New wearable system for step-counting telemonitoring and telerehabilitation based on the Codivilla spring

During stroke rehabilitation at home, the most used equipment is the Codivilla spring for both bilateral and one-side stroke damage. A novel Codivilla spring prosthesis has been electronically sensorized in order to allow new functionalities pertinent to telerehabilitation, such as the step counting and biofeedback mapping of gait-phases. The principal elements of the electronics are a couple of force-sensing resistors affixed in the plantar area of the prosthesis, and a wearable unit with a microprocessor-based on Microchip technology (Microchip Technology, Inc., Chandler, AZ) for data processing and a telemetric system based on Aurel technology (Aurel, Modigliana, Italy) for data tansfer. While ambulating, the foot-sensing resistors detect the pressure of the foot-tip and heel. The microprocessor provides step-counting on the basis of an algorithm. The microprocessor also drives two vibrotactile actuators (one at the foot-tip and the other at the heel). These actuators are fixed at the level of the belt directly in contact with the skin and give biofeedback mapping of the gait-phases to the patient wearing the prosthesis, who can then walk without looking at his or her feet. The sensorized prosthesis was tested on six subjects undergoing stroke rehabilitation at level 2 of the Tinetti test. These subjects performed five repetitions of 100 steps with three different instructions (fast, slow, and normal). The mean error was lower than 0.6%. A test conducted by means of Cosmed devices (Cosmed USA, Chicago, IL) also showed that the biofeedback function provided by means of the actuators diminished the energy expenditure by 0.7% in mean value. The next phase will be the optimization of the equipment for long-term medical application in a patient's home.