Researchers at Cornell University have developed a dynamic braille display for electronics that changes its shape under the user’s touch. Imagine a tablet or Kindle that can display braille on command for the visually impaired using a haptic array of densely packed actuators that create popup dots using combustion. The major hurdle in designing the dynamic display is how to apply the necessary amount of force to raise each dot. Some past attempts tried implementing motors, hydraulics or pumps, and while those designs did function, they were all complex, cumbersome or expensive to implement.
“Having something that can change its shape in a way you can feel, like real objects, doesn’t exist right now. There’s this tradeoff between having small actuators and size and weight and cost. It’s so difficult,” says associate professor Rob Shepherd. “Everybody’s been trying electromechanical systems. So, we said, well, what if we don’t do that at all and we use combustion. Small volumes of gas can create powerful outputs.”
The team devised a system that uses molded silicone with embedded microfluidic traces to overcome the actuation issue. A liquid-metal electrode provides a spark that ignites a premixed methane and oxygen fuel, which travels through a series of independent channels leading to a 3mm-wide actuator. The combustion forces the silicon membranes to inflate several millimeters to create the braille dots, which can be reset by pressing them down. A magnetic latching system provides the dots with their consistent forms, which translate into words.
Since the silicon is stretchable and conformable, it can be used for other applications as well, including soft robots, wearable VR equipment with virtual touch capabilities and even surgical tools that manipulate tissue or blocked airways.