UV LED in skin care field

In recent years, ultraviolet (UV) light emitting diode (LED) related technologies have advanced by leaps and bounds, and commercial applications of LED light sources such as UVA, UVB, and UVC in certain wavelength bands have been realized. Although the current medical LED power, especially the light extraction efficiency, is not ideal, it has significant advantages in environmental protection and light source life. It is not uncommon to report on its application in the health field at home and abroad, especially in the treatment of skin diseases. With the continuous improvement of various technical designs, the power of UV LED is gradually increased, and the single irradiation time for light diagnosis and treatment is greatly shortened, which effectively improves the efficiency of clinical work and saves doctors and patients time.

LED lighting principle and advantages

LED is a solid-state semiconductor device that can directly convert electrical energy into ultraviolet light. Each LED is composed of a PN junction, which has the characteristic of unidirectional conduction. When the forward voltage is applied to the light-emitting diode, the holes injected from the P area to the N area and the electrons injected from the N area to the P area recombine with the electrons in the N area and the holes in the P area respectively near the PN junction. Fluorescence that produces spontaneous emission (Figure 1, 2). LEDs made of different materials emit light of different wavelengths. For example, UVB LEDs made of aluminum gallium nitride (AlGaN), a new-generation semiconductor material, can emit ultraviolet light with a peak wavelength of 308nm and other narrow UVB bands.

UV LED, a new type of ultraviolet light source, is characterized by high photoelectric conversion efficiency and good band monochromaticity. Before UV LED light sources entered clinical use, UV light sources were mainly fluorescent mercury lamps, xenon chloride excimer light/lasers, metal halide lamps, etc. Fluorescent tubes contain mercury. As people's awareness of environmental protection increases and the issuance of international environmental protection contracts such as the Minamata Convention, its use will gradually be restricted. The light source of xenon chloride excimer light/laser is a consumable, which is expensive, and the treatment fee is correspondingly high. It has certain limitations in clinical use. The metal halide lamp has a wide spectrum and requires a special filter to emit light in the wavelength band required for treatment. UV LEDs make up for the shortcomings of the above-mentioned light sources, and have a long service life and stable output. The light source does not need to be replaced during the life of the equipment. The cost of use in hospitals is lower, and it has a good prospect for popularization and application.

Application of UVALED equipment in dermatology

Basic research shows that under the same irradiation dose, UVA1 LED and UVA1 fluorescent tube have similar effects on the apoptosis and necrosis ratio of Jurkat cells [1]. In the mouse experiment of Shunko A. Inada et al. [2], the body and surface temperature were measured when UVA1 LED and fluorescent lamp were irradiated. The body temperature of mice in the UVA1 fluorescent lamp group reached 40.5℃ when irradiated with 30 mW/cm2 intensity for 18 minutes. The experiment was terminated due to non-response; at the end of the experiment, the body surface temperature of the LED group increased by 3°C-4°C; the body surface temperature of the fluorescent lamp group increased by 8°C -10°C, indicating that UVA1 LED light source had a more burning sensation than fluorescent light low.

A high-intensity, 365nm UVA LED light skin tester with a wavelength of 365nm was used to compare with a monochromator light tester (monochromator light testing) of this wavelength. The results showed that its photosensitivity test effect is better than the latter, and it has low cost, compactness and convenience. Many advantages.

UVA1 phototherapy instrument is commonly used to treat atopic dermatitis, scleroderma, granuloma fungoides and other diseases, and can also be used for the treatment of psoriasis. For patients with large skin lesions, the laser products currently on the market have a limited output area, while the output intensity of fluorescent tubes is low. The equipment with metal halide lamps as the light source is huge due to heat dissipation requirements, and the treatment room also needs special Modification, a new type of equipment with LED as the light source can effectively avoid the limitations of the above equipment.