The concept of the Internet of Things (IoT) was proposed in 1999. Its definition is simple: connecting all objects to the Internet through information sensing devices such as radio frequency identification (RFID), infrared sensors, global positioning system, and laser scanners to exchange information and communicate, and to achieve intelligent identification, positioning, tracking, monitoring and management.
1. Definition of the Internet of Things
There are currently at least dozens of definitions of the Internet of Things (IoT), each defined by experts from different fields. We will select a few representative ones for your reference:
1. The English term "Internet of Things" can be translated as "the Internet of Things".
2. The ITU's 2005 definition of the Internet of Things (IoT): It is a sensor network that is identifiable and locatable.
3. By connecting to wireless networks (including fixed networks), objects can communicate and interact with each other, and people can communicate and interact with objects. A network that can achieve the above functions is called the Internet of Things (IoT).
4. The author favors a definition of the Internet of Things (IoT) based on a generalized network and its multi-standard, multi-system, and multi-terminal nature—or what is called the generalized Internet of Things.
2. Sensor Applications in the Internet of Things (IoT) When we talk about sensors, we might think of them on a small scale. However, in the broader concept of the Internet of Things (IoT), a ubiquitous IoT system can consider sensors as large "smart objects" depending on the reference point. These could be a robot, a machine tool, a train, or even a satellite or space probe. The IoT focuses on the practical applications of sensors, and the following is a classification based on application methods.
1. Liquid level sensor: Utilizing the principle of hydrostatics to measure liquid level, it is an important application of pressure sensors and is suitable for measuring the liquid level of various media in systems and industries such as petrochemical, metallurgy, power, pharmaceutical, water supply and drainage, and environmental protection.
2. Speed sensor: A sensor that converts changes in non-electrical quantities (such as speed and pressure) into changes in electrical quantities, suitable for speed monitoring.
3. Accelerometer: An electronic device that can measure acceleration force. It can be used in control, handle vibration and shaking, instrumentation, automobile braking and starting detection, earthquake detection, alarm systems, toys, structures, environmental monitoring, engineering vibration measurement, geological exploration, vibration testing and analysis of railways, bridges, and dams, as well as in mice, dynamic characteristics of high-rise building structures, and vibration detection for security.
4. Humidity Sensors: These are divided into resistive and capacitive types. The basic form of both is a moisture-sensitive film formed by coating a substrate with a moisture-sensitive material. When water vapor in the air is adsorbed onto the moisture-sensitive material, the impedance and dielectric constant of the element change significantly, thus creating a humidity-sensitive element suitable for humidity monitoring.
5. Gas sensor: A sensor that detects specific gases, suitable for detecting carbon monoxide, methane, coal gas, Freon (R11, R12), ethanol in exhaled breath, halitosis in the human mouth, etc.
6. Pressure sensor: It is one of the most commonly used sensors in industrial practice and is widely used in various industrial automation environments, involving many industries such as water conservancy and hydropower, railway transportation, intelligent buildings, production automation, aerospace, military industry, petrochemical, oil well, power, shipbuilding, machine tools, and pipelines.
7. Laser Sensors: Sensors that use laser technology for measurement, widely used in national defense, production, medicine, and non-electrical measurement.
8. MEMS sensors: including silicon piezoresistive pressure sensors and silicon capacitive pressure sensors, both of which are microelectromechanical sensors fabricated on silicon wafers and are widely used in defense, production, medicine, and non-electrical measurement.
9. Infrared sensor: A sensor that uses the physical properties of infrared light for measurement. It is commonly used for non-contact temperature measurement, gas composition analysis and non-destructive testing, and has applications in medicine, military, space technology and environmental engineering.
10. Ultrasonic sensor: A sensor developed using the properties of ultrasound, widely used in industry, defense, biomedicine, etc.
11. Remote sensing sensors: These are tools for measuring and recording the electromagnetic wave characteristics of objects being detected. They are used in surface material detection, remote sensing aircraft, or artificial satellites.
12. Vision sensors: Capable of capturing thousands of pixels of light from an entire image. Industrial applications include inspection, metrology, measurement, orientation, defect detection, and sorting.
Although the IoT industry supply chain includes sensor and chip suppliers, application device providers, network operators and service providers, software and application developers, and system integrators, sensors, as the base of the "pyramid," will be the largest and most fundamental link in terms of total demand. Sensors are the foundation of IoT technology, applications, and the future ubiquitous network. Sensors perceive information about objects, RFID gives them electronic codes, and the evolution from sensor networks to the IoT represents a stage in the development of information technology.
