A sunscreen that not only protects your skin but also provides a refreshing effect: a promising innovation could turn this idea into reality.
The secret of this innovation lies in radiative cooling, a technique that leverages the reflective or emissive properties of a surface to dissipate heat. Previously used in the design of cooling fabrics and coatings for buildings, this principle now finds a novel application in the cosmetic field.
The team led by Rufan Zhang modified the properties of titanium dioxide (TiO₂) nanoparticles, commonly found in mineral sunscreens. By carefully adjusting their size, the researchers managed to create a sunscreen that reflects not only UV rays but also solar heat.
The innovative formula combines six ingredients: TiO₂ nanoparticles, water, ethanol, moisturizer, pigments, and polydimethylsiloxane. The latter, a silicone polymer frequently used in cosmetics, gives the sunscreen its light and even texture. This combination achieves a sun protection factor (SPF) of 50 while ensuring water resistance.
During tests conducted under hot and humid conditions, the product demonstrated a significant reduction in skin temperature—up to 10.8 °F (6 °C) compared to bare skin and 5.4 °F (3 °C) compared to conventional sunscreens. Trials on human and animal subjects also confirm the safety of this formulation.
Beyond its effectiveness, this sunscreen stands out for its affordability. Estimated at $0.92 for 10 grams, its price is competitive with products already available on the market. This cost-performance balance paves the way for large-scale commercialization.
This technology could inspire the development of similar solutions in other sectors, including textiles and coatings, thereby enhancing resilience to increasingly hot summers.
What is radiative cooling?
Radiative cooling is a physical phenomenon by which an object loses heat by emitting infrared waves.
This process relies on a surface's ability to reflect or radiate thermal energy independently of the ambient temperature. It is particularly effective under clear and dry conditions.
Used in science and technology, radiative cooling has inspired innovations ranging from architectural coatings to cooling fabrics. In this particular case, it enhances cosmetic products.
How does titanium dioxide contribute to radiative cooling?
Titanium dioxide (TiO₂) is a material commonly employed to reflect UV light and solar heat. Its optical properties make it a key player in radiative cooling.
TiO₂ nanoparticles, depending on their size, can amplify this effect by reflecting not just visible light but also infrared radiation. This helps lower the temperature of exposed surfaces.
In formulations like sunscreen, these modified nanoparticles serve a dual purpose: protecting against UV rays while dissipating solar heat, thus providing added comfort.
Article author: Cédric DEPOND