Spray-On Touchpad

Most of us are accustomed to touch-sensitive surfaces being built into flat, rigid structures such as a tablet or smartphone screen. But engineers at Carnegie Mellon have come up with a conductive paint that can turn nearly any surface into a touchpad easily and inexpensively, enabling objects and surfaces that were previously static to become responsive and interactive.

Called Electrick, the new material is compatible with a variety of manufacturing methods, including spray/brush coating, casting/molding and vacuum-forming. It can be applied to many types of surfaces — large or small, flat or irregular. It utilizes a principle known as electric field tomography that can be used in conjunction with electrically conductive wires to replace physical buttons.

For example, the team turned an entire wall into a touch sensitive light switch by coating it with the paint and attaching it via copper wires to a computer. Tapping the wall turned the lights on and off, while swiping a finger across it increased or decreased the brightness. In another demonstration, they created a touch-sensitive steering wheel, which could be used in an autonomous vehicle to determine when a human was driving.

Electrick touchpads are 99 percent accurate at detecting touch; however, they can be off by as much as a centimeter in determining the precise location of that touch. Although this limitation will restrict the technology’s usefulness for certain applications, it still holds promise for use in many large-scale installations where this level of precision is adequate.