RESUMEN
Freedom of neck range of motion has been identified for decades as an important indicator of neck health. In the past, neck motion has been measured in clinical settings using straight-plane movements that do not represent real-world 'ecological' performance. The tools currently used are low-fidelity analog or digital tools that rely greatly on the orientation of the person with respect to gravity, or the evaluator's ability to accurately align protractor arms with key surface markers for angle measurement. A possible solution lies in the use of wearable sensors for tracking the motion of the neck without clinical instruction. For this purpose, the focus of this paper is on the assessment of a commercially available stretch sensitive sensor, C-Stretch® against a gold standard for motion tracking. The sensor's accuracy and agreement for measuring neck rotations were evaluated. The results show that the stretch sensitive sensor was accurate with an average RMSE of 5.86° (SD=$4.38^{\circ}, \mathrm{n}=2$) and highly correlated $r=0.88-0.99,(p\lt0.01)$ with Aurora, an electromagnetic tracking system. This work may lead to using wearable sensors as a cost-effective, lightweight, and safe alternative to assess real-world neck range of motion for clinical application.