for studying sensors, microactuators, and micromechanical systems. The development of foreign MEMS technology has a history of 30 years. The application of MEMS technology can not only manufacture simple three-dimensional microstructures, but also three-dimensional motion structures and complex force balance structures, making modern sensor technology enter the development stage dominated by microelectronics and micromechanical integration technology from a single physical property type. The excellent performance and superior cost performance of microelectromechanical sensors will replace traditional sensors and occupy a large market share. In the production of MEMS devices, three types of production scales have been formed abroad. Large enterprises produce more than 1 million units per year; medium-sized enterprises produce 10,000 to 1 million units per year; and some research institutes produce less than 10,000 units per year. Recently, SMI, an American company, has developed a series of low-priced silicon micro pressure sensors with a linearity of 0.11% to 0.165%. They have a unique three-dimensional structure and the volume of the sensitive element is of the order of Lm, which is a few hundredths of traditional sensors. The United States has manufactured a micro inertial navigation system consisting of three gyroscopes and three accelerometers in a volume of 2cm×2cm×0.15cm. The system has a mass of 5g and a volume of only 0.1012% of that of a small inertial navigation system. In recent years, the research on MEMS processes and new sensors in China has continued to deepen and expand. The successful development and products are pressure sensors, accelerometers, micro gyroscopes, various micro actuators, micro electrodes, micro flow meters, and military micro sensors. However, only a few products such as pressure sensors have achieved mass production from chip manufacturing to assembly and testing using independently developed process technologies. At present, special attention should be paid to the application technology research of basic MEMS processes, and the development of special process equipment should be carried out to apply these processes in industrial production. Most of the process equipment currently used relies on imports, and the investment and operating costs are relatively high. For this reason, it is necessary to pay attention to the development of domestic process equipment. The electrostatic sealing equipment, silicone oil filling equipment, silicon diaphragm corrosion equipment, performance testing equipment, and silicon wafer dicing equipment developed by the Shenyang Institute of Instrumentation Science provide the equipment basis for the stable operation of some MEMS processes, and some equipment has been promoted in the industry. 2. Integration process and integrated sensor Using hybrid integration process, microsensors, microdrivers, microactuators, signal processors, control circuits, interfaces, communications and power supplies are integrated into an integrated system. The further development of integration process can make silicon microsensors, microelectronic systems and microactuators integrated on a single chip to form a closed-loop working system, which is not only an extension and extension of the concept of sensing technology, but also plays a huge role in industrial process control, aerospace, biomedicine and other fields. Microsensors and microsystems developed using MEMS technology and integration technology have unique advantages such as small size, low cost and high reliability. For example, the microsystem of pressure imagers developed abroad has a diaphragm size of 10mm×10mm, integrated 1024 micro pressure sensors, the distance between sensors is 250Lm, and the size of each pressure diaphragm is 50Lm×50Lm. Tronic has integrated more than 5,500 capacitive pressure sensitive elements on a 100mm diameter SOI substrate. The functionality and integration of physical properties is to integrate multiple sensors with different inherent characteristics on the same chip. For example, the multifunctional integrated FET biosensor integrates multiple ISFETs with different inherent component selectivity on the same chip, realizing high-accuracy multi-component analysis. NEC has developed an integrated FET sensor for detecting glucose, urea, vitamin K and white. The multifunctional silicon pressure/differential pressure sensor, which has been widely used, is a typical example of small integration. Shenyang Instrument Science Research Institute has developed a three-brick dual-island composite sensitive structure on a 4mm×4mm silicon wafer using microelectronic planar technology and micromachining technology, realizing the simultaneous measurement of three parameters: differential pressure, static pressure and temperature. 3. Intelligent technology and intelligent sensors The emergence of single-chip microcomputers has further promoted the combination of detection conversion technology and signal processing. The traditional single signal processing of detection conversion can be expanded to the simultaneous multi-signal processing of the internal state signal and environmental state signal of the object being measured. The new generation of sensors will be composed of a structural sensitive element and a surface functional device. New signal processing methods used in sensor design, such as signal correlation, multi-channel input signal comparison, digital filtering, sampling processing, etc., are now widely implemented using microcomputer digital technology, which not only diversifies the measurement functions, but also makes circuits with different measurement functions a compact whole, thereby improving the detection performance. The use of a single-chip microcomputer through software development makes it an intelligent sensor, which can automatically compensate, automatically calibrate, select the range, and self-fault to adapt to changes in the measured parameters. It is equipped with digital output, realizes two-way communication, and has strong environmental adaptability. Sensor intelligence is one of the main development directions of current sensor technology. The combination of sensor technology and intelligent technology has enabled sensors to develop from single function and single detection object to multi-function and multi-variable detection, and also enabled sensors to develop from passive signal conversion to active control of sensor characteristics and active information processing, and from isolated components to systematization and networking. The typical representative of intelligent sensors is high-performance intelligent industrial transmitters. Representative products include Yokogawa Electric's EJA series intelligent transmitters, ABB's MV2000T series multi-function differential pressure/pressure transmitters, and Rosemount's 3095MV multi-parameter mass flow transmitters. Silicon resonant sensors, composite micro-silicon solid-state sensors, and high-precision capacitive sensors are used as sensitive elements, with an accuracy of 0.1075%. They have high stability and reliability and do not require zeroing within ten years. Recently, Yokogawa Electric has successfully developed the EJX series transmitters using multivariable sensors with an accuracy of 0.1025%. In the coming period of time, intelligent sensors should develop in the following two directions: (1) Through the fusion technology of MEMS technology and IC planar technology, the microprocessor and microsensor are integrated on a silicon chip. Relying on software technology, the accuracy, stability and reliability of the sensor are greatly improved, and a new generation of fully digital intelligent sensors are designed and manufactured. (2) Using artificial intelligence methods and technologies such as hardware softening, software integration, virtual reality, and soft measurement, on the basis of sensor technology and computer technology, research and develop intelligent sensors with anthropomorphic intelligent characteristics or functions. 4. Network technology and network sensors





































Network sensors are a new generation of sensors that integrate sensors, signal processors and network interfaces with embedded microprocessors as the core. In network sensors, embedded technology and integration technology are used to reduce the size of sensors and improve anti-interference performance and reliability; the introduction of microprocessors makes network sensors a combination of hardware and software, making judgments, decisions, automatic corrections and compensation based on input signals, improving the real-time and reliability of control systems; the application of network interface technology provides great convenience for system expansion, reducing the complexity of field wiring and the number of cables.

At present, network sensors have two basic solutions: wired network sensors based on IEEE145112 standards and wireless network sensors based on IEEE145112 and Bluetooth protocols. IEEE1451 network sensors represent the development direction of the next generation of sensors. Now the network sensors designed based on IEEE145112 standards have dedicated interface modules and integrated chips such as ED1520 and PLC C-44, and the software module uses the STIM module of IEEE145112 standards. In terms of wireless networked sensors, foreign countries have launched hardware and software development platforms based on Bluetooth technology, such as Ericsson's Bluetooth development system EBDK and AD's rapid development system QSDK. Using the development system, you can easily and quickly develop radio transmission and reception modules based on the Bluetooth protocol. The development of networked sensors makes it possible for the measurement and control system to actively process information and conduct long-distance real-time online measurements. The development of networked sensors in China is in its infancy. With the need for all-round parameter detection and the development of networked technology, networked sensors will become a hot topic for future research. Conclusion At present, the development of sensor technology is at a critical stage from traditional to new sensors, which is a major change in the history of sensor development. We must seize opportunities, be innovative, and meet challenges. We must strengthen the development of new sensors with independent intellectual property rights, accelerate the transformation and industrialization of existing scientific research results, and rapidly increase the market share of domestic sensors.