Wireless, Self-Powered Smart Insole to Improve Personal Health Monitoring

Millions of people experience challenges with ambulatory functions, which include activities like walking, running, and climbing stairs. Although there has been an increasing interest in creating wearable insole-based pressure systems in recent years, many previous prototypes faced issues such as limited energy and unstable performance. Now, a new smart insole system that monitors walking in real time may offer a solution to improve posture and provide early warnings for conditions ranging from plantar fasciitis to Parkinson’s disease.

This new system, developed by researchers at The Ohio State University (Columbus, OH, USA), uses 22 small pressure sensors and is powered by small solar panels placed on the tops of shoes. It provides real-time health tracking based on an individual's walking patterns, which are as unique as a fingerprint. The collected data is then transmitted via Bluetooth to a smartphone for quick, detailed analysis, as outlined in the study published in Science Advances. To address limitations in previous designs, the OSU research team ensured that the system is durable, offers high precision in data collection and analysis, and can provide reliable power. The system also incorporates artificial intelligence (AI) through an advanced machine learning model, enabling the device to recognize eight different motion states, ranging from static postures like sitting and standing to more dynamic movements like running and squatting.

Additionally, the materials used in the insoles are flexible and safe, similar to those found in smartwatches, making the device low-risk for continuous use. After the solar cells capture sunlight, the energy is stored in small lithium batteries, which are harmless and do not interfere with daily activities. By distributing sensors from toe to heel, the researchers can track the pressure exerted on different parts of the foot during activities like walking versus running. When walking, pressure is applied sequentially from the heel to the toes, while during running, most sensors experience pressure simultaneously. Furthermore, walking generates pressure over about half of the total time, whereas running applies pressure for just a quarter of the time.

In healthcare, the smart insoles could aid in gait analysis to detect early signs of foot pressure-related conditions, such as diabetic foot ulcers, musculoskeletal disorders like plantar fasciitis, and neurological conditions such as Parkinson’s disease. The system also uses machine learning to classify various motion types, providing opportunities for personalized health management, including real-time posture correction, injury prevention, and rehabilitation monitoring. The researchers also see potential for customized fitness training with this technology. According to the study, the smart insoles showed no significant performance degradation after undergoing 180,000 cycles of compression and decompression, demonstrating their long-term durability. Researchers anticipate that this technology will likely be commercially available within the next three to five years. Future advancements will focus on improving the system’s gesture recognition capabilities, which will be enhanced through further testing on more diverse populations.

“Our bodies carry lots of useful information that we’re not even aware of,” said Jinghua Li, co-author of the study and an assistant professor of materials science and engineering at The Ohio State University. “These statuses also change over time, so it’s our goal to use electronics to extract and decode those signals to encourage better self-health care checks. Our device is innovative in terms of high resolution, spatial sensing, self-powering capability, and its ability to combine with machine learning algorithms. So, we feel like this research can go further based on the pioneering successes of this field.”