When Nikola Tesla predicted we would have portable phones that could display videos, photos, and more, his musings seemed like a distant dream. Almost 100 years later, smartphones are like an extra accessory for many of us.
Digital manufacturing engineers are currently working to expand the display capabilities of other everyday objects. One possibility they’re exploring is reprogrammable surfaces — objects whose appearance we can digitally change — to aid users present critical information like health statistics, as well as recent designs for things like a wall, a mug, or a shoe .
Researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL), the University of California, Berkeley, and Aarhus University have taken an intriguing step forward by fabricating “PortaChrome”, a portable lighting system and design tool that can change the color and texture of various objects. Equipped with ultraviolet (UV) and red, green and blue (RGB) LEDs, the device can be attached to everyday items such as T-shirts and headphones. Once a user creates a design and sends it to a PortaChrome device via Bluetooth, the surface can be programmed with multi-color displays of health, entertainment and fashion design data.
In order for an item to be reprogrammed, the object must be coated with photochromic dye, an undetectable ink that can be turned into different colors using vivid patterns. Once coated, individuals can create and transfer patterns to the item using the team’s graphic design software, or operate the team’s API to directly interact with the device and embed data-driven designs. When attached to a surface, PortaChrome UV lights saturate the dye while RGB LEDs desaturate it, activating the colors and ensuring that each pixel has the tone consistent with the intended design.
Zhu and her colleagues’ integrated lighting system changes the colors of objects in less than four minutes on average, eight times faster than their earlier work, “Photo-Chromeleon.” This speed boost is due to switching to a lithe source that is in contact with the object to transmit UV and RGB rays. The Photo-Chromeleon project used a projector to activate the color-changing properties of a photochromic dye, where the lithe on the object’s surface has a reduced intensity.
“PortaChrome provides a more convenient way to reprogram your environment,” says Yunyi Zhu ’20, MEng ’21, an MIT doctoral candidate in electrical engineering and computer science, CSAIL associate and lead author of the book article about work. “Compared to our previous projector-based system, PortaChrome is a more portable light source that can be placed directly on the photochromic surface. This allows color change to occur without user intervention and helps avoid environmental pollution from UV radiation. As a result, users can, for example, wear a heart rate graph on their shirt after training.”
Giving everyday objects a makeover
In demonstrations, PortaChrome displayed health data on a variety of surfaces. The user hiked with PortaChrome sewn into the backpack, touching it directly to the back of a shirt coated with photochromic dye. The altitude and heart rate sensors transmitted data to the lighting device, which was then converted into a graph using a reprogramming script developed by the researchers. As a result of this process, a visualization of the user’s health condition appeared on the back of the user’s shirt. In a similar demonstration, MIT researchers showed a heart gradually converging on the back of a tablet to show a user’s progress toward a fitness goal.
PortaChrome has also shown a knack for adapting wearable devices. For example, researchers redesigned some white headphones with side blue lines and horizontal yellow and purple stripes. The headphones were coated with a photochromic dye, and then the team attached the PortaChrome device to the inside of the headphone housing. Finally, the researchers managed to reprogram their patterns onto the object, making it resemble a watercolor painting. Using this process, researchers recolored the wrist splint to match different clothes.
Ultimately, the track could be used to digitize consumers’ belongings. Imagine putting on a coat that can change the entire design of your shirt, or using a car cover to give your vehicle a recent look.
Main ingredients of PortaChrome
On the hardware side, PortaChrome is a combination of four main components. Their portable device consists of a textile base acting as a kind of skeleton, a textile layer with UV lamps soldered and another with RGB glued on it, and a silicone diffusion layer on top. Resembling a translucent honeycomb, a layer of silicone covers interwoven UV and RGB LEDs and directs them towards individual pixels to properly illuminate the design on the surface.
This device can be flexibly wrapped around objects of various shapes. For tables and other flat surfaces, you can place PortaChrome on top like a placemat. For a curved object like a thermos, you can wrap the lithe source like a coffee cup sleeve to make sure it reprograms the entire surface.
A portable, pliant lighting system is created using tools available in the manufacturer’s space (such as laser cutters, for example), and the same method can be replicated using pliant PCB materials and other mass production systems.
While it can also quickly transform our surroundings into animated displays, Zhu and her colleagues believe that increasing the speed further could benefit it. They would like to operate smaller LEDs, which would likely result in a surface that could be reprogrammed in seconds with a higher resolution design thanks to increased lithe intensity.
“The surfaces of our everyday objects are encoded with colors and visual textures, providing key information and shaping the way we interact with them,” says Georgia Tech postdoc Tingyu Cheng, who was not involved in the research. “PortaChrome takes a step forward by providing programmable surfaces by integrating pliant lithe sources (UV and RGB LEDs) and photochromic pigments with everyday objects, pixelating the environment with animated colors and patterns. The possibilities presented by PortaChrome have the potential to revolutionize the way we interact with our surroundings, especially in areas such as personalized fashion and adaptive user interfaces. The technology enables real-time personalization that integrates seamlessly into everyday life, offering a glimpse into the future of “ubiquitous displays.”
Zhu is joined in the article by nine CSAIL staff members: MIT graduate student and MIT Media Lab partner Cedric Honnet; former visiting researchers Yixiao Kang, Angelina J. Zheng, and Grace Tang; MIT undergraduate student Luca Musk; University of Michigan Assistant Professor Junyi Zhu SM ’19, PhD ’24; recent postdoc and assistant professor at Aarhus University Michael Wessely; and senior author Stefanie Mueller, TIBCO associate professor of career development in MIT’s departments of electrical engineering, computer science, and mechanical engineering and leader of the HCI engineering group at CSAIL.
This work was supported by the MIT-GIST Joint Research Program and was presented in October at the ACM Symposium on User Interface Software and Technology.