It’s Time to Do Some Sole Searching

There are many medically relevant biological signals that can be measured throughout the body. Some of these are obvious, like heart or respiration rate and blood pressure. But others are much less obvious, like the patterns of pressure we put on our feet as we stand, walk, or run. This may not seem like it would reveal anything of interest, but since these actions require coordinated inputs from the skeletal, nervous, and muscular systems, these patterns can reveal one’s risk of developing conditions like Parkinson’s disease, stroke, or any number of orthopedic problems.

The most straightforward way of collecting this information is through the use of smart insoles equipped with sensors. Yet, despite their utility, these devices are quite rare today because existing systems tend to suffer from issues with poor accuracy and short battery life. That may change in the near future, however, thanks to the work of a team at The Ohio State University. They have developed a new type of smart insole that is accurate, durable, and never needs to be recharged.

The new system is built around 22 miniature pressure sensors distributed from heel to toe. These sensors can precisely measure the distribution of pressure across the sole during different types of movement. Whether a person is standing still, walking, or running, the insole captures this data in real time and transmits it to a smartphone via Bluetooth for visualization and analysis.

Since few people are looking for yet another device to keep charged up, and no one really wants to plug in their shoes, it is powered by flexible solar cells embedded on the tops of the shoes. This eliminates the need for external charging or frequent battery replacement.

To make sense of the pressure data, the insole incorporates machine learning into its data processing pipeline. That enables it to classify eight distinct types of motion — including static states like sitting and standing, and dynamic ones like walking, running, or squatting. This ability to distinguish between movement types in real time opens the door for a wide range of applications, from posture correction and fitness training to early diagnosis and monitoring of medical conditions.

One of the most promising applications of the technology is in healthcare, where the insole could help detect early signs of neurological conditions like Parkinson’s disease or physical ailments like plantar fasciitis and diabetic foot ulcers. Because pressure patterns differ based on how a person moves, the system can flag deviations from normal behavior that may indicate the onset of disease or risk of injury. For example, walking typically involves sequential pressure from heel to toe, while running creates simultaneous pressure across most of the foot. Subtle changes in these patterns could serve as early warning signs.

The researchers believe that the device could be commercially available within the next three to five years. Future development will focus on expanding the device’s capabilities to include gesture recognition and testing across a more diverse population to ensure accuracy across different walking styles and foot anatomies.