An ultra-wide sensing range film strain sensor based on a branch-shaped PAN-based carbon nanofiber and carbon black synergistic conductive network for human motion detection and human–machine interfaces

Abstract

There is an urgent need to obtain low detection thresholds and wide sensing ranges in the fields of human motion detection and human–machine interfaces. Herein, TPU electrospun film sensors decorated with branch/rod-shaped PAN-based carbon nanofibers and carbon black via ultrasonication were fabricated successfully. The branch/rod-shaped carbon nanofibers were manufactured via electrospinning, carbonization, and subsequent ultrasonication. The best mass fraction ratio of carbon black to branch/rod-shaped carbon nanofibers was determined. Experiments to compare the mechanical and electrical properties and sensing performances of composite films decorated with branch/rod-shaped carbon nanofibers were conducted. Because the branch-shaped carbon nanofibers possess extra branches, the composite film decorated with branch-shaped carbon nanofibers and carbon black at the optimal mass fraction ratio exhibits higher performance than the sensor with rod-shaped carbon nanofibers; the film sensor can not only detect small strain of 0.1%, but it also shows good linearity in the range of 0.1–20% and a large strain-sensing maximum of 1000%. In addition, the fast response time (67 ms) and remarkable long-term durability (continuous stretching time of 7500 s) indicate that the as-designed film sensor is capable of the real-time detection of human motion. Finally, human–machine interaction testing was performed. The test results shows that our sensor can control the motion of a manipulator due to its excellent sensing performance. Overall, such a flexible film strain sensor can improve the development of wearable human-motion-detecting equipment and human–machine interfaces.