What is the temperature measurement used for microwave digestion equipment

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

What is microwave digestion technology

Microwave digestion technology uses microwave heating to heat the sample. Due to the strong penetration and high frequency of microwave, the temperature of the heated sample rises rapidly and uniformly from the inside. The purpose of the digestion test is to destroy and dissolve the surface layer and internal structure of the sample, and react with acid to enable the sample to dissolve quickly. Compared with traditional digestion and heating methods, microwave digestion technology is widely used due to its advantages of high efficiency, low reagent usage, cleanliness, energy conservation, and easy monitoring.

How to measure temperature with a microwave digestion device

At present, the key technology of microwave digestion equipment lies in how to online detect the real-time temperature of the sample during the digestion process. Traditional temperature sensors, such as thermocouples, platinum resistors, etc., are made of metal materials. These temperature measuring probes, due to the interference of strong electromagnetic fields in the microwave field, will generate induced currents, causing their own temperature to rise, resulting in significant measurement indication errors or the inability to perform stable temperature measurements. In recent years, fiber optic temperature sensors with new temperature measurement technologies have developed at a very fast pace. The emergence of fiber optic temperature sensors has made significant breakthroughs in resistance to electromagnetic interference, insulation, reliability and stability of temperature sensors. This provides a new concept and technical means for the real-time temperature measurement of microwave digestion instruments.

Due to the importance of temperature parameters in microwave heat treatment, temperature detection has been achieved in many fields where microwave fields exist, such as various microwave ovens, microwave reactors, and microwave therapeutic devices. These temperature detection technologies include conventional ones such as thermocouple temperature sensors, as well as thermosensitive transistors and integrated circuit temperature sensors. However, in the microwave field, due to the presence of strong electromagnetic fields, temperature measuring probes and wires made of metal materials generate induced currents under high-frequency electromagnetic fields. Due to the skin effect and eddy current effect, their own temperature rises, causing serious interference in temperature measurement, resulting in significant errors in temperature readings or inability to perform stable temperature measurements.

What is fiber optic sensing technology

Fiber optic sensing technology developed rapidly in the 1970s with the development of fiber optic communication technology. The light wave, as the carrier of the measured signal, and the optical fiber as the propagation medium of the light wave, have a series of unique advantages that are difficult to compare with other carriers and media: the light wave does not generate electromagnetic interference, is not afraid of electromagnetic interference, is easy to receive by various optical detection devices, can conveniently perform photoelectric or electro-optical conversion, and is easy to match with highly developed modern electronic devices and computers; Fiber optic has a wide operating frequency and a large dynamic range, making it a low loss transmission line. The fiber optic itself is not charged, small in size and lightweight, easy to bend, resistant to electromagnetic interference, and has good radiation resistance. It is particularly suitable for use in harsh environments such as flammable, explosive, strictly limited space, and strong electromagnetic interference. Some developed countries abroad have achieved rich results in the application research of fiber optic sensing technology, and many fiber optic sensor systems have been put into practice, becoming commodities that replace traditional sensors.

How to use fiber optic temperature sensors in microwave digestion equipment

Fiber optic temperature sensing is an important branch of fiber optic sensing. All temperature related optical phenomena or characteristics can essentially be used for temperature measurement, and based on this, the existing optical technologies for temperature measurement are quite abundant. The commercialized fiber optic temperature sensors account for nearly 20% of all fiber optic sensing products. Due to the inherent anti electromagnetic interference and other characteristics of fiber optic temperature sensing technology, it has been widely used by many researchers for temperature sensing in microwave fields.

Induction heaters and furnaces commonly used in the microwave industry use high-power alternating electromagnetic fields to quickly heat conductive objects. In addition, in other applications of industrial microwave, such as microwave food processing and drying, microwave glass melting, papermaking, textile, wood drying, microwave sintering of ceramics and dental appliances, microwave disinfection, microwave insecticidal, traditional resistance temperature sensors are no longer suitable.

There is an urgent need to find a temperature measurement method that is resistant to electromagnetic interference, radiation, and can be used in harsh environments such as flammable, explosive, microwave, and radio frequency in special temperature measurement applications. With the rapid development of fiber optic manufacturing technology, fiber optic sensing technology, signal analysis and processing technology, fiber optic temperature measurement methods have gradually evolved into a new type of temperature measurement technology. Generally, fiber optic temperature sensors are mainly composed of three major components: fiber optic, light source, and photodetector. Compared with other traditional temperature sensors, it has many advantages: insulation, anti electromagnetic interference, and anti radiation; Small size, light weight, bendable, and easy to install; Sensitivity and measurement accuracy, high cost, and stable chemical properties.