What Dual-Function Pixels Are—and Why They Matter
Dual-function pixels are multifunction picture elements that can both emit light to display images and measure incoming light to record detailed optical information at the very same spot on a chip.
This is more than a clever lab trick; it is pixel architecture innovation that attacks one of the most rigid divides in modern electronics. Today, one set of pixels lights up your smartphone display, while a separate sensor full of pixels that detect light sits behind lenses to form the camera. Dual-function pixels collapse this split. Researchers affiliated with ETH Zurich have built pixels that “push out light to form images on a surface, while also taking in light and extracting detailed information about what they see”. Once this technology scales, the idea of a screen on one side and a camera on the other starts to look outdated. The phone becomes a continuous, sensing display instead of a slab with a few cut-out camera holes.
How Pixels That Detect and Emit Light at Once Work
The magic of these dual-function pixels lies in treating each pixel as a tiny sculpted landscape for light waves instead of a flat on/off lamp. The ETH Zurich team carves small wave-like patterns onto the surface of a chip with nanometre-scale precision. Incoming light is converted into a surface wave that glides across this metallic landscape, then is scattered back out as light at another point on the same pixel. By shaping the surface, they shape the light.
Because light behaves as waves that interfere—adding where peaks align and cancelling where they oppose—those carved patterns can be designed so outgoing waves form a specific image. Fourier analysis turns the desired image into an exact pattern to etch, avoiding guesswork. The same device works in reverse for sensing: the surface wave from incoming light mixes with a built-in reference wave, and the resulting interference pattern reveals not only brightness but also phase and polarization. In plain terms, each pixel becomes both a tiny projector and a precision detector of complex optical fields.
From Screens and Cameras to Camera–Displays
If a pixel can both show and sense light, the smartphone display no longer needs to be visually dead glass. It can become an active eye. Researchers describe their devices as “Fourier pixels” that can create and detect the amplitude, phase and polarization of optical fields. These bidirectional pixels make it possible to imagine camera–displays that merge both functions into a single panel instead of juggling a display stack and a separate camera module.
In the near term, the goal is a matrix of these Fourier pixels, enabling complex camera display devices. That means display sensor technology where every pixel in the grid is both a light source and a sensor, rather than sprinkling a few detectors under the glass. A lab demo already used such pixels to form a miniature logo with a letter “E” about one millimetre tall, switching its colour from green to red depending on the experiment. This is not a distant thought experiment; it is a working, if early, prototype that proves the concept.
Beyond Phones: Two-Way Screens and New Optical Tricks
Treat this as more than a smartphone story. Two-way screens that take and present pictures, holographic displays, optical communication systems and quantum information processing are all explicitly on the table with this display sensor technology. Because each pixel measures phase and polarization in addition to intensity, it can read far richer optical signals than standard camera pixels, which typically measure only brightness and colour. That opens up new modes of secure communication, precision metrology and interactive holography, where the display continuously senses and adjusts the light field in front of it.
The opinionated takeaway is clear: this is a rare case where basic physics and pixel architecture innovation may reset expectations for everyday devices. A screen that can see, at every pixel, is an entirely different platform than the passive panels we know. ETH Zurich and its collaborators have already filed patent applications and are building matrices of these Fourier pixels. The smart bet is that the first wins will appear in niche optical systems and specialised camera–displays, and once the manufacturing cost curve drops, this technology will quietly infiltrate the glass we stare at all day.
The Road Ahead for Dual-Function Pixels in Consumer Devices
If you care about future smartphones, you should care about who shapes their pixels. Here, ETH Zurich and affiliated researchers are clearly in the lead, having devised multifunction pixels that can both emit and measure light. Their work shows how a single component can handle light-emitting and light-sensing roles at once by exploiting interference over carefully sculpted metallic surfaces.
In the lab, they have already shown pixels that can steer light, analyse its intensity, oscillation phase and polarization, and react to captured images without an external computer. In the near term, building scalable matrices of these Fourier pixels into sophisticated camera–displays is the realistic next step. The broader conclusion is that display and camera hardware are on a collision course. Dual-function pixels will not stay in research papers; they are a logical way to make screens smarter, sensors denser and devices more aware of their optical environment. Once that happens, our phones, laptops and wearables will stop being mere windows on digital content and start acting as light-processing surfaces in their own right.
