Touch sensing has tended be most common on small, flat surfaces such as smartphones and table screens but this research has shown that it is possible to extend that capability to walls, furniture, steering wheels and toys. The technology has been named ‘Electrick’.
The technique involves applying electrically conductive coatings or materials to objects or surfaces using conductive materials. Researchers were able to attach a series of electrodes to conductive materials and then use a technique called electric field tomography to sense the position of a finger touch.
"For the first time, we've been able to take a can of spray paint and put a touch screen on almost anything," said Chris Harrison, assistant professor in the Human-Computer Interaction Institute (HCII) and head of the Future Interfaces Group.
At present large touch surfaces tend to be both expensive and irregularly shaped and many have relied on computer vision, which can be disrupted if a camera's view of a surface is blocked.
Electrick works by applying conductive paints, bulk plastics or carbon-loaded films, among other materials to conductive touch services.
According to HCII Ph.D. student Yang Zhang the Electrick technique is, "compatible with many common manufacturing methods."
Electrick relies on the shunting effect - when a finger touches the touchpad, it shunts a bit of electric current to ground - to provide the touchscreen experience. By attaching multiple electrodes to the periphery of an object or conductive coating, the team were able to show that they could localise where and when such shunting occurs. They did this by using electric field tomography, sequentially running small amounts of current through the electrodes in pairs and noting any voltage differences.
While the team conceded that accuracy was an issue Electrick is able to detect the location of a finger touch to an accuracy of one centimeter, which is sufficient for using the touch surface as a button, slider or other control, Zhang said.
Researchers used Electrick to add touch sensing to surfaces as large as a 4-by-8-foot sheet of drywall, as well as objects as varied as a steering wheel, the surface of a guitar and a Jell-O mold of a brain.
Zhang said the Electrick surfaces proved durable. Adding a protective coating atop the conductive paints and sheeting also is possible.
