Electromechanical modeling and experimental verification of a direct write nanocomposite

Abstract

Piezoelectric materials are currently among the most promising building blocks for sensing, actuation and energy harvesting systems. However, these materials are limited in certain applications due to their lack of machinability as well as their inability to conform to curved surfaces. One method to mitigate this issue is through additive manufacturing (direct printing) of piezoelectric nanocomposites, where piezoelectric nanomaterials are embedded in a polymer matrix. Although significant progress has been made in this area, filler morphology, alignment and volume fraction are critical parameters that influence the electromechanical response and have not been adequately modeled. With the advent of additive manufacturing it is now possible to realize directly printed nanocomposites with tailored microstructure. The objective of this study is to develop and experimentally validate micromechanical and finite element models that allow the study of the electroelastic properties of a directly printed nanocomposite containing piezoelectric inclusions. Furthermore, the dependence of these properties on geometrical parameters such as aspect ratio and alignment of the active phase are investigated. In particular, the core focus of this work is to demonstrate how the gradual alignment of piezoelectric nanowires in the nanocomposite from randomly oriented to purely aligned can improve electroelastic properties of a printed nanocomposite. Finally, this work provides the first experimental validation of the theoretical and FEM models through measurement of the electroelastic properties of the nanocomposites containing barium titanate nanowires in a polydimethylsiloxane (PDMS) polymer matrix.

Nanomaterial Patterning in 3D Printing

“…Due to the crystallographic structure of piezoelectric crystals, the magnitude of the electrical response is dependent on the direction of applied stress 197. Nafari and Sodano used DIW to produce a piezoelectric composite made of shear‐aligned barium titanate nanowires suspended in polydimethylsiloxane (PDMS) 198. An electromechanical model and experimental verification demonstrated that aligning the nanowires longitudinally with the applied stress can increase the electromechanical coupling up to 90% that of pure lead zirconate titanate (PZT‐7A) 199.…”

Piezoelectric Fibers: Processing and Challenges

“…In addition to the difficulties of poling, mechanical stress transfer between the soft matrix and the stiff inorganic inclusions is another critical issue. Using high-aspect-ratio piezoelectric fillers and aligning them improves the mechanical coupling of the composite and results in higher piezoelectric response. − Andrew et al improved by more than 200% the d 33 of 20%vol PZT/PVDF composite films by using nanowires instead of quasi-spherical particles. This effect can be understood by considering the more efficient stress transfer in nanocomposites with high aspect ratio anisotropic nanoparticles .…”

“…183 Alignment of anisotropic particles is also important to ensure an efficient stress transfer, and a greater piezoelectric response with the polar axis of the nanoparticles along the axis of piezoelectric activity. Nafari and Sodano 179 demonstrated that a composite made of 40 wt % BaTiO 3 aligned nanowires with an aspect ratio of 10 in PDMS film has its d 33 coefficient enhanced by 100% compare with randomly oriented nanowires.…”

A Multiphysics Modeling of Electromagnetic Signaling Phenomena at kHz-GHz Frequencies in Bacterial Biofilms

“…The more non-zero elements the vector Y contains, the stronger is synchronization among the cells at that frequency which is determined by the strength of κ ij /s i . For simple demonstration of the concept and capability of our proposed approach, we have generated 2000 nonintersecting nanofibrils using a packing algorithm [77]. The nanofibrils are generated such that they are all confined within a box with dimensions 8 × 8 × 4 µm 3 (∼0.3% volume fraction) to represent a biofilm sample.…”