Repeatability and Reliability Evaluation of a Wireless Head-band Sensor

OBJECTIVES
The objective of this study to examine the reliability and repeatability of the headband sensor in comparison with the gold standard 3 linear and 3 angular rate sensors placed at the center of gravity of the Hybrid III dummy head during drop tests.
METHODS
A SIM-G headband sensor was attached to a Hybrid III dummy head and neck which was equipped with a triaxial accelerometer and 3 angular rate sensors. Linear acceleration and angular rate was sampled at 10,000 Hz while the SIM-G headband was sampled at 1000 Hz and 800 Hz respectively. A drop test was developed to test between 20 to 140 g and consisted of a total of 400 impacts in four locations, left occipital, right occipital, frontal and rear impacts with 100 impacts per location. Multiple tests were performed at the same height to verify the reliability of the devices. SIM-G data and the reference sensors were compared for validity.
RESULTS
The reliability measured by Cronbach's alpha showed very high repeatability for the SIM-G (α = 0.97-0.99). However, the validity measurement, Pearson's Correlation coefficient (r), showed a weak to very strong relationship (r=0.2-0.9).
CONCLUSIONS
While using the SIM-G sensor to help monitor head impact, the weak to strong validity of the SIM-G sensor must be carefully considered by the clinicians or researchers as a serious limitation.