(a) Schematic illustration of the multifunctional wearable device. ( b) Schematic diagram of signal transmission and processing for thermotherapy of arthritis. (c) Image of the fabricated multifunctional wearable device. (d) Demonstrating flexibility and stretchability.
Researchers from Dalian University of Technology, China, have developed a flexible, wearable thermotherapy system. This multilayered device integrates temperature and humidity sensors with a thin gold-based heater on a stretchable polyimide film. Designed for real-time, automatic use, it responds to environmental cues and body movement, providing personalized thermal treatment for arthritic joints. The system marks a step forward in wearable health technology, addressing the limitations of conventional devices and offering patients a discreet, reliable tool for daily therapy and protection in varying conditions.
At the heart of the system is a kirigami–serpentine structure–an origami-like pattern that enhances flexibility and stretchability. Layered with an Au temperature sensor, Poly (3,4-ethylenedioxythiophene PEDOT)-based humidity sensor, and Joule heater, the device conforms closely to joints, such as knees, and performs reliably during movement. Using real-time data processed by a flexible circuit and Bluetooth-enabled feedback loop, the system can adjust heat output within 1 second, maintaining temperatures with less than 0.1°C variation at 45°C.
This innovation supports multiple applications: programmable on-demand therapy with customized heat cycles; daily thermal protection that automatically activates in cold weather; and moisture control to combat joint-stiffening humidity. On-body tests showed the heater could raise local skin temperature even outdoors, while humidity levels dropped steadily during use. Most strikingly, the team used photoplethysmography (PPG) to measure blood flow and confirmed that thermotherapy via this system significantly boosted local perfusion–an essential factor in pain relief. The design also proved durable through 1,000 plus use cycles, remaining accurate during walking, stretching, and running. By combining high precision with real-world practicality, this soft, wearable system delivers clinical-grade function in a form factor that patients can use every day.
Its modular design, environmental responsiveness, and soft mechanics make it well-suited for integration into clothing, bandages, or therapeutic garments. Additionally, the same sensing-feedback-heating architecture might be adapted for wound care, smart rehabilitation, or ambient-responsive materials.
