A clear nail polish has been developed that could avoid the need to awkwardly lay the pads of your fingers onto the screen for those with long fingernails.

Most modern touchscreens, such as those in smartphones and tablets, use capacitive technology that works by creating a small electric field across the screen. 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. 

But fingernails are a nonconductive material, which means they are unable to interact with a capacitive screen. 

A team from Centenary College of Louisiana has now developed a new nail polish that could make long fingernails touchscreen compatible by allowing them to carry a small electric charge. 

Previously, 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. 

Using 13 commercially available clear-coat polishes and more than 50 different additives, researcher Manasi Desai slowly worked her way through the combinations to find which ones resulted in a conductive topcoat for nails. The molecules that performed the 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 does have some toxicity. While modified taurine formula is nontoxic, it took on a slightly opaque hue. However, when combined, these additives created a formula that was able to register as a touch on a smartphone.

“Our final, clear polish could be put over any manicure or even bare nails, which could help people with calluses on their fingertips too. So it has both a cosmetic and lifestyle benefit,” Desai said. 

The polish is believed to work through the use of acid-base chemistry instead of inherently conductive metal or carbon nanotubes. The team arrived at this hypothesis because the best initial results came from ethanolamine-based formulas, which can release protons to move charge around. The researchers believe that 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. This is enough for a smartphone to register the touch. 

The team said there is still a long way to go before the polish is available on store shelves. Even the best-performing ethanolamine-taurine formula is finicky and doesn’t yet work consistently when painted on a nail. Plus, ethanolamine evaporates quickly, so the polish only works on a touchscreen for a few hours once outside of the bottle.

“We’re doing the hard work of finding things that don’t work. Eventually, if you do that long enough, you find something that does,” said research supervisor Joshua Lawrence.