AI-empowered wearable rehabilitation device: PolyU develops closed-loop sensory wristband to enable personalised rehabilitation for stroke patients
Stroke ranks as the fourth leading cause of death in Hong Kong. Between 2001 and 2021 there was a distinct trend towards younger onset ages of stroke, which has exerted a profound impact on the public health system and the families of patients. To address the challenges of disability and slow rehabilitation progress associated with hemiparesis, a common sequela of stroke, a research team at The Hong Kong Polytechnic University (PolyU) has applied intelligent closed-loop mobile technology to develop a new-generation wearable rehabilitation device, the “Remind-to-Move” (RTM) sensory wristband. Complemented by a mobile application, the device delivers instant feedback to users and automatically adjusts treatment regimens, thereby enabling more personalised home-based rehabilitation training.
Led by Prof. Kenneth FONG, Associate Head of the Department of Rehabilitation Sciences and Director of the Research Centre for Assistive Technology at PolyU, the RTM sensory wristband is specifically designed for patients with hemiparesis due to neurological conditions such as stroke or cerebral palsy. By emitting vibration signals, it reminds patients to perform exercises as instructed by their therapists. The latest version is enhanced with a “closed-loop system” that integrates artificial intelligence (AI), neuroscience and kinematic technologies. By real-time comparison of the movement patterns of the hemiparetic limb with its non-affected counterpart, the system automatically adjusts training parameters such as frequency and intensity, thereby improving the patient’s mobility more effectively.
Prof. Fong said, “When facing with limb dysfunction, stroke patients tend to unconsciously rely on their non-affected limbs to complete daily activities, gradually reducing the use of their hemiparetic side. This leads to ‘learned non-use’ of the affected limb and hinders its recovery. The RTM sensory wristband developed by PolyU directly addresses this critical issue. By sensing and analysing the user’s movement patterns, it emits timely signals to guide patients in actively using their hemiparetic limbs for home-based rehabilitation training. In the long run, it can effectively improve patients’ sensory awareness and mobility of the affected limb, facilitating their faster return to normal daily life.”
Prof. Fong has led his team in the development of “RTM therapy” using wearable rehabilitation devices since 2009. The RTM wristband is the world’s first rehabilitation intervention specifically designed to promote use of the hemiparetic arm in adult stroke patients and children with cerebral palsy. Earlier iterations adopted an “open-loop system” with fixed, preset therapy and were proven to effectively reduce “learned non-use” of the hemiparetic upper limb. To achieve more personalised rehabilitation outcomes, the team has upgraded the new-generation wristband to a “closed-loop system”, which sends cues based on the user’s actual arm movements and provides real-time feedback.
Research findings showed that both the open-loop and closed-loop RTM systems improved hand function and movement frequency. Notably, the close-loop system exhibited more prominent advantages—compared to participants in the open-loop group, those using the closed-loop system demonstrated higher movement frequency and more marked improvements in hand function. “By using AI-enabled technology to provide real-time feedback, the closed-loop system can tailor exercise training to personal needs,” Prof. Fong explained. “The data collected also help us analyse the interaction between exercise programmes and external assistive devices, which is conducive to designing more targeted treatment protocols to promote neuroplasticity. Our research provides a novel approach for the treatment of hemiparetic upper limb dysfunction and holds great significance for popularising tele- and home-based rehabilitation.”
Looking ahead, the team aims to integrate the closed-loop RTM mechanism into a broader range of more wearable rehabilitation devices to further enhance therapeutic efficacy. The related study has been published in the journal Wearable Technologies.
Prof. Fong’s research is supported by the Research Impact Fund from the Research Grants Council. Both the open-loop and closed-loop RTM devices have been patented in the United States and the Chinese Mainland, and the previous generation of the open-loop RTM devices has been adopted for over 10 years by 16 public hospitals in Hong Kong and international institutions such as the Kessler Rehabilitation Center in the United States, while its use has been extended to Singapore and the Chinese Mainland.
The research team is currently recruiting stroke patients to participate in a clinical study of the new version of the RTM wristband. Participants will wear the wristband and engage in a four-week telerehabilitation programme under the guidance of a professional occupational therapist. The study aims to gain deeper insight into upper-limb activity patterns and evaluate the effectiveness of the intervention.
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