Hierarchical nanofibrous mat via water-assisted electrospinning for self-powered ultrasensitive vibration sensors

Triboelectric nanogenerators (TENGs) have emerged as portable and self-powered sensors owing to its effective energy harvesting capability and rapid electrical responsive signals. Enlarging the contact area is an efficient way for improving output performance of TENGs. Nevertheless, few effective ways to fabricate high roughness nanofibrous mat have been reported. Herein, we report a facile and controllable water-assisted electrospinning approach to fabricate hierarchical morphology mats (HMMs) for self-powered sensor application. Driven by Marangoni flow, the electrospun nanofibers always move toward the center of existing nanofiber net on still water surface and pushing the net contract, the mat is thus formed toward the bottom and grow continuously. By changing the parameters of electrospinning processing, the forming and growth of HMM were tuned successfully, the surface patterning was realized through a designed drying process. The prepared HMM holds good mechanical property and high roughness. Single-electrode TENG (H-S-TENG) was then assembled by using HMMs, and it exhibits high output performance and good stability. On the basis of H-S-TENG, the developed self-powered ultrasensitive vibration sensor (SUVS) achieves precise detection of pulse waves from different arteries, and realizes the identification of recorded vibration spectrum from different strings of a guitar. This study provides a promising approach to fabricate electrospinning nanofibrous mat with tuned surface microstructure for high performance self-powered sensors.