Reviewed by Lexie CornerApr 29 2025
Researchers at Shinshu University have developed a new design for more robust and flexible fiber sensors in wearables. They created a fiber sensor based on the structure of DNA. Traditional fiber sensors used on body joints often experience electrode malfunction at both ends after extended use. The proposed double-helical design addresses this limitation.
Durable DNA-inspired fiber sensor for wearables. Researchers have developed a flexible fiber sensor with a double-helical structure that places both electrodes on one end. This design improves durability, allowing the sensor to endure repeated stretching and bending, and makes it easier to integrate into wearable devices, especially for use on body joints. Image Credit: Associate Professor Chunhong Zhu from Shinshu
Flexible fiber sensors are commonly used in smart wearable devices because of their compact size and lightweight nature, making them ideal for daily use. However, mechanical limitations restrict the performance of current designs, particularly when positioned at joints.
When placed on joints such as fingers or knees, where frequent movement puts stress on connecting wires, traditional fiber sensors with electrodes at both ends are prone to damage or inaccuracies in readings.
Effective electrode design is critical to the performance and lifespan of wearable sensors. But in one-dimensional fiber sensors, this has long been a challenge. Our design addresses this issue directly.
Chunhong Zhu, Associate Professor and Study Lead Author, Institute for Fiber Engineering and Science, Shinshu University
The stability of DNA's double helix, maintained by hydrogen bonds between complementary base pairs, inspired the researchers. They created a stable structure by twisting two specially designed coaxial fibers together. Coaxial wet-spinning is used to produce each fiber, which has a conductive inner core and an insulating outer layer.
The core is composed of multi-walled carbon nanotubes (MWCNTs), while the outer layer is made of thermoplastic polyurethane (TPU) and titanium dioxide (TiO2) nanoparticles, which provide strength and fluffiness to the fibers.
After heat treatment, complex wiring at both ends is unnecessary, as the two fibers naturally form a double helix with built-in positive and negative terminals on the same end, addressing a common issue in traditional designs.
The TT/MT dual-helical fiber has two electrodes at one end and a free end with no electrodes, greatly simplifying the wiring of flexible sensors.
Mr. Ziwei Chen, Study Co-Author, Shinshu University
With a diameter of less than 1 mm, the TT/MT dual-helical fiber sensor is exceptionally thin and can be easily integrated into wearable textiles. It also demonstrated high durability, withstanding over 1,000 stretching cycles and extending more than 300 % of its original length without breaking in lab tests.
Because both electrodes are positioned on the same side of the sensor, it can be used across joints without the risk of wire damage. This is achieved by placing the electrode side on areas with limited movement, such as the back of the hand, cheeks, or knees, where the sensor is less likely to experience stress from frequent movement. This allows for the tracking of facial expressions, gait, finger gestures, and even breathing patterns during sleep.
In one experiment, the researchers embedded the sensor in a glove and trained it to recognize finger movements using a machine-learning model. The glove achieved a 98.8 % accuracy rate in identifying six common hand gestures. In another test, the sensor detected how long each finger pull lasted and used that to send Morse code wirelessly, showcasing its potential as a tool for assisting people with disabilities.
The researchers also suggest that the design could be used in wearables with Bluetooth connectivity, enabling real-time remote monitoring for sports training and rehabilitation. For high-risk activities like mountaineering, the team envisions these sensors integrated into clothing that could send emergency alerts in the event of accidents, falls, or medical conditions like hypoxia.
The researchers hope that this innovative design will inspire the development of the next generation of intelligent fibers that are sensitive, durable, and easily incorporated into everyday clothing.
Our design strategy, exemplified by the TT/MT dual-helical fiber highlighted in our study, also provides a versatile approach that can inspire the development of various intelligent fibers tailored for different applications.
Chunhong Zhu, Associate Professor and Study Lead Author, Institute for Fiber Engineering and Science, Shinshu University
Journal Reference:
Chen, Z., et al. (2025). Structure and Wiring Optimized TT/MT Double‐Helical Fiber Sensors: Fabrication and Applications in Human Motion Monitoring and Gesture Recognition. Advanced Science. doi.org/10.1002/advs.202416564.