The development of new technologies has brought the whole world into the era of the Internet of Things. This new era has more advancements in the area of intelligent design than the information age, and smart sensors have played an indispensable role in its development.
What is Smart Sensor Technology?
A sensor refers to a device that can sense a specified measurement parameter and convert it into a usable output signal. Sensing technology, computer technology, and communication are collectively known as the three pillars of information technology. Sensing technology is a multidisciplinary, modern science and engineering technology focused on the obtaining of information from natural sources, processing and identifying that information, and using it for planning, designing, developing, manufacturing, and testing. The degree of application and evaluation of sensors is an important indicator of a country’s informatization. Intelligent sensing technology is a comprehensive and intensive technology involving various disciplines such as micro-mechanical electronic technology, computer technology, signal processing technology, sensing technology, and artificial intelligence technology. It can realize functions that traditional sensors cannot.
Smart sensors are mainly composed of sensors, microprocessors, and related circuits. At present, smart sensors have been widely used in various fields such as aerospace, aviation, national defense, science and technology, and industrial and agricultural production.
As a tool for humans to obtain information, sensors are an important part of modern information technology. Most of the output of traditional sensors are analog signals, which do not have signal processing and networking functions. They need to be connected to specific measuring instruments to complete signal processing and transmission functions. Smart sensors are based on silicon material microfabrication and CMOS circuit integration technology. According to the manufacturing technology, smart sensors can be divided into three categories: microelectromechanical systems (MEMS), complementary metal-oxide semiconductors (CMOS), and spectroscopy. MEMS and CMOS technologies are easy to achieve low-cost mass production and can integrate sensor elements, bias, conditioning circuits, and even ultra-large-scale circuits in the same substrate or the same package, enabling the device to have multiple detection functions and intelligent data processing functions. For example, smart devices that use the Hall effect to detect magnetic fields, the See beck effect to detect temperature, the piezoresistive effect to detect stress, and the photoelectric effect to detect light.
Smart sensors can process raw data internally and can exchange data with the outside world through standard interfaces. The function of sensors can be changed through software control according to actual needs, to achieve intelligence and networking.
What are the Characteristics of Smart Sensors?
Smart sensors are characterized by high precision, high resolution, high reliability, high adaptability, and high-cost performance. The smart sensor achieves a high signal-to-noise ratio through digital processing, ensuring high precision. Through data fusion and neural network technology, they have the ability to measure and distinguish specific parameters in a multi-parameter state. Through automatic compensation, the drift of system characteristics caused by working conditions and environmental changes is eliminated, and the transmission speed is optimized so that the system works in the optimal low-power state to improve its reliability. Mathematical processing is carried out through software, so that the intelligent sensor has the functions of judgment, analysis, and processing, and the system has high adaptability. The integrated circuits and MEMSs can be mass-produced, and their cost performance is high.
What Does a Smart Sensor Do?
- Self-compensation capability: Automatic compensation for sensor nonlinearity, temperature drift, time drift, response time, etc. through software.
- Self-calibration function: After the operator inputs a zero value or a certain standard value, the self-calibration software can automatically calibrate the sensor online.
- Self-diagnosis function: After the power is turned on, the sensor can be self-tested to check whether all parts of the sensor are normal, and can diagnose faulty components.
- Numerical processing function: According to the internal program of the smart sensor, the data can be automatically processed, such as statistical processing, outlier elimination, etc.
- Two-way communication function: A closed-loop is formed between the microprocessor and the basic sensor. The microprocessor not only receives and processes the data of the sensor but also feeds back information to the sensor to adjust and control the measurement process.
- Information storage and memory function: Smart sensors can store a large amount of information data, which users can query at any time. Such information may include historical information about the device. For example, how many hours the sensor has worked, and how many times the power supply has been replaced. The content size is only limited by the storage capacity of the smart sensor itself.
With the development of science and technology, the functions of the intelligent sensors will gradually be enhanced. Artificial neural networks, artificial intelligence, and information processing technology (such as sensor information fusion technology, fuzzy theory, etc.) will give the sensor more advanced intelligence and analysis capabilities, better judgment, self-adaptation, and self-learning functions, which can help the sensor complete complex tasks such as image recognition, feature detection, and multi-dimensional detection.
The Development Trend of Sensors:
- Miniaturization: With an increasingly connected world, the demand for sensors in countless applications has exploded. Many of these applications require multiple sensors that take up very little space, show low performance degradation, and have low power requirements.
- Digitization: With so many applications in the IoT space, smart sensors need to move towards digital, not only in capturing sensory data, but also in interpreting that data for various applications.
- Sensor Fusion: With the trend of digitization, multi-sensor integration is directly connected to everything about the proliferation and expectations of IoT. The need to capture multiple types of measurements in extremely small packages is driving the development of multi-sensing elements.
Application Development of Smart Sensors:
Smart sensors represent a new generation of perception and self-awareness capabilities and are key components of future intelligent systems. Through intelligent system design at the component level, smart sensors will be used for food safety applications and biological hazard detection, safety hazard detection and alarm, local and global environmental detection, health monitoring and medical diagnosis, industrial, military, and aerospace applications, etc., and will have a profound impact on these fields.
Technical Analysis of Smart Sensors:
The development trend of smart sensors can be classified according to MEMS, CMOS, and spectroscopy. MEMS and CMOS are the two main technologies for smart sensor manufacturing.
- MEMS technology:
MEMS sensors were first used in the military field and can perform multi-sensor data fusion in the field of target tracking and automatic identification, with specific high precision and the ability to identify, track and locate targets. Flow sensors made with MEMS technology and integrated with A/D converters have been used in aerospace. Achieving intelligence requires the integration of MEMS sensor functions along with signal conditioning, control, and digital processing for bidirectional communication of data and instructions, all-digital transmission, local digital processing, self-calibration, and programming of user-defined algorithms.
- CMOS technology:
CMOS technology is the mainstream integrated circuit technology. It can not only be used to make digital integrated circuits such as microprocessors, but also sensors, data converters, and highly integrated transceivers for communication purposes. It has the advantages of integrated manufacturing and low cost. CMOS computing elements can be integrated with different sensing elements to make flow sensors, dissolved oxygen sensors, turbidity sensors, conductivity sensors, pH sensors, oxidation-reduction potential (ORP) sensors, temperature sensors, pressure sensors, touch sensors and other smart sensors used in various occasions. The market share of CMOS touch sensors and temperature sensors remains at 14% and has continued to grow in recent years. Dissolved oxygen sensors fabricated with CMOS technology and integrated with D/A converters have been used in the automotive field. Turbidity sensors with integrated transceiver functions have been used in the field of biomedicine. Digital low-light CMOS-based imagers that combine CMOS imagers and processing circuitry are becoming mainstream imagers for military applications.
Spectroscopy is an important interdisciplinary subject involving physics and chemistry. It analyzes the physical and chemical properties of matter by measuring the spectral characteristics of the interaction between light and matter. Precise multispectral measurements can be used to analyze solids, liquids, and even gaseous objects, if there is light. Spectral imaging is widely used for various object sensing and material property analysis. Hyperspectral imaging performs spectral analysis on each pixel in the image, enabling wide-range measurements.
Application Areas of Smart Sensors:
The more common smart sensors in smartphones now include distance sensors, light sensors, gravity sensors, fingerprint recognition sensors, image sensors, three-axis gyroscopes, and electronic compasses. For example, the fingerprint recognition sensor can collect fingerprint data, and then perform rapid analysis and authentication, eliminating the tedious password operation and unlocking quickly.
- Artificial Intelligence/Robots:
Sensors are the most basic hardware of artificial intelligence, like human sensory acquisition organs. Many sensors can realize perception + control, and home automation = perception + control. This level of information interaction and human-computer interaction requires more human participation. Artificial intelligence gives the human logical brain to the machine, realizes perception + thinking + execution, and finally rises to this level. The key hardware used by intelligent robots includes drives, reducers, and sensors. Intelligent sensors play an important role in collecting external information and data.
The sensing equipment in virtual reality mainly includes two parts: one part is used for human-computer interaction and is worn on the operator's body with a three-dimensional helmet display, data gloves, data clothes, etc., and the other part is used for correct perception of the real environment. Various visual, auditory, tactile, and force sensors implemented in AR/VR are required to improves the user experience.
Unmanned aerial vehicles (UAVs) are popular intelligent hardware at present. The realization of its intelligent flight control system requires the use of various intelligent sensors, including an inertial measurement unit (IMU), MEMS accelerometer, current sensors, inclination sensors, and engine intake air flow sensors. The IMU combined with GPS is the key for the drone to maintain its orientation and flight path. The development of UAV intelligence is important for direction and path control, and for air traffic management. The multi-axis magnetic sensor used by the IMU is essentially a small compass with extremely high accuracy. It transmits data to the central processor by sensing the direction, and thereby indicating the direction and speed.
- Smart wear:
Sensors play a vital role in wearable devices. The most basic function of wearable devices is to realize motion sensing through sensors.
- Smart Home:
Sensors are the basis for smart home control systems. With the development of technology, more and more sensors are used in smart home systems. The smart home field requires the use of sensors to measure, analyze and control system settings. The smart devices used in the home incorporate technologies such as position sensors, proximity sensors, liquid level sensors, flow and speed control sensing, environmental monitoring, and security sensing.
- Smart cars/autonomous driving:
The Internet of Vehicles is a major field for the development of the Internet of Things. Smart cars are the core of the Internet of Vehicles and are in rapid development. In the era of smart cars, active safety technology has become an emerging field of concern. It is essential to the improving of existing safety systems, such as rollover and stability control (ESC), which require MEMS acceleration sensors and angular velocity sensors to sense and measure body posture. Voice will become an important interaction method between people and smart cars, and MEMS microphones will usher in new development opportunities. MEMS sensors also have many applications in the automotive field, including for airbags, car engines, and more.
- Smart industry:
Smart factories use the Internet of Things technology to strengthen information management and services, master the production and sales process, improve the controllability of the production process, reduce manual intervention on the production line, collect production line data in a timely and accurate manner, and reasonably arrange production plans and production schedules, and optimize the supply chain. In the field of industrial production, sensors are widely used. Sensors are required for monitoring all aspects of industrial production, and the data is fed back to the control center so that abnormal nodes can be intervened in time to ensure normal industrial production. MEMS makes sensors miniaturized and intelligent, and MEMS sensors will have great potential in the era of the smart industry. MEMS temperature and humidity sensors can be used to detect environmental conditions, and MEMS accelerometers can be used to monitor the vibration and rotational speed of industrial equipment. High-precision MEMS accelerometers and gyroscopes can provide precise position information for the navigation and rotation of industrial robots.