I. Starting with Sensors
It is evident that sensor technology plays a crucial role in economic development and social progress. Countries worldwide attach great importance to the development of this field. It is believed that in the near future, sensor technology will experience a leap forward, reaching a new level commensurate with its significant position.
Sensors are characterized by miniaturization, digitization, intelligence, multifunctionality, systematization, and networking. They not only promote the transformation and upgrading of traditional industries but also have the potential to establish new industries, thus becoming a new economic growth point in the 21st century. Miniaturization is based on microelectromechanical systems (MEMS) technology and has been successfully applied to silicon devices to create silicon pressure sensors.
II. Electric Field Sensor
Through the above introduction, you should now have a basic understanding of sensors. In this section, we will mainly discuss electric field sensors.
An electric field sensor is a type of sensor with good resistance to electromagnetic interference and a fast response speed. It can measure transient electric fields in high-voltage power systems and can be widely used for electric field strength detection. It provides reliable means and data for meteorological support, avoids the destructive effects of strong electric fields, and is of great significance for transmitter launches. Currently available electric field sensors can only detect one-dimensional or two-dimensional electric field strength, and the detection direction is generally parallel or perpendicular to the sensor's main axis.
1. Application Principle of Electric Field Sensors
The sensors are designed to measure high-speed pulsed electromagnetic fields, particularly for measuring field strength during interference immunity testing. They consist of a differential sensor and a passive integrator. The integrator output can be directly connected to a high-speed oscilloscope. Two modes are available for measuring the electric field and the magnetic component of the field. Accurate calibration of the electric field sensor is a prerequisite for precise detection. Calibration is generally performed in a uniform electric field with known values. This typically involves applying a stable voltage to two plate electrodes spaced a certain distance apart, generating a uniform electric field between the electrodes. Currently, electric field boxes designed based on this principle are commonly used. During calibration, the sensor's sensing head is placed in the electric field box, with the sensor's sensing surface perpendicular to the direction of the electric field.
2. Applications of electric field sensors
Electric field sensors have a wide range of applications in daily life and are of great significance. The fields in which electric field sensors can be used include:
(1) Automatic switching functions can be easily embedded in home appliances. If several electrodes are embedded in the control terminals of certain appliances, these appliances will automatically start when moved and automatically shut off when returned to their original position. In addition, more electrodes can be embedded and their functions defined, allowing users to control home appliances by lightly touching these electrodes.
(2) It can easily realize applications including liquid level detection, overflow detection and humidity detection. For example, the furnace fire can be programmed and controlled so that when the liquid on the furnace is heated to boiling and overflows, the furnace fire can be automatically reduced or turned off.
(3) It can be used in touch screen input without membrane switches or expensive multilayer resistive touch panels, and without contact mechanical devices to sense the input situation. Therefore, it can eliminate the problems of wear, dust and corrosion that are often encountered by contact mechanical devices, and is especially suitable for working in harsh environments.
(4) Application in automotive safety. Elesys uses Freescale's MC33794 electric field imaging device in its SeatSentry passenger protection system to detect the size and position of passengers in order to determine whether airbags need to be deployed to avoid passenger injury due to airbag deployment.
