Zinc oxide is an important and widely used physical sunscreen. The principle of UV shielding is absorption and scattering. Zinc oxide is an N-type semiconductor, and the electrons in the valence band can accept the energy in UV light for jumping, which is the principle of its UV absorption. The function of scattering UV light is related to the particle size of the material. When the size is much smaller than the wavelength of UV light, the particles scatter UV light in all directions, thereby reducing the intensity of UV light in the direction of irradiation. In addition, if the particle size of the material is too large, unnatural whitening occurs when applied to the skin. Thus, nanoparticles offer significant advantages over the usual particles.

　　Zinc oxide is an important and widely used physical sunscreen. The principle of UV shielding is absorption and scattering. Zinc oxide is an N-type semiconductor, and the electrons in the valence band can accept the energy in UV light for jumping, which is the principle of its absorption of UV light. The function of scattering UV light is related to the particle size of the material. When the size is much smaller than the wavelength of UV light, the particles scatter UV light in all directions, thereby reducing the intensity of UV light in the direction of irradiation. In addition, if the particle size of the material is too large, unnatural whitening occurs when applied to the skin. Therefore, nanoparticles offer significant advantages over usual particles.

Zinc Oxide

Zinc oxide nanoparticles are stable compounds with a wide range of anti-bacterial, anti-inflammatory and UV resistance. It is a safe and effective ingredient in sunscreen evaluations in almost every country. However, their very small size makes them highly chemically active and can be absorbed by the body, which is potentially harmful to the human body and the environment. As a result, there is still a lot of controversy about the use of nanoscale zinc oxide, as well as controversy about the pre-use of zinc oxide for indirect methods, zinc oxide for phosphating solutions, and zinc oxide for glass.

In addition, when you wear sunscreen to wash your face or swim, or when you use lipsticks with sunscreen factors, it is likely that you will directly consume the nanoscale sunscreen contained therein for direct absorption by your body. There is still controversy about whether nanoparticles can enter the bloodstream directly through the skin. However, some argue that human skin is much thicker than lips, eyelids, inner thighs, armpits, etc. If the absorption rate of damaged skin is different, they quickly conclude that the absorption rate of such particles is almost zero.