The Influence of Shape on the Output Potential of ZnO Nanostructures: Sensitivity to Parallel versus Perpendicular Forces

Abstract

With the consistent shrinking of devices, micro-systems are, nowadays, widely used in areas such as biomedics, electronics, automobiles, and measurement devices. As devices shrunk, so too did their energy consumptions, opening the way for the use of nanogenerators (NGs) as power sources. In particular, to harvest energy from an object’s motion (mechanical vibrations, torsional forces, or pressure), present NGs are mainly composed of piezoelectric materials in which, upon an applied compressive or strain force, an electrical field is produced that can be used to power a device. The focus of this work is to simulate the piezoelectric effect in different ZnO nanostructures to optimize the output potential generated by a nanodevice. In these simulations, cylindrical nanowires, nanomushrooms, and nanotrees were created, and the influence of the nanostructures’ shape on the output potential was studied as a function of applied parallel and perpendicular forces. The obtained results demonstrated that the output potential is linearly proportional to the applied force and that perpendicular forces are more efficient in all structures. However, nanotrees were found to have an increased sensitivity to parallel applied forces, which resulted in a large enhancement of the output efficiency. These results could then open a new path to increase the efficiency of piezoelectric nanogenerators.

Coupled Electro-mechanical Behavior of Microtubules

“…In the present computational study, the coupled electro-mechanical model of a microtubule has been modelled by adopting a similar mathematical framework utilized for modeling zinc oxide (ZnO) nanowires [19][20]. Further, the numerical model fidelity and integrity have been evaluated by comparing the predicted results of the current model to those available in the literature, for e.g.…”

“…In this table, the maximum predicted electric potential and the displacement have been summarized for a different combination of forces. The value of maximum electric potential has been presented in absolute values [20], so as to better compare the electroelastic response of microtubule under different forces. As evident from Table 2, the application of 0.1 nN shear force results in the generation of bigger displacements and corresponding electric potential within the microtubule when compared to a perpendicular compressive force.…”

“…The modelling parameters considered in the present computational study are given in Table 1 [16][17][18]. The constitutive equations for a linearly coupled electro-mechanical model are given by [19][20][21][22]:…”

Addendum: Cardoso, J., et al. The Influence of Shape on the Output Potential of ZnO Nanostructures: Sensitivity to Parallel versus Perpendicular Forces. Nanomaterials 2018, 8, 354

“…The authors wish to add the following information to the acknowledgements section of their paper published in Nanomaterials [ 1 ].…”

1D Nanostructure-Based Piezo-Generators

“…The authors evidence a correlation between the enhancement of the piezoelectric response of the nanofibers and their degree of alignment. In a second paper, J. Cardoso et al [10] simulate the influence of various ZnO NW shapes (NWs under the brunched, non-branched and nanomushroom form) on their output potential as a function of the applied force direction. Important relations between form, geometric parameters, and output voltage were extracted.…”