Color change textiles, otherwise known as chromic or chameleon textiles in the medical textile industry, are fabrics that change color when influenced by external stimuli. To create the transformative textile, the fabric is soaked in chromic dyes, pigments, or covered in a chromic coating. There are different kinds of chromic colorants that are each designed to react to different stimulus and act in different ways. These textiles can be used to visualize a change in environmental conditions or biological forms and can make it easier to visually recognize when a change is occurring.

The four main types of chromic textiles are:

• Photochromic Textiles: These textiles are used to measure UV radiation. When the colorless textiles are exposed to radiation, the chemical structure of the chromic colorant changes, and the electromagnetic waves appear as color. These textiles were popularized in the fashion world in the 1980s, but other applications include military camouflage and window dressings that change color in order to improve light coverage. While these textiles have not become universal due to the complex make-up of the chromic coatings, they have had more widespread integrations in other markets, mainly in eyeglasses and windows. The stimulus causes the color to develop in the textiles.

• Thermochromic Textiles: These fabrics change their molecular makeup to show a different color when there is a change in temperature. Organic thermochromic colorants are ideal for treating textiles due to the fact that organic temperatures are often close to ambient body temperatures; this will show the most accurate color change when there is a spike in temperature. Unlike photochromic textiles, it causes the color to fade from the textiles. This textile could have a universal integration in the athletic wear field, or even in the medical field as a patient monitoring tool for someone who is prone to spikes and drops in temperature.

• Electrochromic Textiles: Electrochromic materials change color based on electron concentrations. The color change occurs when a weak electric current is sent through the conductive fabric, in turn leading to a color reversal. Electrochromic textiles can be used during EEG, EKG, or EMG treatments to monitor the electrical currents. Depending on how these fabrics are treated, they can show pulses in the fabric. Ebb, a side project of Google Project Jacquard, is working towards the universal integration of textiles that rapidly change color when introduced to electrical stimuli. This sort of technology will have the ability to not only change the color of a textile, but also introduce a changing design and pattern into the garment.

• Halochromic Textiles: Halochromic textiles are materials that change based on pH levels. The colorant used on these textiles is the same used in the creation of pH sensors. A beneficial application of this textile would be as a wound dressing for a burn patient. The pH levels of the skin change drastically during the healing process of the wound, and could result in infection and further treatment without any knowledge of a pH imbalance. This textile could also have applications in the protective wear while working in a field with product that is of varying pH levels.

Each of these textile types could be beneficial in the medical industry, and could aid in monitoring of patients vitals as well as testing. A change in fabric color would expedite the process of vitals analysis and make resolving the ailment faster as well. These textiles can be used in gowns, vests, wound dressings, and more. As the medical textile industry grows, it is highly likely that more chromic textiles will appear in the hospital or and medical research settings.