Interface-Enhanced Spherical TENG Sensors Based on PVDF and CNT Sponge for Assisted Driving Monitoring

To enhance motion monitoring and braking distance estimation capabilities for automotive assisted driving systems, this study presents a novel spherical triboelectric nanogenerator (S-TENG) sensor with directional detection capacity. The key innovation lies in integrating material self-forming surface micropores with a carbon nanotube sponge, which creates an enhanced triboelectric interface that significantly optimizes contact dynamics. This unique configuration increases the effective contact area by more than 98.6% and enables detection of subtle motion signals with superior force sensitivity (100.00 kPa^-1). A major scientific contribution of this work is establishing comprehensive correlations between output signals and critical parameters, including acceleration (0.2-4.1 m/s²), load (75-500 Pa), and directional vectors. Furthermore, we develop a groundbreaking self-sensing approach by continuously monitoring the peak open-circuit voltage (V_OC) and incorporating the braking distance factor L to establish a self-sensing equation for the friction coefficient based on the time integral of V_OC, which represents a significant advancement in self-powered sensing for intelligent transportation. The sensor achieves an acceleration sensitivity of 7.03 V/(m/s²), demonstrating its capability to provide multidirectional motion data. This study not only provides a viable strategy to enhance assisted driving safety but also advances the field of self-powered sensing technologies through its innovative design and analytical framework.