Smart textile technology is a revolutionary technology that uses light and heat to freely change the color of textiles, and it has the potential to be used not only in fashion but also in a variety of industries, including healthcare, architecture, and more. The commercialization of this technology could take the guesswork out of choosing the color of clothing for consumers by addressing challenges such as cost and reliability.
What color clothes to buy? We’ve all faced this question at one point or another while shopping for clothes. While it may seem like just one of life’s minor concerns to you, the fashion industry has been wrestling with this question for centuries. In today’s pluralistic society, rooted in “respect for taste,” it’s impossible to create a product line that exactly meets the needs of each individual, so the question of where to spend limited resources has always been a major concern for apparel companies.
Due to the nature of the fashion industry, color is more than just an aesthetic element; it has social and cultural connotations. For example, Chanel’s Little Black Dress in the early 20th century caused a stir when it broke away from the austere image of black and presented a new image of women. In this way, certain colors represent the spirit of a particular era. In the modern world, colors are also closely linked to consumer psychology. For example, studies have shown that when the economy is in recession, consumers tend to prefer safer colors, such as neutral shades of clothing. In this context, staying on top of color trends and reacting to them is essential to the survival of fashion brands.
However, this “fashion battle” that seemed like it would never end, unless some form of radiation leakage caused humans to no longer be able to distinguish colors, was unexpectedly solved by a defense research lab.
In June 2016, while working on a Department of Defense study as part of Google’s Jacquard project, UC Berkeley researchers accidentally discovered that the freezing point of water can be significantly altered by electric current. They realized that by passing certain currents through water molecules, they could change the molecular structure of water in a somewhat arbitrary way, and thus change its freezing point, a principle that was soon applied to fibers. After years of research, the researchers were able to “semiconduct” the fibers, which means “screen” them. Semiconductorization and screenization of textiles is a technology that literally uses textiles as semiconductors and screens to hold a certain amount of information or display some form of information on a screen, just like a smartphone. As is often the case with science and technology, the initial purpose of the research was to develop military combat clothing. A project team called the Karma Chameleon was formed to create a combat suit that could change colors like a chameleon depending on its surroundings, and from the ashes of this project, smart fabrics technology has made its way into the fashion industry and has been used by several brands.
Before explaining the principle of freely changing the color of textiles, it’s important to understand how color perception works: specific colors of light have specific wavelengths (red has a relatively long wavelength of about 700 nm, indigo has a relatively short wavelength of about 400 nm), and when an object reflects light of a specific wavelength, the light hits the retina and we perceive the color of the object. For example, if an apple appears red, it is because the surface of the object reflects only red light, which is why it appears red to our eyes, and if the surface of the apple is modified in some way to reflect only green light, we would perceive the apple as green. The surface of an object plays an important role in its color, and the technology to change the color of textiles is also based on changing the molecular structure of the fiber’s surface.
Molecular structures typically change shape when they are subjected to the right amount of energy. Advances in nanotechnology have made it possible to fabricate fibers into thin sheets of silicon called wafers, which can be used to alter the molecular structure of fibers by passing a specific current through them, and the researchers found the source of that current in everyday light and heat. To explain how light can be used to control current, it’s important to understand the switching effect. When a molecule is exposed to a certain wavelength of light (usually visible light in the 380nm-700nm wavelength range), certain parts of the molecule become disconnected and the current stops flowing, like a switch in an electronic circuit. Conversely, when the light is no longer received, the separated parts are recombined and the conductivity of the molecule increases again. In addition to conductivity, the current switching phenomenon also affects the structure of the molecule: as certain parts of the molecule are attached and detached, the molecular junction system is deformed, and the overall structure of the molecule is distorted at a certain angle. It is similar to the principle that when a long balloon is taped and blown, the taped side stretches less than the untaped side, and the overall balloon bends toward the taped side. The principle that ‘smart fibers’ using wafers with high inductivity change color when exposed to specific wavelengths of light is also based on the photoswitching effect, which is similar to the polarization phenomenon in that only certain light can be emitted by adjusting the angle arbitrarily. In theory, it is possible to change the color of the fibers somewhat arbitrarily by adjusting the wavelength of the light or adjusting the induction rate of the wafer, but it is difficult to manipulate light precisely in everyday life, so it is currently applied only to displaying text such as time, message, etc. under visible light by putting wafers with different induction rates in certain parts.
The next technology, which utilizes heat, was first developed at the EJTech lab in Budapest. The researchers discovered the thermoelectric effect, in which a voltage is generated by a temperature difference between molecules, through a “chromosonic” technology that converts sound waves into heat, and soon discovered the phenomenon of current switching by heat. Unlike the light-induced current switching phenomenon described above, where certain parts of the molecule open and close, changing the molecular structure, the heat-induced current switching phenomenon creates a potential difference in the conductor, and this potential difference changes the junction structure of the molecule, changing the molecular structure. In general, the ratio of energy converted into current is larger in the case of heat energy compared to light energy, so the color change response is much faster than that of light. The reaction is so instantaneous that the color of the textile changes just by touching it, making heat-based methods indispensable for the realization of so-called “chameleon clothes” that change color according to the environment from moment to moment. Of course, the downside is that the sophistication of color change is much lower than that of light.
As you can see, color-changing technology has endless possibilities. In particular, there’s a lot of room for applications outside of the fashion industry. For example, in the medical field, this technology could be used to develop clothes that change color depending on the patient’s condition. For example, medical clothing that changes color in response to vital signs, such as a change in body temperature or an increase in blood pressure, could help medical staff identify a patient’s condition more quickly and accurately. In architecture, smart materials that can change the color of a building’s exterior depending on the time of day or weather could be used to create a more diverse and vibrant urban landscape. These multifaceted applications show that this technology has the potential to be more than just a fashion item.
Smart textiles have come a long way from being just a pipe dream 20 years ago. However, there is still a long way to go before we can commercialize clothes that can change colors at will. Various research institutes have proposed their own solutions, but the cost and stability of making textiles from thin silicon plates, as well as the convenience of how the wearer can change colors at will, are still issues that need to be resolved. Once that’s solved, we’ll at least have one less thing to worry about: what color to buy.
