Wearable sensors have the potential to provide new methods of non-invasive physiological measurement in real-time. This work presents an alternative to the current clinical measurement of spinal flexion; the modified Schober’s test. The accuracy of the test is determined by each clinician, which causes a large tendency towards error [1]. By implementing a strain sensor as an alternative to the measuring tape currently used, it is proposed that inter-observer error would be reduced and more consistent measurements would be provided over time.
Herein, two types of textile based sensors were tested for use in this application; a knitted spandex cylindrical structure with integrated carbon nanotubes (CNT) and a flat, knitted piezoresistive fabric (KPF) knitted with Lycra® [2]. Of each type, numerous samples were fabricated with varying length, width, core size, tension and knit direction. Each sensor was tested for resistance changes versus strain in the laboratory where it was clear that KPF sensors knit under high tension provided accurate and reproducible electrical properties. All varieties of CNT sensors showed inconsistent resistance measurements over time, rendering them unsuitable for use of such precise measurements. After calibration, it is proposed that these sensors can be easily integrated into a wearable device to be used in a clinical setting.