5/19/2026 Taylor Parks
Written by Taylor Parks
An international research team has been developing a low-cost, wearable wireless system design to monitor the human knee during rehabilitation.
The ongoing collaboration includes University of Illinois Grainger College of Engineering professor Elizabeth Hsiao-Wecksler (mechanical science and engineering) and associate professor Girish Krishnan (industrial and enterprise systems engineering), Dr. Phuong Cao from Illinois’ National Center for Supercomputing Applications, and assistant professor Mai Thanh Thai from the College of Engineering and Computer Science at Vietnam’s VinUniversity (VinUni). Other coauthors include associate professor Thanh Nho Do and postdoctoral fellow Phuoc Thien Phan from the Graduate School of Biomedical Engineering at UNSW Sydney in Australia. The team recently published their findings in Nature’s Scientific Reports. Graduate students Nhu An Phan and Sy Trung Ngo at VinUni are first authors on the publication.
Slated for funding through 2032, the project is supported by the VinUni-Illinois Smart Health Center, a collaboration between VinUni and the University of Illinois Urbana-Champaign. The purpose of the project is to conduct research on novel sensing and informatics with the goal of providing widely accessible health monitoring worldwide.
The team’s device, KNEESENSE, uses a custom-designed wearable hydraulic filament sensor (WHFS) to monitor the angle of the knee joint during real-time rehabilitation work. The foundation for the WHFS design originated with Thai’s PhD dissertation research.
“The key innovation of our work lies in the hydraulic filament sensing mechanism, which enables accurate knee angle monitoring while remaining soft, lightweight, and comfortable for users,” Thai explained. “By combining a silicone tube with a spring-based structure, we can translate pressure changes into precise motion data without restricting natural movement.”
The WHFS is integrated into a knee pad and paired with a wireless data acquisition (DAQ) unit, which transmits joint angle data to a mobile application. With the WHFS-and-DAQ system costing less than $30, the device provides a low-cost, user-friendly solution to patients whose only accessible rehabilitation option may be to do it themselves from home.
“By integrating real-time monitoring with a user-friendly mobile interface, we aim to empower patients to take an active role in their rehabilitation journey,” said Thai, noting that the system achieves strong performance metrics despite its low cost, including high sensitivity, low hysteresis, and reliable durability, with minimal signal degradation even after repeated use.
“KNEESENSE presents a cost-effective solution to reliably sense the knee angle in a non-intrusive fashion,” said Krishnan, who helped to refine the WHFS and optimize its performance by supporting modeling and analysis. “Unlike existing wearable knee angle sensors, which may impede natural motion or suffer from inaccuracy for the full working range of motion, KNEESENSE uses flexible silicone-based tubes and an incompressible fluid whose pressure can be accurately mapped to joint angle.”
The device comes as a welcome new solution not just for sports-related injuries but also for promoting a lower extremity rehabilitation ecosystem in developing countries that may suffer from accessibility issues.
“This technology could be a game changer for patients who can use gamified biofeedback for rehab,” Krishnan said. “It reduces burden on therapists and can be used to track gait changes among older adults.”
For Hsiao-Wecksler, the project was a natural fit.
“I’m interested in helping people with disabilities and looking at gait rehabilitation, and being able to create a new wearable sensing device falls squarely in my research interests,” she said. She now advises mechanical engineering PhD student Linh Dao, who recently joined the project to investigate the optimal fluid for long-term use in the sensor (the current prototype uses water, which has posed challenges) as well as understanding the impact of long-term cyclic loading on the device.
Beyond the research aspect of the project, Hsiao-Wecksler appreciates the opportunity to gain a new perspective and learn from her collaborators.
“I think it’s really exciting to be able to work with people in Vietnam and to understand their educational experience,” she said.
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Elizabeth Hsiao-Wecksler is the Grayce Wicall Gauthier Professor in the Department of Mechanical Science and Engineering. She holds affiliate positions in the Department of Industrial & Enterprise Systems Engineering and Department of Bioengineering as well as the Carle Illinois College of Medicine, Beckman Institute and Coordinated Science Laboratory.
Girish Krishnan is an associate professor in the Department of Industrial & Enterprise Systems Engineering. He holds affiliate positions in the Department of Mechanical Science and Engineering, Carle Illinois College of Medicine, the Center for Digital Agriculture and the Center for Autonomy.