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Published on November 22nd, 2016 | By: April Gocha, PhD

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Can materials science change the color of your clothes on a whim?

Published on November 22nd, 2016 | By: April Gocha, PhD

[Image above] Thermochromic paint-coated conductive fibers allow researchers to change the color of thread with a little power supply. Credit: University of California Berkeley

 

 

A few weeks ago, a popular Australian online fashion retailer called Showpo posted a video on its Facebook page that seemed to debut a magically color-changing dress.

 

In the video, the dress appears to be wirelessly connected to an iPad, on which the touch of a finger on a digital color wheel instantly changes the color of the dress.

 

Watch for yourself.

Credit: Showpo Channel; YouTube

 

 

But you know you can’t believe everything on the internet.

 

Although the company afterwards admitted that the dress isn’t “yet” real, Showpo nonetheless says it’s confident it can create such a magical color-changing dress.

 

And the company might be right.

 

One way to change the color of thread is to make it conductive, using an electrical current to catalyze a color change.

 

Making conductive threads and weaving them into pieces of clothing is not nothing new. In fact, Google has a whole project dedicated to innovating and mass-producing interactive textiles called Project Jacquard.

 

But, as Wired reports, although conductive fabric isn’t anything new, producing conductive fabrics at scale is. And that’s what Project Jacquard is all about. It wants to create interactive textiles that can be made in the same factories that are already producing textiles—no new technology, machinery, or equipment needed.

 

The idea behind the technology itself is simple—interweave a small amount of conductive threads in with other normal textile fibers, allowing an ordinary piece of cloth to become connected and interactive. Project Jacquard has a goal of manufacturing interactive textiles that can transform clothing, furniture and more into interactive objects that can recognize touch and gestures.

 

The idea is similar to that of a capacitive touchscreen—the technology can recognize the conductivity of your skin and translate simple movements or gestures into commands.

 

And if you can create conductive threads, it’s not that much more of a stretch to create conductive threads that change color.

 

Researchers at UC Berkeley did it just earlier this year. Their project, called Ebb, is one under the umbrella of Google’s Project Jacquard.

 

Ebb uses conductive threads coated with thermochromic pigments, which change color as electricity flows through the threads and heats them up (ever so slightly), according to a Berkeley news release.

 

The authors presented the work earlier this year at the 2016 CHI Conference on Human Factors in Computing Systems.

 

According to the conference proceedings, Ebb’s conductive thread is made of cotton wound with copper and insulated with a thin coating of enamel.

 

Current heats up the thread and “changes the pigments in the fabric paint from an opaque to transparent state and results in a visual effect of the thread fading to its uncoated white color,” the authors write in the proceedings.

 

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Credit: University of California Berkeley

 

In addition to changing the color of your shirt on a whim, part of the idea behind Ebb is to create e-ink that could essentially integrate electronics and wearables right into your clothing—so that your watch would be a part of your shirt, for example, or your cuff could alert you to a missed call.

 

Watch this short demonstration of a few of the ideas Ebb has fabricated using its thermochromic conductive threads (no camera tricks here!).

 

Credit: Ebb CHI 2016; YouTube

 

Just like Project Jacquard’s idea of integrating new technology into existing textile factories, the idea is to eliminate extra unnecessary elements—instead integrating technology into our existing clothing and environment. However, Ebb’s technology so far changes colors slowly, so fast responsive displays aren’t yet feasible.

 

And because Ebb’s thread is coated with thermochromic paint, that also means that the thread changes color with any heat—not just heat from a supplied electrical current. So sitting in a patch of sunlight on a warm day or getting a little sweaty after riding your bike could also change the color of your shirt, too.

 

Another downside of Ebb’s fibers is that the threads have a limited lifecycle—the researchers report that the thermochromic paint becomes permanently transparent after repeated heating cycles. The threads held up for more than 500 short heating cycles in the researchers’ tests, but that lifetime depends on how much power is supplied through the thread and how long it’s heated.

 

But thermochromic paint isn’t the only option for color-changing threads.

 

Take an example from nature: chameleons have color-changing skin that contains photonic crystals that reflect different wavelengths of light as they change orientation, changing the perceived color of the lizards.

 

“The animal changes its colors via the active tuning of a lattice of nanocrystals,” physicist Jérémie Teyssier and biologist Suzanne Saenko say in a Huffington Post story. “When the chameleon is calm, the latter are organized into a dense network and reflect the blue wavelengths. In contrast, when excited, it loosens its lattice of nanocrystals, which allows the reflection of other colors, such as yellows or reds.”

 

It’s not hard to imagine materials scientists could devise a similar crystal orientation-dependent color-changing textile. In fact, researchers at Ecole Polytechnique de Montréal and Concordia University in Canada already developed photonic bandgap fibers that can change appearance depending on how they’re illuminated by light.

 

In that unpublished paper’s abstract, the authors write: “We demonstrate how photonic crystal fibers enable a variety of color and structural patterns on the textile, and how dynamic imagery can be created by balancing the ambient and emitted radiation.”  

 

Although the color changes with such threads likely wouldn’t be quite as simple as the tap of a touchscreen, the idea of a color-changing dress may be less magical than completely feasible.

 

So the short answer is yes, materials science can create color-changing clothes—but we’re still waiting for a dress as dynamic as Showpo’s.

 


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