Flexible pyramidal BiFeO 3 –BaTiO 3 microcone arrays integrated with P(VDF-TrFE) for self-powered mechanical sensing and energy harvesting

Abstract

Flexible piezoelectric composites hold great promise for self-powered sensors and wearable electronics, but their performance is often limited by the low piezoelectricity of polymers, uneven dispersion of inorganic fillers, and poor interfacial stress transfer. To overcome these challenges, we fabricated a vertically oriented pyramidal BiFeO3-BaTiO3 (BFO-BTO) microcone array on P(VDF-TrFE) films using an AAO template-assisted method. The conical geometry induces localized stress concentration at the interface, thereby amplifying the local strain and enhancing the electromechanical response. Systematic studies reveal that microcone height critically influences the polarization behavior, piezoelectric coefficients, and overall device output. The resulting flexible devices, fabricated from the 1.5 μm BFO-BTO microcone/P(VDF-TrFE) composite piezoelectric films, achieve an open-circuit voltage of 5.12 V, a force sensitivity of 6.28 V·N-1 (linearity R2 = 0.98), while maintaining stable performance over 3000 mechanical cycles at 5 Hz under 0.66 N, demonstrating excellent durability. Moreover, the sensors enable high-precision, real-time monitoring of physiological and motion signals, including finger tapping, fist impacts, and foot stepping, highlighting their potential in intelligent health monitoring, human-machine interaction, and mechanical energy harvesting. This work elucidates how microcone structure design governs the electromechanical properties of flexible piezoelectric composites and offers practical design guidelines for flexible sensing and energy-harvesting applications.