I. How to Select a Sensor
1. Determine the type based on the measurement object and output conditions.
To perform a specific measurement, the first step is to consider which sensor principle to use, which requires analyzing multiple factors. For example, there are electromagnetic flow meters, vortex flow meters, and ultrasonic flow meters. We need to select the appropriate flow meter based on the specific target. In addition, we also need to consider the required output mode, such as 2-wire or 4-wire current signal, 0-20mA, 4-20mA, 0-10V voltage signal, or a specific communication protocol.
2. Selection based on sensitivity
Generally, within the linear range of a sensor, higher sensitivity is desirable. This is because only with high sensitivity can the output signal corresponding to changes in the measured quantity be relatively large, which is beneficial for signal processing. However, it should be noted that high sensor sensitivity also makes it easier for external noise unrelated to the measured quantity to enter the sensor and be amplified by the amplification system, affecting measurement accuracy. Therefore, the sensor itself should have a high signal-to-noise ratio to minimize interference signals introduced from the outside.
3. Determine the frequency response characteristics
The frequency response characteristics of a sensor determine the range of frequencies to be measured, and it must remain distortion-free within the allowable frequency range. In reality, a sensor's response always has a certain delay, and a shorter delay is desirable. A higher frequency response means a wider range of measurable signal frequencies. In dynamic measurements, the response characteristics should be considered based on the signal's characteristics (steady-state, transient, random, etc.) to avoid excessive errors.
4. Based on the stability of the sensor
The ability of a sensor to maintain its performance unchanged after a period of use is called stability. Besides the sensor's own structure, the main factor affecting the long-term stability of a sensor is its operating environment. Therefore, for a sensor to have good stability, it must have strong environmental adaptability. Before selecting a sensor, its operating environment should be investigated, and a suitable sensor should be chosen based on the specific environment, or appropriate measures should be taken to reduce the impact of the environment.
5. Sensor range and accuracy
Accuracy is a crucial performance indicator for sensors, and it's a vital factor affecting the overall measurement accuracy of a measurement system. However, sensor accuracy is limited by its measurement range; generally, a larger measurement range results in lower accuracy. But high-precision sensors may have insufficient measurement range, which makes high-precision, large-range sensors very expensive. Therefore, it's necessary to appropriately balance these factors when selecting a sensor.
II. Applications of Sensors
1. Sensors and Environmental Protection
Currently, air pollution, water pollution, and noise pollution have severely disrupted the Earth's ecological balance and the environment upon which we depend for survival, a situation that has drawn the attention of countries worldwide. To protect the environment, various environmental monitoring instruments made using sensors are playing a positive role.
2. Application of sensors in robots
In workplaces with high labor intensity or hazardous operations, robots are gradually replacing human workers. Robots are also well-suited for performing some high-speed, high-precision tasks. However, most of these robots are used for processing, assembly, and inspection, and are essentially single-function automated mechanical robots for production. These robots only utilize sensors to detect the position and angle of their arms.
3. Sensors and Home Appliances
Sensors are widely used in modern household appliances. They are found in a wide range of appliances, including electric stoves, automatic rice cookers, vacuum cleaners, air conditioners, and electric water heaters.
4. Sensors and the Internet of Things
The Internet of Things (IoT) is a network that enables all ordinary physical objects that can be independently addressed to interconnect, based on information carriers such as the Internet and traditional telecommunications networks. It has three key characteristics: the device-like nature of ordinary objects, the interconnection of autonomous terminals, and the intelligent provision of ubiquitous services.
5. Applications of sensors in medical and human medicine
With the development of medical electronics, the era of diagnosis relying solely on doctors' experience and intuition will come to an end. Now, medical sensors can be used to perform complex diagnoses such as those concerning the body's surface and internal temperature, blood pressure and intracavitary pressure, blood and respiratory flow, tumors, blood analysis, pulse waves and heart sounds, and electrocardiograms and electroencephalograms. Clearly, sensors play a crucial role in promoting the advanced development of medical technology.
6. Sensors and Remote Sensing Technology
Satellite remote sensing is a component of spaceborne remote sensing. It uses artificial Earth satellites as remote sensing platforms and primarily utilizes satellites to conduct optical and electronic observations of the Earth and lower atmosphere. In essence, it is a comprehensive technology that uses sensors on various platforms far from the ground (such as towers, balloons, airplanes, torches, artificial Earth satellites, spacecraft, and space shuttles) to detect electromagnetic wave (radiation) information on the Earth's surface. This information is then transmitted, processed, and analyzed to detect and monitor the Earth's resources and environment.
