A Highly Sensitive and Stretchable Yarn Strain Sensor for Human Motion Tracking Utilizing a Wrinkle-Assisted Crack Structure.

With the booming development of flexible electronics, the need for a multifunctional and high-performance strain sensor has become increasingly important. Although significant progress has been made in designing new microstructures with sensing capabilities, the trade-off between sensitivity and workable strain range has prevented the development of a strain sensor that is both highly sensitive and also stretchable. Here, a wrinkle-assisted crack microstructure is designed and fabricated via pre-stretching the multi-walled carbon nanotubes ink (CNTs ink)/polyurethane yarn (PU yarn). This designed structure originates from the mismatch in Young's modulus and elasticity between the CNTs ink and PU yarn during the stretching process. The structure endows the sensor with combined characteristics of a high sensitivity towards stretching strain (gauge factor (GF) of 1344.1 at 200% strain), an ultralow limit of detection (<0.1% strain), excellent durability (>10,000 cycles), a wide workable strain range (0-200%), and outstanding response and stability toward bending deformation. This high-performance strain sensor will see widespread improved performance across applications such as intelligent fabrics, electrical skins, and fatigue detection for full-range human motion monitoring.