Smart Shoe

An electronic insole catches imbalance early

Most summer interns at NASA don't end up inventing life-­saving devices. But Erez Lieberman, a graduate student at the Harvard-MIT Division of Health Sciences and Technology, helped come up with a new application for technology used to test the balance of returning astronauts: an insole that can detect imbalance in the elderly.

Erez Lieberman developed the iShoe, which monitors the pressure distribution of a patient’s foot and informs a doctor of chronic imbalance. Credit: Donna Coveney/MIT

Poor balance can be fatal in older ­people, says ­Lieberman: his own grandmother was among those who had falls from which they never recovered. While working at NASA with bulky, phone-booth-like devices that measure balance, Lieberman and his colleague Katharine Forth had the idea of developing a portable detector that was more sensitive and less expensive. The result was the iShoe, an insole equipped with sensors that constantly monitor a wearer's balance. It should be able to diagnose chronic imbalance earlier than simple approaches such as asking a patient to stand on one foot.

The system represents a significant advance over other methods of balance detection, says Lieberman. He and Forth equipped a standard insole with acceler­ometers, pressure sensors, and other measuring devices. They also installed a wireless transmitter to communicate with a computer running balance analysis software that they developed.

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The iShoe records weight distribution and determines a person's center of gravity, which the software represents on-screen as a red orb trailed by green. In people with good balance, the center of gravity constantly shifts but "moves in a relatively characteristic way" that the iShoe can identify, says Lieberman, balancing a marker to demonstrate the control a person needs to resist gravity and keep from falling.

Lieberman envisions elderly people wearing a $100 to $200 iShoe as an everyday insole. A doctor would query the insole twice a year at checkups; if the device detected poor balance, the doctor would look for the cause, which could be failing vision, deterioration in the muscles or nerve endings of the foot, or inner-ear problems. Eventually, the iShoe might even be able to help doctors identify the problem, since different causes of imbalance are characterized by different patterns. The iShoe could also be paired with visualization software designed to improve balance; it could even be used in video games, such as a basic skiing simulator that ­Lieberman developed with Harvard's Qian Yang, another member of the iShoe team. The team plans to test the iShoe in elderly subjects this fall.