Engineered from noise-resistant, conductive threads, the advanced smart fabric could be used for health monitoring, athletic performance, and rehabilitation, according to research published in the journal Science Advances.
As a materials engineer at RIKEN, Sunghoon Lee merges his passion for sports with his drive for research. “Personally, I’m interested in baseball,” he says, noting that his team previously created a fingertip sensor to track pitchers’ movements.
Now, the group has developed a lightweight, comfortable textile designed to support health monitoring, enhance sports performance analysis, and aid rehabilitation.
Based at the RIKEN Center for Emergent Matter Science, Lee explains that the technology can precisely measure muscle activity across the body during movement. It could help clinicians monitor recovery more effectively, enable athletes to refine their performance, and allow researchers to deepen their understanding of biomechanics.
The fabric relies on electromyography (EMG), a technique that detects the faint electrical signals produced when muscles contract, showing how they engage during movement.
Because these signals are extremely weak—only a few millivolts—they are easily overwhelmed by electrical noise, which has limited the widespread use of EMG.
Noise-Free Measurements
Traditional EMG systems rely on bulky amplifiers or nearby wireless modules, which add weight and limit mobility. In contrast, the new flexible EMG textiles make it much easier to capture signals across the entire body, Lee explains.
A key element of these textiles is a naturally stretchable conductive material that detects muscle signals. In this study, Lee’s team used commercially available silver-coated nylon wound around a polyurethane core, though they are now working on developing their own stretchable wiring.
However, larger stretchable systems built with these conductors often pick up electrical noise caused by contact, movement, or interference from nearby electronic devices.
“These factors can produce a significant amount of noise,” Lee explains, “so we needed an effective shielding system to minimize it.”
To protect the signals from external interference, his team engineered a yarn with a three-layer structure: a conductive core fiber that transmits the signal, enclosed within a layer of polyurethane insulation.
The designers disperse silver flakes—tiny, highly conductive particles—within a fluoroelastomer, a flexible rubber-like polymer, to form the outer shielding layer. While the elastomer ensures stretchability, the silver flakes create an interconnected network that maintains conductivity even under strain. This high conductivity enables the shield to absorb and deflect electromagnetic interference away from the signal-carrying core.
Together, these materials create a seamless protective layer that can stretch without breaking, preserving its shielding performance even when extended to 120% of its original length.
Knitted Systems
The researchers incorporated the yarn into a knitted fabric equipped with electrodes and wireless EMG modules that decode and transmit the wearer’s muscle activity. To keep movement unrestricted, the modules are positioned at the waist.
During testing, the yarn stretched sufficiently to accommodate most joint motions while preserving its shielding performance. It also effectively reduced interference—“Even when someone pressed on the wiring, the signal stayed clean,” Lee notes.
In shoulder mobility tests, the shielding proved especially important for capturing signals during assisted, passive movements, such as those used in rehabilitation. Without it, electrical interference from another person’s touch disrupted the EMG readings.
Follow-up tests on lower-body muscles showed the system can handle dynamic movements. Using eight electrodes, the researchers successfully monitored four major lower-body muscle groups during activities like jumping, cycling, and running.
The garment resembles lightweight sportswear. “It’s like a thin inner layer,” Lee explains. “You actually feel quite comfortable wearing it.”
Repeated wear trials revealed no major signal loss, though washability remains an issue.
“The textile performs consistently after several wears,” Lee notes. “But washing this version can easily damage it, so we need a method to better protect the shielding layer.”
Customizing The Garment
The researchers’ next focus is on personalizing the garment. A one-size-fits-all design isn’t optimal for precise EMG monitoring, since muscle locations differ from person to person. While current prototypes suit average body shapes, achieving accurate measurements across diverse body types will require custom tailoring.
“We’re now focused on fully personalizing the textile for each individual,” Lee says.
He envisions using 3D body scans to digitally design and print electrode positions and wiring layouts tailored to a wearer’s anatomy. This approach would align electrodes precisely with target muscles, enhancing both signal accuracy and comfort.
It represents a move toward custom-fit smart garments—akin to bespoke athletic wear, but integrated with electronics.
Lee says the team intends to enhance sweat management and investigate sustainable materials like biodegradable elastomers and carbon-based conductors. He sees textiles as the ideal medium for wearable electronics, noting that clothing naturally covers broad areas, allowing full-body monitoring. Textiles also provide comfort, flexibility, and seamless integration into daily life.
“Textiles are an excellent platform,” Lee adds, “and now that we’ve solved the noise problem—a major challenge—this system can reliably track a variety of activities.”
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