Massachusetts Institute of Technology (MIT), Uppsala University, and KTH Royal Institute of Technology researchers have developed a novel type of fiber that can be made into clothing that senses its level of stretching or compression. It then offers immediate tactile feedback as pressure, lateral stretch, or vibration. According to a study published in Science Daily, the fabric could be spun into garments that assist singers or athletes in controlling breathing, or help patients convalescing from illness or surgery recover their breathing patterns.

The team designed multilayered fibers with a center fluid channel, activated by a fluidic system. This controls the fibers’ geometry through pressurization and release of compressed air or water into the channel, creating an “artificial muscle” effect. Stretchable sensors embedded in the fabric detect and measure the fibers’ degree of stretching. The composite fibers are thin and flexible enough for use in standard commercial machines.
The “OmniFibers” were presented during October’s Association for Computing Machinery’s User Interface Software and Technology online conference.

The fiber’s very narrow size and inexpensive material facilitate structuring it into many fabric forms. It’s compatible with skin since the outer layer is composed of a material similar to polyester. A fast response time and strength and variety of forces it can exert allow a rapid feedback system for training or remote communications using haptics.

Ozgun Kilic Afsar, a visiting doctoral student and research affiliate at MIT, said most existing artificial muscle fibers are hampered by the fact that they’re either thermally activated—which can cause overheating when contacting skin—or have low power efficient or difficult training processes. She said they also have sluggish response or recovery times, limiting the potential for rapid feedback.

To first test the material, the team constructed an undergarment singers can wear to monitor and play back respiratory muscle movement, later giving kinesthetic feedback via the garment to train on optimal posture and breathing patterns needed for the vocal performance.

“Singing is particularly close to home, as my mom is an opera singer. She’s a soprano,” Afsar told MIT News. She also worked with classically trained opera singer Kelsey Cotton during the design and fabrication stages.

“I really wanted to capture this expertise in a tangible form,” Afsar said. “We eventually were able to achieve both the sensing and the modes of actuation that we wanted in the textile to record and replay the complex movements we could capture from an expert singer’s physiology and transpose it to a nonsinger, a novice learner’s body. So, we are not just capturing this knowledge from an expert, but we are able to haptically transfer that to someone who is just learning.”

The researchers also posited OmniFibers could be used to help athletes learn breathing control for given situations, based on monitoring professional athletes as they perform activities and stimulating muscle groups in action. These garments could be used to help patients recover healthy breathing patterns after major surgery, a respiratory disease like COVID-19, or perhaps as a novel and alternative sleep apnea treatment.

Hiroshi Ishii, the Jerome B. Wiesner Professor of Media Arts and Sciences at MIT, said training for muscle movements beyond breathing might also be a potential application area.

“Many of our artists studied amazing calligraphy, but I want to feel the dynamics of the stroke of the brushes,” he said. This could be engineered with a sleeve and glove made of OmniFibers.

“The fiber-level engineering and fabric-level design are nicely integrated in this study,” said Lining Yao, an assistant professor of human-computer interaction at Carnegie Mellon University. This work demonstrates “different machine knitting techniques, including inlay and active spacer fabric, advanced the state-of-the-art regarding ways of embedding actuating fibers into textiles,” she said. “Integrating strain sensing and feedbacks is essential when we talk about wearable interactions with actuating fabrics.”

The team intends to continue work on miniaturizing the whole system and develop a manufacturing method able to make longer filaments. In the coming months, the team plans to conduct experiments in using the system to transfer skills from an expert to novice singer, and later to explore other movement practices like choreographers and dancers.