Smart insoles are part of a new generation of medical technology set to revolutionise rehabitation. Whether it is recharging batteries of providing useful biofeed back the gait cycle can be used to good effect with new micro-technologies. On average a sedentary person takes between 1,000 to 3,000 steps a day (approximately 1320 steps in a kilometre). Carefully positioned sensors in shoe inserts can harness energy generated with each step and transmit this to recharge a simple battery. Normally this energy is lost as heat. However with technology up to 20 watts of electricity can be generated, and stored in an incorporated rechargeable battery. Mechanical researchers, Tom Krupenkin and J. Ashley Taylor ( University of Wisconsin-Madison ) developed an energy-harvesting technology they call "reverse electrowetting," and SolePower is a special insole fitted with sensors and connected to a battery on the top of a shoe or around the ankle through the laces. The action of walking generates enough energy to fully charge an iPhone after 8km (or five miles). Besides directly powering a phone, the device could also serve as a mobile WiFi hotspot, linking the phone to a wireless network. Having its own hotspot constantly nearby could drastically increase the phone's battery life by up to ten times claim the inventors.
Prof. Stacy Bamberg (University of Utah) is a mechanical engineer who is developing the Rapid Rehab system i.e. a “smart” insole paired to a smartphone app, designed to provide users with bio-feedback on how they walk. The gel insole incorporates two force-sensitive resistors to measure pressure when the patient’s foot is on the ground. It also contains an accelerometer for detecting leg movement, and a gyroscope for determining the angle and position of the foot. Data from all of those sensors is wirelessly transmitted to a smartphone. A custom app then creates a real-time profile of the patient’s gait. Any problems with their walking patterns can be rectified via visual, audio or sensory feedback. The advantage of in-shoe technology is according to the experts is it can be used anywhere at any time, and allows patients to self monitor. The hope is the the system will be commercially available in a few years time.