Influence of Fiber Orientation on the Electrical and Mechanical Properties of Wearable Sensors Based on Smart Materials

Abstract

Wearable textile sensors offer promising applications in fields such as rehabilitation, robotics, and human motion analysis. However, the influence of fabric mechanical properties and fiber orientation on sensor performance remains insufficiently explored. This study evaluates the electromechanical characteristics of piezoresistive and conductive fabrics to assess their suitability for strain sensing. Seven widely used materials were subjected to tensile testing, with statistical t-tests confirming significant directional differences in 10 out of 14 mechanical parameters (yield point and Young’s modulus). A detailed electrical characterization was conducted on Silitex due to its unique structure and elasticity up to 80% strain. Static and dynamic tests revealed a strong dependence of resistance values on fiber orientation, with notable differences in hysteresis error after a 20% pre-strain between wale ( 13.0±0.3% ) and course ( 6.5±2.1% ) directions. However, course direction has a wider working range ( 51.9% ) and higher sensitivity ( -3.3% ) than wale ( 86.3% and -18.8%, respectively), further underlying the dependence of metrics on fiber orientation. The findings on the materials are based on tests conducted under controlled conditions, specifically, a purely tensile deformation state and using a simplified geometry. The results of this study do not necessarily generalize to all wearable sensor applications; however, they may still provide valuable indications for optimizing designs in other scenarios more closely resembling the typical use cases of wearable sensors.