The Application and Characteristics of Fiber Bragg Grating Humidity Sensors

Fiber optic temperature sensor, Intelligent monitoring system, Distributed fiber optic manufacturer in China

In the field of measurement, temperature and humidity monitoring must have a significant proportion in various different places. With the progress of science and technology and the demand for industrialization, higher requirements have been put forward for temperature and humidity sensors in terms of environmental adaptability, measurement accuracy, and measurement range. The current situation is that electrical temperature and humidity sensors are still dominant in the market due to their advantages such as low cost, fast response speed, and easy signal processing. However, there are some issues with electrical sensors that cannot be ignored, such as poor interchangeability and insufficient long-term stability, and they are not suitable for applications in fields such as electrical, electrical, and petrochemical industries where there are flammable and explosive harsh environments.

With the rapid development of science and technology, the demand for precise measurement of physical parameters in nature is becoming increasingly urgent. During this process, fiber optic sensing technology has also achieved comprehensive development and widespread application, including the technology of using fiber Bragg gratings for sensing and measurement. As is well known, fiber optic gratings can accurately measure temperature, stress, strain, displacement, acceleration, etc., while measuring environmental humidity is a newly developed field that faces many urgent scientific and engineering challenges. Traditional humidity sensors use functional materials to absorb environmental moisture and change their electrical parameters such as resistance and capacitance for humidity detection, while fiber Bragg gratings measure humidity by converting changes in water molecule content in the environment into changes in optical parameters of light waves, which has inherent advantages in high-precision measurement.

In the fields of aerospace, electrical and electrical engineering, military and meteorological, pharmaceutical and tobacco, it is necessary to monitor environmental humidity. Therefore, improving the performance of humidity monitoring instruments and ensuring that they meet the needs of different detection environments is of great significance. The traditional types of humidity sensors include hair type, wet and dry bulb type, as well as capacitive, resistive and other humidity sensors. These types of humidity sensors are susceptible to interference from harsh environments such as electromagnetic, oil and gas, have poor stability, and limited application range. Humidity sensors are widely used in many fields, such as industrial control, pharmaceutical production, agricultural planting, meteorological detection, and food storage. It is of great significance to achieve rapid and accurate measurement of humidity in these fields. Mature electrical humidity sensor products in the market, such as resistive humidity sensors and capacitive humidity sensors, have advantages such as high measurement accuracy and fast response speed. However, their long-term stability and interchangeability are poor, and they may fail and even cause safety accidents in certain special applications (such as strong electromagnetic environments and oil and gas detection environments). Therefore, a passive detection humidity sensor is needed in some flammable and explosive situations.

Electrical sensors have been widely used in various testing and measurement equipment, but they have many limitations, such as transmission loss, susceptibility to interference, and inability to be applied in harsh environments. In recent years, with the development of optoelectronics, optical signals have gradually replaced electrical signals in sensors due to their anti-interference and low loss performance.

Fiber optic sensors are passive sensors that are not easily affected by electromagnetic signals. They are inherently safe (i.e. flame retardant, explosion-proof) and can adapt to flammable and explosive environments such as electrical, electrical, chemical, and pharmaceutical industries. Moreover, fiber optic sensors have a small volume, light weight, and are more easily placed in narrow areas for long-distance network monitoring.

The most commonly used fiber optic humidity sensor is the fiber optic grating humidity sensor. The fiber optic grating type temperature and humidity sensor is a new type of temperature and humidity sensor that has developed with the development of fiber optic communication technology. Compared with traditional electrical temperature and humidity sensors, it has advantages such as anti electromagnetic interference, good electrical insulation, and large dynamic range. In addition, the sensing part is lightweight, small in size, diverse in structure and geometric shape, and easy to reuse for networking to achieve real-time, online, and distributed sensing. Due to the insensitivity of fiber optic gratings to humidity, they need to be combined with humidity sensitive materials to form humidity sensitive components.