Researchers in Hong Kong and mainland China have developed a lightweight, battery-free neural prosthesis designed to assist people with mobility difficulties, including stroke survivors, in walking more naturally. The device harnesses energy generated by the wearer’s own movements to stimulate muscle contractions electrically, aiding ankle flexion and improving gait patterns.
The team, led by experts from the Hong Kong University of Science and Technology (HKUST) and Hong Kong Polytechnic University, described the innovation in a recent paper published in the journal Nature Communications. The prosthesis operates without external batteries or sensors, activating automatically during walking through a mechanically coupled system that both harvests energy and delivers electrical stimulation.
Stroke survivors often experience foot drop, a condition that impairs the ability to lift the front of the foot, increasing the risk of falls and limiting mobility. Conventional solutions, such as rigid ankle braces, typically constrain movement rather than restore natural flexion, and may lead to muscle atrophy over time. While robotic exoskeletons have shown promise in assisting mobility, their complexity, bulkiness, and need for calibration have posed challenges for everyday use.
The newly developed device addresses these issues by integrating seamlessly into standard footwear and requiring minimal donning time, allowing for practical application beyond controlled laboratory settings. In controlled treadmill and outdoor walking tests, stroke survivors showed immediate improvements, with stride length and walking speed increasing significantly. Outdoor trials recorded a 67.3 percent increase in walking distance and a 43.5 percent boost in walking speed.
The device functions by capturing mechanical energy from the wearer’s less affected leg through a component embedded in the shoe. This energy powers a small neurostimulator attached around the calf of the affected leg, which then uses electrical impulses to stimulate muscle contractions, facilitating ankle movement. According to Pan Qiqi, a lead author and professor at Huazhong University of Science and Technology, this approach contrasts with exoskeletons, as it actively helps rehabilitate muscle function rather than merely compensating for lost motor capabilities.
The research team emphasized that the device aims to support natural gait patterns rather than replace or restrict them, representing a different strategy in rehabilitation technology. Although the prototype did not completely eliminate foot drop during outdoor use, it produced notable gait improvements.
Experts acknowledged that further optimization is needed, including refining stimulation control to expand the device’s effectiveness across a broader range of patients. Study participants expressed a strong desire for accessible rehabilitation tools that encourage mobility and social engagement, underscoring the importance of solutions that support everyday activity and community involvement for stroke survivors.
Strokes remain a leading cause of death and long-term disability globally, with one in four adults predicted to suffer a stroke during their lifetime. This development offers a promising step toward enhancing mobility and quality of life for those affected.