A Low-Cost Vibratory Stimulus System to Mitigate Freezing of Gait in Parkinson's disease.

Freezing of gait (FOG) is a symptom of advanced Parkinson's disease (PD) that affects the quality of life of these patients. This paper presents a new low-cost stimulus system to support the patient response to FOG episodes by using a vibratory cue. Freezing episodes are automatically detected by using an inertial measurement unit (IMU) placed on the patient's right ankle and a pressure sensor embedded into a shoe insole to reduce false-positive episodes. This data is transmitted using Bluetooth technology to a PC and once a freezing event is detected, a vibratory stimulus is produced on the left sole by triggering a micromotor at 275 Hz, which is embedded into the left shoe insole. The entire system was evaluated over a walking circuit designed to provoke FOG events during acquisition of kinematic data. The average time to perform the complete circuit for PD patient is around 146 seconds (without stimulations) and 96 seconds with vibratory stimulation system; therefore showing that time diminishes by 34%.