In 1997, xenon chloride laser and light bulb began to be used in dermatology clinical, because of the single wavelength of 308nmUVB issued by it, energy concentration, and the wavelength is shorter than 311nm, stronger biological effect, can shorten the treatment course, so it is widely used in the treatment of localized vitiligo and psoriasis. Commonly referred to as 308nm excimer laser UV phototherapy and 308nm excimer UV phototherapy.

Since 2001, as light emitting diode (LED) began to be widely used in lighting field, ultraviolet solid-state LED light sources were also developed and produced. However, due to low luminous efficiency, it can not be used in clinical treatment for more than ten years. In recent years, with the market size of the deep ultraviolet field has attracted the attention of more and more enterprises, ultraviolet (UV)LED related technologies have made rapid progress, and at present, some specific bands of UVA, UVB, UVC and other LED light sources can be realized for commercial application.

In 2018, the first SQ308LED UV phototherapy instrument developed and produced by SIGMA Technology Co., LTD. (SIGMA) obtained the marketing authorization of the State Medical Products Administration, and was recognized by various medical institutions in the subsequent clinical application.

In 2019, SIGMA developed and produced the first SQ308LED UV phototherapy instrument for home use by patients under the guidance of doctors.

SQLED chips are used in the LED light sources of the above two products. SQ(Sigma Quality) represents the ultimate quality that meets the requirements of Sigma. SQ LED is the third generation of gallium aluminum nitride LED, which has pure spectrum, stable strength, good heat dissipation and long life. SQ LED requirements used for each LED chip can represent the perfect combination of international advanced UV semiconductor technology and process, in the output wavelength, output power intensity and stability after strict detection and screening, is synonymous with high quality LED.