OLED Screen Uses Liquid to Create Tactile Buttons

Researchers from the Future Interfaces Group (FIG) at Carnegie Mellon University have developed a new technology called “Flat Panel Haptics” that allows a display to protrude screen areas in various configurations. The technology can be used to add a new tactile dimension to pop-up media controls, keyboards, and virtual gamepads, creating a screen with pop-up elements that could make things like typing and playing games much less frustrating.

The technology involves embedding arrays of fluid pumps called Embedded Electroosmotic Pumps (EEOPs) on a thin actuation layer built into a touchscreen device. When an onscreen element requires a pop-up button, fluid fills a section of the EEOP layer, and the OLED panel on top bends to take that shape, creating a “button” that sticks out from the flat surface. The button recedes back into the flat display when the software dismisses it. The research team says filling each area takes about one second, and the buttons feel solid to the touch.

The main advantage of this approach is that the entire mechanical system exists in a compact and thin form factor, with device stack-ups under 5mm in thickness while still offering 5mm of displacement. The prototype is self-contained, powered only by a pair of electrical cables and control electronics, lightweight (under 40 grams for this device), and capable of enough force to withstand user interaction.

The technology is seen as a tactile equivalent to the way pixels work on displays, drawing from a common fluid reservoir and selectively modulating hydraulic pressure in and out of haptic cells. The pop-up buttons in their current form have a limited scope of shapes and sizes, but if the same principle can be applied to a layer with more and smaller pop-up buttons, it could open new doors for user interaction, including easier onscreen typing, gaming, in-car controls, and accessibility features like onscreen braille.