Highly sensitive and stretchable strain sensors based on serpentine-shaped composite films for flexible electronic skin applications

Flexible strain sensors have received intensive attention owing to their wide application prospects in human activities monitoring, skin-mountable electronics, and intelligent robotic systems. Combining the synergistic effect of three-dimensional (3D) hybrid conductive networks and the serpentine-shaped sensing layer fabricated by engineering graphene nanoplates/carboxyl-functionalized multiwalled carbon nanotubes/silicone rubber (GNPs/MWCNTs/SR), a new type of flexible strain sensors is established with high sensitivity, stretchability, ultra-low detection limit, and excellent dynamic response characteristics demonstration. The facile preparation approach, plausible mechanism of tensile strain perception, and specific performance indexes of the integrated devices are elaborated effectively. The achieved strain sensors exhibit high sensitivity (GF -6.3-2675.5) with measuring strain up to 100%, an ultra-low strain detection limit of 0.05%, a rapid response time (similar to 46 ms), and the outstanding durability as well as stability over 2000 cycles. Importantly, such flexible strain sensors are utilized and successfully attached to different joints of the human body for motions monitoring implementation in real-time, enabling to be applied for various engineering applications in the microstrain-detection field. The highly sensitive, and stretchable flexible strain sensor developed by serpentine-shaped film of a GNPs/MWCNTs/ SR poises as a prospective candidate for wearable applications in real-time and high accuracy human motions detection, advanced human-machine interface, and intelligent robots.