A new type of fiber developed by researchers at MIT and Sweden can be made into a garment that senses how stretched or compressed it is, then provides immediate tactile feedback in the form of pressure, side stretch, or vibration. According to the team, such fabrics could be used in clothes that help singers or athletes better control their breathing, or that help patients recovering from illness or surgery regain their breathing.
Multilayer fibers contain a fluid channel in the center, which can be activated by a fluidic system. This system controls the geometry of the fibers by pressurizing and releasing a fluid, such as compressed air or water, into the channel, allowing the fiber to act like an artificial muscle. The fibers also contain stretchable sensors that can sense and measure the degree of stretching of the fibers. The resulting composite fibers are thin and flexible enough to be sewn, woven or knitted using standard commercial machines.
Fibers, dubbed OmniFibers, are featured this week at the Association for Computing Machinery’s UI Software and User Interface Technologies online conference, in an article by Ozgun Kilic Afsar, visiting doctoral student and research affiliate at MIT; Hiroshi Ishii, Jerome B. Wiesner Professor of Media Arts and Sciences; and eight more from the MIT Media Lab, Uppsala University and the KTH Royal Institute of Technology in Sweden.
The new fiber architecture has a number of key features. Its extremely narrow size and the use of an inexpensive material make it easy to structure fibers into a variety of fabric shapes. It is also compatible with human skin, as its outer layer is based on a material similar to common polyester. And, its rapid response time and the strength and variety of forces it can transmit enables a rapid feedback system for training or distance communications using haptics (based on the sense of touch).
Afsar says that the faults of most existing man-made muscle fibers are that they are either thermally activated, which can cause overheating when used in contact with human skin, or that they have low effectiveness. energetic or strenuous training processes. These systems often have slow response and recovery times, which limits their immediate use in applications that require rapid feedback, she says.
As the first test application of the material, the team created a type of undergarment that singers can wear to monitor and replicate the movement of the respiratory muscles, to later provide kinesthetic feedback through the same garment to encourage optimal posture and breathing patterns for the desired person. vocal performances. âSinging is particularly close to where I live, because my mother is an opera singer. She’s a soprano, âshe says. In the process of designing and manufacturing this garment, Afsar worked closely with a classically trained opera singer, Kelsey Cotton.
âI really wanted to capture this expertise in tangible form,â says Afsar. The researchers asked the singer to perform while wearing the garment made from their robotic fibers and recorded motion data from strain sensors woven into the garment. Then, they translated the sensor data into the corresponding tactile feedback. âWe were finally able to get both the sensing and actuation modes we wanted in the textile, record and replay the complex movements we could pick up from the physiology of an expert singer and transpose them to the body of the singer. ‘a non-singer, a novice learner. So we not only capture this knowledge from an expert, but we are able to transfer it haptically to someone who is just learning, âshe says.
While this initial test is in the context of vocal pedagogy, the same approach could be used to help athletes learn to better control their breathing in a given situation, based on tracking athletes accomplished in performing various activities and stimulation of muscle groups. which are in action, says Afsar. Ultimately, the hope is that such clothing can also be used to help patients regain healthy breathing after major surgery or respiratory illness such as Covid-19, or even as an alternative treatment for sleep apnea. (which Afsar suffered as a child, she says).
The physiology of respiration is actually quite complex, explains Afsar, who is doing this work as part of his doctoral thesis at the KTH Royal Institute of Technology. âWe don’t really know what muscles we are using and what the physiology of breathing is,â she says. So the clothes they designed have separate modules to monitor different muscle groups as the wearer inhales and exhales, and can replay the individual movements to stimulate the activation of each muscle group.
Ishii says he can foresee a variety of applications for this technology. âEveryone has to breathe. Breathing has a major impact on productivity, confidence and performance, âhe says. âBreathing is important for singing, but it can also help when recovering from surgery or depression. For example, breathing is so important for meditation.
The system could also be useful for training other types of muscle movements besides breathing, he says. For example, âA lot of our artists have studied amazing calligraphy, but I want to feel the dynamics of the brushstroke,â which could be accomplished with a sleeve and glove made of this closed-loop feedback material. And Olympic athletes could hone their skills by wearing an item of clothing that mimics the movements of a top athlete, whether a weightlifter or a skier, he suggests.
The flexible fiber composite, which looks like a strand of wire, has five layers: the innermost fluid channel, a silicone-based elastomeric tube to contain the working fluid, a stretchable flexible sensor that senses strain as a change in electrical resistance, a braided polymeric stretchable outer mesh that controls the outer dimensions of the fiber, and a non-stretchable filament that provides mechanical stress on the overall stretchability.
âFiber-level engineering and fabric-level design are well integrated into this study,â says Lining Yao, assistant professor of human-machine interaction at Carnegie Mellon University, who was not associated with this research. This work demonstrates that “various machine knitting techniques, including inlaid fabric and active spacer fabric, have advanced the state of the art regarding ways to integrate actuator fibers into textiles. “, she says. âThe integration of strain sensing and feedbacks is essential when we talk about wearable interactions with actuation tissues. ”
Afsar plans to continue working to make the entire system, including its control electronics and compressed air supply, even more miniaturized to keep it as unobtrusive as possible, and to expand the manufacturing system to be able to produce. longer filaments. Over the next few months, she plans to begin experiments using the system to transfer skills from an expert to a novice singer, and later explore different types of movement practices, including those of choreographers and performers. dancers.
The research was supported by the Swedish Foundation for Strategic Research. The team included Ali Shtarbanov, Hila Mor, Ken Nakagaki and Jack Forman of MIT; Kristina Hook of the Royal KTH Institute of Technology; and Karen Modrei, Seung Hee Jeong and Klas Hjort at Uppsala University in Sweden.