An undergraduate chemistry researcher has developed a nail polish formulation that will let people use their nails to tap away on touch screens. The innovation, presented this week at the American Chemical Society's annual spring meeting, addresses a problem many people have faced with increasing frustration: awkwardly laying the pads of your fingers onto the screen when wearing long nails or dealing with callused fingertips.
Manasi Desai, a student at Centenary College of Louisiana, has been working to solve the problem with her research supervisor, chemistry professor Joshua Lawrence. The challenge is fundamental to how modern smartphones work. Capacitive touchscreens create a small electric field across the screen, and when a conductive material disrupts that field, such as a finger or a droplet of water, the surface changes its capacitance, allowing the device to detect where a tap has been made. Fingernails don't conduct electricity, and there's also a condition dubbed "zombie finger," where a person's finger simply won't work with a touchscreen, usually because it's covered with thick callouses of dead skin like those of woodworkers or electric bassists.
Previous efforts to solve this problem proved impractical. Other researchers have attempted this by incorporating electrically conductive carbon nanotubes or metallic particles into nail polish, but these substances can introduce hazards to the manufacturers as they are dangerous if inhaled. Additionally, the additives result in a deep black or metallic shimmer, limiting the shade range of the polishes.
Desai's approach took a different path. To find the perfect combination of clarity and conductivity, Desai turned to trial and error, using 13 commercially available clear-coat polishes and more than 50 different additives. The molecules that performed best were forms of taurine, an organic compound commonly sold as a dietary supplement, and ethanolamine, another simple organic molecule. Ethanolamine provided the conductivity and polish compatibility they were looking for but has some toxicity, and while modified taurine formula is nontoxic, it took on a slightly opaque hue.
The work relies on chemistry rather than hardware. Unlike previous attempts, Lawrence and Desai believe their polish works through acid-base chemistry instead of inherently conductive metal or carbon nanotubes. They arrived at this hypothesis because the best initial results came from ethanolamine-based formulas, which can release protons to move charge around. When the nail polish contacts a touchscreen's electric field, it causes the protons to jump between the molecules, changing the polish's capacitance ever so slightly, but just enough for the smartphone to recognize it as a touch.
However, the formula remains experimental. Even the best-performing ethanolamine-taurine formula is finicky and doesn't yet work consistently when painted on a nail, and ethanolamine evaporates quickly, so the polish only works on a touchscreen for a few hours once outside of the bottle. Painting the polish on a fingernail doesn't leave enough additive behind to activate the screen. In future work, the duo plans to focus on improving the formula's performance in thin coats on fingernails, possibly by getting more taurine into the polish.
The motivation for the project came from a practical observation. The idea gained traction after researchers spoke with a phlebotomist who struggled with device usage during work. If refined further, the polish could help more than people concerned about aesthetics; it would address a genuine accessibility gap for anyone whose fingertips have lost natural conductivity through age, profession, or circumstance.
Desai's research has already helped her land an internship with cosmetics maker L'Oréal, as cosmetics chemistry is one of her key areas of interest. Whether the formula evolves into a consumer product depends on solving durability and consistency challenges that remain unresolved.