The walls of your house keep the roof up, give your family some privacy, and maybe provide a place to hang some art. But researchers at Disney and Carnegie Mellon University have come up with a way for walls to do more. A cheap paint treatment turns them into giant sensors, creating new ways to interact with a smart home by just walking around in it.
Unlike other methods of detecting the movement of people or objects in a room, Wall++ doesn’t need obtrusive cameras, bright projectors, or even garish tracking markers covering every last surface. It instead involves a unique paint treatment that even novice home decorators could apply.
A grid of diamonds is first created using conductive paint, and is then covered by another grid of very thin wires connecting them all together like nodes. A final layer of standard latex house paint hides everything underneath, and the researchers estimate the treatment costs about $20 per square meter, but could be even cheaper when mass produced.
The diamond and wire grid essentially create a very crude version of the capacitive touchscreens found on smartphones, tablets, smartwatches, and countless other pieces of tech. When your finger, which conducts electricity, makes contact with the screen, it changes the electrical charge on that specific area of the display, and the underlying hardware can use that change to pinpoint your finger’s position and movements.
The same thing happens with the grid of conductive diamonds painted on the Wall++ experiment. The approach is considerably cruder, which means it’s far less accurate than your smartphone’s touchscreen, but by monitoring the electrical charge across the diamonds as a human gets close to it, the wall, and accompanying custom software, can figure out the location of a person nearby with surprising accuracy.
Imagine just tapping anywhere on a wall to turn a light off in a room, or sliding your hand up it to turn up the thermostat. The functionality is not limited to human interactions, though. The wall treatment also works as a giant electromagnetic sensor, and is able to detect and differentiate appliances and electronics by the unique electromagnetic noise they produce.
And that’s just what a single Wall++ unit can do. Most rooms have at least three or four walls, and the possibilities get even more interesting when a space is completely surrounded with sensors. The same techniques that allow a single Wall++ to detect where a person is touching it, also allow multiple walls to detect electronics and appliances in a 3D space.
Did you remember to turn the TV off in the living room before you went to bed? Even if it’s a 40-year-old dumb CRT that’s not designed to play nice with a modern smarthome, the Wall++ could let you know if it’s still powered on or not. The days of misplacing your muted smartphone could also be a thing of the past. A single text message or call would generate electromagnetic noise allowing the walls of your home to tell you exactly where you forget it. The walls finally have ears, and maybe that’s not as scary as it seems.