Wireless, flexible, self-powered sensor to analyze head impact kinematics

Abstract

This work presents a prototype of a wireless, flexible, self-powered sensor used to analyze head impact kinematics relevant to concussions, which are frequent in high-contact sports. Two untethered, paper-thin, and flexible sensing devices with piezoelectric-like behavior are placed around the neck of a human head substitute and used to monitor stress/strain in this region during an impact. The mechanical energy exerted by an impact force --varied in locations and magnitudes-- is converted to pulses of electric energy which are transmitted wirelessly to a smart device for storage and analysis. The wireless prototype system is presented using a microcontroller with an integrated Bluetooth Low Energy module. The static and dynamic characteristics of the transmitted signal are then compared to signals from accelerometers embedded in a head substitute, to map the sensor’s output to the angular velocity and acceleration during impacts. It is demonstrated that using only two sensors is enough to detect impacts coming from any direction; and that placing multiple external sensors around the neck region could provide accurate information on the dynamics of the head, during a collision, which other sensors fail to capture.