A standard color LCD or OLED display only uses three colors to create the illusion of a full-color spectrum. A research team at Meiji University in Japan have developed an equivalent for taste: a lickable screen that uses five electrolyte gels to create the illusion of a full range of flavors. The team published a paper chronicling the production of the technology known as the Norimaki Synthesizer.

Inspired by optical technology, the Norimaki Synthesizer uses gels made of agar that contain electrolytes corresponding to the five primary tastes. Building on past studies, the team chose glycine for sweet, sodium chloride for salty, glutamic sodium for umami (savory), citric acid for acidic, and magnesium chloride for bitter.

When the inactive screen is placed on the tongue, the user tastes all of the gels at once. Once activated, the system sends a mild electric current through the gels. A remote control can adjust the intensity of each taste separately, by changing the level of electrical charge within each gel.

Increasing and decreasing the current results in the ability to mix an array of flavors. Just as an optical display uses red, blue, and green flashing lights to trick the brain into seeing lavender, chartreuse, or periwinkle, the Norimaki Synthesizer can convince the brain that the tongue is enjoying sushi, gummy candy, and a wide range of other foods.

The system’s potential to provide virtually unlimited, user-controlled flavors speaks to its potential use in VR platforms. When it comes to health, simulating sweet or salty food could provide dietary variety for diabetics or high blood pressure patients. It could also boost weight loss outcomes by helping users stick to a weight management plan. Or perhaps, multiple users could enjoy the same meal from any location: an option that might enhance mental wellness for those in extreme social isolation such as during the COVID-19 lockdown.