A new study by researchers at Carnegie Mellon University and Disney Research has found that conductive paint can be used to create electrodes across the surface of a wall, so that it mimics a touchpad’s capabilities to track touch while an electromagnetic sensor detects electrical devices and appliances.

Called Wall++, the new system can create smart walls at a low cost of about $20 per square metre, enabling users to place light switches and other controls anywhere on a wall, or use its gesture recognition ability to control videogames.

The system can also monitor activity in the room and accordingly adjust light levels when a TV is turned on or alert the user when any household equipment turns off. The researchers were focussed on a low cost solution since walls usually involved large surfaces. A water-based paint was, therefore, selected for the application.

Using simple tools such as a paint roller and painter’s tape, the researchers applied the special coating on the wall. The painter’s tape was used to create a cross-hatched pattern on the wall and produce a grid of diamonds, which was the most effective electrode pattern.

After the application of two coats of conductive paint with a roller, the tape was removed and the electrodes connected. The wall was then finished with a top coat of standard latex paint to improve durability and conceal the electrodes.

The electrode wall operates in capacitive sensing as well as electromagnetic (EM) sensing modes. In capacitive sensing mode, the smart wall functions like any other capacitive touchpad.

In EM sensing mode, the system can identify the devices and their locations.