Anisotropic alignment of piezoelectric nanomaterials for enhancing polarization and sensing application

Abstract

Piezoelectric nanomaterials, which can convert mechanical stimuli into electrical signals, find applications in sensors and energy harvesting devices. The growing demand for enhancing the mechanical resilience and adaptability of piezoelectric nanomaterials when mounting them onto unstructured objects, piezoelectric nanomaterials have been incorporated into viscoelastic polymers to form composites. While piezoelectric composites offer a promising approach to fulfill such requirements, their potential generation is lower than that of individual piezoelectric nanomaterials. This is attributed to the random distribution of piezoelectric nanomaterials within the polymer matrix, leading to a reduction in net polarization. Additionally, the polymer matrix absorbs a portion of the stress that should be applied to the piezoelectric nanomaterials. In this work, we effectively aligned piezoelectric nanorods decorated with magnetic nanoparticles using external magnetic fields in an anisotropic configuration. Through this in-situ alignment technique within the polymer matrix, axially aligned nanorods demonstrated a significant increase in output voltage when exposed to external stress applied in alignment with the direction of the nanorods. This selective enhancement of the net polarization allows the use of piezoelectric nanocomposites in sensors capable of distinguishing different types of forces. In addition, the aligned nanorods maximize polarization in a specific direction while requiring a lower filler content compared to randomly distributed nanofillers in composites. This novel alignment method offers the prospect of highly flexible and lightweight piezoelectric sensors suitable for a wide range of applications, including wearables, healthcare systems, and self-powered devices.