MIT Engineers Invent New “Mixel” Display Technology

Most modern displays contain grids of pixels that form raster images, which are perfect for visual applications. But pixel images aren’t very useful for conveying information through non-visual means. To develop a display that has a wider range of potential applications, engineers from MIT CSAIL and the University of Calgary invented new “mixel” technology.

“Mixel” is a portmanteau of “magnetic” and “pixel,” and “pixel” is itself a portmanteau of “picture” and “element.” The engineers chose the term “mixel” because their display technology contains a matrix of magnetic elements. Like a pixel-based raster image, a grid of mixels form a picture. Special hardware sets each mixel to one of three polarity states: north, south, or demagnetized. The mixels are magnetized dots on ferrous material in sheets or other form factors, like cubes. Users can’t see the states of the magnetic pixels, but computers can with cheap sensors.

To create mixels images, the engineers modified a CNC machine with an Arduino Nano-controlled electromagnetic end effector. The machine moves to a specific coordinate on the ferrous sheet, then lowers the end effector so that it touches the material. By controlling the polarity of the electromagnet, the machine can set the state of the mixel at that location. The machine repeats that process to set the state of every mixel in the image. At any time, the machine can go back to a mixel to change its state and “redraw” the image.

The end effector also has a simple and affordable Hall effect sensor, which lets the machine detect the state of a mixel. By scanning the image one mixel at a time, the machine can develop a map of the mixel states. In a visual representation, that looks like a black and white raster image. Users can also place polarized film over the mixel image to see the mixel states and several other methods would allow computers to scan these images.

Mixel images aren’t a mere novelty — they have real practical applications. Many of these are useful because it takes a relatively large amount of processing power for a computer to scan a traditional raster image. A mixel image, on the other hand, is easy to scan using very affordable sensors and with little processing power. As an example, a QR code could be represented as a mixel image. Even the smallest QR codes can store 441 bits of data, and a couple of dollars’ worth of hardware could read such a mixel QR code.

As demonstrated in the video, mixel have other unique applications. Because they are magnetic, mixel images have physical presence. A user could move a mixel stylus across a mixel image to feel pre-programmed tactile feedback. Or a mixel “key” could interact only with the matching mixel “lock.” As with any other new technology, users will likely come up with many other useful applications for mixels.