Strain sensor based on polyurethane/carbon nanotube elastic conductive spiral yarn with high strain range and sensitivity

Wearable flexible electronic strain sensor devices have gained significant attention in recent years due to their potential for detecting human motion in various scenarios. However, the development of strain sensors with high sensitivity across a wide range of strains remains a major challenge. We present herein a novel strain sensor based on a graded structure thermoplastic polyurethane (TPU)/carbon nanotube (CNT) composite yarn with significantly enhanced mechanical performance imparted by the designed structure. The twisted CNTs/TPU spiral yarn demonstrated a fracture elongation of up to 1066% while maintaining charge conductivity under high-strain conditions. Moreover, it exhibited sensitive changes in resistance versus tensile strain, excellent repeatability, and stability. As a strain sensor, it achieved a gauge factor (GF) of 67.2 within a strain range below 50%, reaching 51.7 in a strain range exceeding 150%. With a fast response time of 0.12 s, it enabled accurate identification of movements in different body parts. These findings highlight the broad application potential of the designed spiral yarn strain sensor in areas such as human motion monitoring and human-computer interaction.HighlightsPrepares a flexible strain sensor with graded-structure (CNT-fiber-yarn).Shows high sensitivity and a wide strain response rangeReveals the conductive model of strain sensor. Preparation, mechaincal and sensing performance, conductive model of CNTs/TPU twisted yarn.image