heat effect

  microwave heating The thermal effect on organisms refers to the physiological effects on organisms caused by the heating of biological tissues or systems caused by microwave. The thermal effect is mainly due to the friction heat generated by the repeated rapid orientation rotation of polar molecules in the organism under the action of microwave high-frequency electric field; The vibration of ions in the body under the action of microwave will also convert the vibration energy into heat; Generally, molecules will also absorb microwave energy to increase thermal motion energy. If the biological tissue absorbs less microwave energy, it can use its own thermal regulation system to distribute the absorbed microwave energy (heat) to the whole body or outside the body through blood circulation. If the microwave power is very strong, and the microwave energy absorbed by the biological tissue is more than the energy emitted by the organism, the temperature of the part will rise. The rise of local tissue temperature will produce a series of physiological reactions, such as the expansion of local blood vessels, the acceleration of blood circulation through the thermal regulation system, the enhancement of tissue metabolism, the enhancement of leukocyte phagocytosis, and the promotion of the absorption and dissipation of pathological products.

Non thermal effect

The non thermal effect of microwave refers to other effects besides thermal effect, such as electric effect, magnetic effect and chemical effect. Under the action of microwave electromagnetic field, some molecules in the organism will deform and vibrate, which will affect the function of cell membrane, change the electrical status of liquid inside and outside the cell membrane, cause changes in biological effects, and then affect the central nervous system. Microwave interference with the rhythm of bioelectricity (such as ECG, EEG, EMG, nerve conduction potential, cell active membrane potential, etc.) will lead to a series of obstacles such as heart activity, brain nerve activity and endocrine activity. People do not know much about the non thermal effects of microwave. When the organism is irradiated by high power microwave, the thermal effect is the main one (it is generally believed that the power density at 10mW/cm2 will produce micro thermal effect, and the higher the frequency, the lower the intensity of thermal effect); Long term low power density (below 1 mW/cm2) microwave radiation mainly causes non thermal effects

Heating principle

Microwave is a radio wave with a frequency of 300MHz to 300GHz, and the water molecule in the heated medium material is a polar molecule. Under the action of rapidly changing high-frequency electromagnetic field (microwave), its polarity orientation will change with the change of external electric field. It causes the effect of the spin movement of water molecules. At this time, the field energy of the microwave field is converted into the heat energy in the medium, raising the temperature of the material, generating a series of physicochemical processes such as heating, and achieving the purpose of microwave heating and drying.