High-sensitivity and self-powered flexible pressure sensor based on multi-scale structured piezoelectric composite

High-sensitivity piezoelectric sensors exhibit immense application potential in flexible electronics. This work proposes a novel multi-scale architectural engineering strategy to dramatically enhance the piezoelectric performance of P(VDF-TrFE) based piezoelectric sensors through a single-step electrohydrodynamic (EHD) pulling process. In microscopic scale, this method effectively facilitates the fabrication of vertically arranged P(VDF-TrFE) based nanocomposite micropillar array structures. In nanoscopic scale, the incorporated nanofillers are simultaneously oriented along the longitudinal axis of micropillar during the EHD pulling process. The micro- and nano-level design significantly enhances piezoelectric output performance of the sensor. The results indicate that the voltage output signals of the structured P(VDF-TrFE)/CNTs@Al₂O₃ and P(VDF-TrFE)/boron nitride nanotubes (BNNTs) composites sensors are 159-fold and 89-fold higher than that of pure P(VDF-TrFE) flat film-based sensors, respectively. Particularly, the optimized P(VDF-TrFE)/CNTs@Al₂O₃ composite sensor exhibits an ultrahigh sensitivity of 527.64 mV·kPa⁻¹ and an ultra-low pressure detection limit of ~3.5 Pa. The enhancement mechanisms of high performance are mainly attributed to dual-scale structural design. The micropillar structures, due to the strain confinement effect, enables micropillar to bear a greater load and generate higher output. The aligned nanofillers further enhance the efficiency of force transfer, while also optimizing dielectric loss, charge transfer, and polarization efficiency. Finally, the sensor demonstrated exceptional performance in detecting “vascular pulsations” under subtle pressure. Overall, the synergistic effect significantly enhanced piezoelectricity of the nanocomposite materials, which can be achieved in a single EHD pulling process. This approach provides an effective strategy for designing high-performance flexible piezoelectric sensors.