Pressure sensor yarns with a sheath-core structure using multi-fiber polymer

Textiles are expected to be used as a platform for soft and flexible electronic devices that closely fit the human body and curved surfaces, which are strongly demanded in our highly networked society. This study presents pressure-sensing double-ply yarns in which two independent conductive yarns are insulated using covering yarns of multi-fiber polymer to form a sheath-core structure. When force is applied to the double-ply yarn, the electric resistance between the two conductive yarns decreases significantly due to the deformations caused by the elasticity of the multi-fiber covering, and the applied force can be detected from the resistance change. The proposed sensor yarn has a distinctive characteristic of being sensitive to compressive and tensile strains but extremely insensitive to free bending without tension. We fabricated fabrics embedded with the sensor yarns and demonstrated that they can sense external forces as well as the sensor yarns, although sensitivity is decreased. These yarns and fabrics can be implemented in soft electronic devices such as wearable devices and biological sensors that must be fitted to human bodies or curved surfaces. This work contributes to the development of smart textiles that can be applied to flexible, wearable electronics. • Pressure-sensing, highly supple, double-ply yarns with a sheath-core structure. • Sensor resistance changes due to elasticity of multi-fiber polymer. • Yarn that’s sensitive to compressive force and tensile stress. • Sensing by woven and knitted fabrics with embedded pressure sensor yarns.