Research Bits: May 20

Smart t-shirt with sound waves

Researchers at ETH Zurich developed a smart textile that uses acoustic waves passed through glass fibers to measure touch, pressure, and movement. The researchers said that using acoustic waves rather than electronics makes measurements more precise with low power consumption and the textiles lighter, more breathable, and easier to wash. It also uses readily available materials.

Glass fibers are woven into the fabric at regular intervals, with a small transmitter that emits sound waves in the ultrasonic range at one end and a receiver that measures whether the waves have changed at the other. When a glass fiber moves as a result of things like body movement or breathing, the length of the acoustic waves passing through it changes as they lose energy. Each transmitter uses a different frequency, so minimal computing power is required to determine which fiber’s sound wave has changed, avoiding signal processing overload.

The device can be incorporated into a shirt, as the researchers did in the lab, or other types of clothing. Potential applications range from monitoring breathing in asthma patients to improving movement sequences in sports and translating sign language. The team plans to replace the glass fibers with metal to improve robustness. [1]

3D printing for soft smart fabrics

Researchers from Washington State University demonstrated a 3D ink printing method for creating smart fabrics that can withstand washing and abrasion.

Hang Liu, an associate professor in the Department of Apparel, Merchandising, Design and Textiles at WSU, said in a press release that much of the smart textile has focused on building technological functions into fabrics, without attention to the way fabrics might feel or fit. “The materials used, or the technology used, generally produce very rigid or stiff fabrics. If you are wearing a T-shirt with 3D printed material, for example, for sensing purposes, you want this shirt to fit snugly on your body, and be flexible and soft. If it is stiff, it will not be comfortable and the sensing performance will be compromised.”

To overcome this, the team used direct ink writing 3D printing technology to print solutions of the biodegradable polyester polybutylene succinate containing carbon nanotubes onto two types of fabric. Along with showing excellent electrical conductivity, the printed fabrics continued to perform well after 20 cycles of washing and drying, and the surfaces did not scratch or crack after 200 cycles of abrasion testing or 500 cycles of tensile cyclic testing. [2]

Double-helical fiber sensor

Researchers from Shinshu University developed a flexible fiber sensor with a double-helical structure that mimics the shape of DNA. Instead of an electrode at each end, the design places both electrodes on one end of the fiber, reducing strain during movement and improving durability.

The coaxial fibers were produced using coaxial wet-spinning. The conductive core of the fiber contains multi-walled carbon nanotubes, while the insulating outer layer includes thermoplastic polyurethane and titanium dioxide nanoparticles. Two fibers were then twisted together. After heat treatment, the two fibers naturally form a double helix with built-in positive and negative terminals on the same end, eliminating the need for complex wiring at both ends.

At less than 1mm in diameter, the team says the fiber sensor is suitable for integration into wearable textiles, where it can be placed across joints with the side containing the electrodes attached to areas with limited movement, greatly reducing the risk of the joint’s movement pulling the wire from an electrode at the opposite end. In lab tests, it withstood over 1,000 stretching cycles and extended more than 300% beyond its original length without breaking. The team also placed the sensor inside a glove and used it to recognize finger movements and hand gestures. They also see it being used in clothing for high-risk activities like mountaineering. [3]

References

[1] Wang, Y., Sun, C. & Ahmed, D. A smart acoustic textile for health monitoring. Nat Electron (2025). https://doi.org/10.1038/s41928-025-01386-2

[2] Zhao, Z., Liu, W., and Liu, H. Flexible and Durable Direct Ink Writing 3D-Printed Conductive Fabrics for Smart Wearables. ACS Omega 2025 10 (14), 14138-14149. https://dx.doi.org/10.1021/acsomega.4c11367

[3] Chen, Z., Qian, D., Xie, D., et al. Structure and Wiring Optimized TT/MT Double-Helical Fiber Sensors: Fabrication and Applications in Human Motion Monitoring and Gesture Recognition. Adv. Sci. 2025, 12, 2416564. https://doi.org/10.1002/advs.202416564