Novel smart fabric first to change color, shape with heat and electricity

British researchers have created the first smart fabric that can change shape and color in response to two different stimuli: heat and electricity. This development opens up new possibilities in various fields, including virtual reality and robotics.

Stimuli-responsive materials (SRMs) respond to the presence or change of external stimuli such as light, temperature, magnetic field or electricity. Exposure to these stimuli causes SRMs to change their shape, molecular composition, or mechanical properties.

Research so far has focused on how SRMs respond in one way, namely by changing shape or color. But for SRMs to be truly effective components of intelligent systems such as camouflage, biomimicry and sensors, they need to be able to respond to multiple stimuli. That’s where researchers at the University of Waterloo stepped in, creating the first smart fabric to change color and shape in response to multiple stimuli.

Using equipment similar to a conventional loom, the researchers weaved polyethylene terephthalate (PET) and thermochromic microcapsules (TMC) together in the weft and made of stainless steel fibers and PET in the warp of blended yarns. Stainless steel fibers give the fabric its electrical properties, while PET provides shape memory.

The interwoven structure of the smart fabric means it is as strong and supportive as normal fabric, yet flexible and soft enough to bend without unraveling.

Using a hair dryer to heat the fabric, the researchers found that it changed color uniformly from purple to blue as the temperature increased from 68°F (20°C) to 140°F (60°C). When the heat is removed, it quickly returns to its original purple color.

When the fabric is heated with electricity, it produces the same color change and changes shape, returning to its original shape when the power is turned off. Researchers can selectively activate the fabric by applying electricity to specific parts of the fabric.

In addition, the fabric is activated by a low voltage (5 V for 20 seconds), lower than previous systems. The lower voltage means the fabric could be used in smaller, portable devices, such as biomedical devices and environmental sensors, the researchers said.

“Through the ability to sense and respond to environmental stimuli such as temperature, this proves the concept that our new material can interact with the environment to monitor the ecosystem without disrupting it,” said Milad Kamkar, corresponding author of the study.

Given its cost-effectiveness — the polymers used come from recycled plastics — the researchers see great promise in their new smart fabric.

“As a wearable material, it has almost unlimited potential for artificial intelligence, robotics, and virtual reality games and experiences,” Kamkar said. “Imagine sensory warmth or physical triggers that spark deeper adventures in virtual worlds.”

The researchers plan to improve the fabric’s shape memory to make it suitable for use in robotics.

The study was published in the journal small., and the video below, produced by the University of Waterloo’s Multiscale Materials Design Lab, shows how smart materials can change color and shape in response to electricity and heat.

source: University of Waterloo