Student develops nail polish that turns fingernails into touchscreen stylus

A college student has developed a prototype nail polish that allows fingernails to work like a touchscreen stylus, offering a possible solution for people with long nails, calloused fingertips or reduced skin conductivity.

The project was led by Manasi Desai, a chemistry student at Centenary College of Louisiana, in collaboration with research supervisor Joshua Lawrence, an associate professor of chemistry. Their aim was to create a clear, non-toxic polish that could let a fingernail interact with a touchscreen in the same way as a fingertip.

Desai said the final formulation can be applied over an existing manicure or directly to bare nails. The researchers said the product could also help people with calluses, dry skin or other conditions that make touch input difficult on phones and tablets.

Touchscreens work through capacitance, where conductive materials such as human skin disrupt a small electric field and register a touch. Because fingernails are non-conductive, they usually do not activate screens, creating a problem for people who rely on their nails instead of their fingertips.

Researchers said the problem has sometimes been described as “zombie finger,” a term used when touchscreens fail to respond because of reduced conductivity. The team set out to find a safer and more practical alternative to earlier experiments that used carbon nanotubes or metallic particles.

Those previous materials raised safety concerns and also limited the appearance and color options of nail polish. Desai instead tested 13 commercially available clear nail polishes and more than 50 additives before developing a formula that remained clear, non-toxic and conductive.

The final version uses taurine, an amino acid, along with ethanolamine, an organic molecule. According to the researchers, these ingredients allow the polish to register touch input on a smartphone through acid-base chemistry.

Lawrence said the interaction between acidic and basic groups enables proton exchange at the polish’s surface, helping it mimic the ion movement that allows human skin to activate a touchscreen.

The research was presented on March 23 at the annual meeting of the American Chemical Society. The product is still in development and is not yet ready for commercial use.

Researchers said current versions lose effectiveness after a period ranging from a few hours to a few days, while the goal is to extend durability to days or weeks. They also said the least-toxic version still leaves a gritty and speckled finish, which the team is trying to improve.

The researchers have filed a provisional patent and said work is continuing to refine the formula and improve both performance and usability.