UV-Sensitive Indicator: ExpressInk

Our project seeks to develop a visual indicator that serves as a reminder for timely sunscreen reapplication. We propose ExpressInk - a novel, color-changing pen-like applicator for use on the skin underneath sunscreen. ExpressInk adopts an ink-like consistency by combining glycerin and rose water in a 1:4 ratio, along with photochromic pigment, inside a roller ball
bottle.

After application on the skin, ExpressInk will remain dormant as long as the sunscreen layer is actively reflecting UV rays. As the user is progressively exposed to sunlight, UV rays will penetrate the sunscreen barrier and cause the underlying photochromic pigments to change color. This not only visually confirms the sunscreen’s ineffectiveness but also reminds the user to reapply sun protection.

Another vision is for ExpressInk to become an avenue for creative expression and cultural representation through customizable designs. As a pen-like applicator, we want to encourage users to draw personal designs on their skin using colors of their choosing. These designs can range from ethnic traditions such as Inuit tattoos to contemporary urban street patterns. Each design is unique to the individual, and the beauty of light-sensitive color changes will only be revealed upon UV exposure.