Barium Titanate Film Interfaces for Hybrid Composite Energy Harvesters

We establish and analyze an analytical framework by accounting for both the piezoelectric and flexoelectric effects in bimorph cantilevers. The focus is placed on the development of governing electroelastodynamic piezoelectric–flexoelectric equations for the problems of resonant energy harvesting, sensing, and actuation. The coupled governing equations are analyzed to obtain closed-form frequency response expressions via modal analysis. The combined piezoelectric–flexoelectric coupling coefficient expression is identified and its size dependence is explored. Specifically, a typical atomistic value of the flexoelectric constant for barium titanate is employed in the model simulations along with its piezoelectric constant from the existing literature. It is shown that the effective electromechanical coupling of a piezoelectric material, such as barium titanate, is significantly enhanced for thickness levels below 100 nm. The electromechanical coupling coefficient of a barium titanate bimorph cantilever increases from the bulk piezoelectric value of 0.065 to the combined piezoelectric–flexoelectric value exceeding 0.3 toward nanometer thickness level. Electromechanical frequency response functions for resonant power generation and dynamic actuation also capture the size-dependent enhancement of the electromechanical coupling. The analytical framework given here can be used for parameter identification and design of nanoscale cantilevers that can be used as energy harvesters, sensors, and actuators.

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Printed Nanocomposite Energy Harvesters with Controlled Alignment of Barium Titanate Nanowires

ACS Applied Materials & Interfaces ◽

10.1021/acsami.8b13643 ◽

2018 ◽

Vol 10 (44) ◽

pp. 38359-38367 ◽

Cited By ~ 11

Author(s):

Mohammad H. Malakooti ◽

Florian Julé ◽

Henry A. Sodano

Keyword(s):

Barium Titanate ◽

Energy Harvesters ◽

Titanate Nanowires

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Ultra-Long Barium Titanate Nanowire Arrays for Low Frequency Energy Harvesting Applications

Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation and Control of Adaptive Systems; Structural Health Monitoring; Keynote Presentation ◽

10.1115/smasis2014-7426 ◽

2014 ◽

Author(s):

Aneesh Koka ◽

Henry A. Sodano

Keyword(s):

Barium Titanate ◽

Energy Harvesting ◽

Resonant Frequency ◽

Vibrational Energy ◽

Low Frequency ◽

Piezoelectric Response ◽

Synthesis Process ◽

Mechanical Vibrations ◽

Energy Harvesters ◽

Vertically Aligned

Piezoelectric nanowires (NWs) have recently attracted immense interest due to their excellent electro-mechanical coupling behavior that can efficiently enable conversion of low-intensity mechanical vibrations for powering or augmenting batteries of biomedical devices and portable consumer electronics. Specifically, nano-electromechanical systems (NEMS) composed of piezoelectric NWs offer an exciting potential for energy harvesting applications due to their enhanced flexibility, light weight, and compact size. Compared to the bulk form, high aspect ratio NWs can exhibit higher deformation to produce an enhanced piezoelectric response at a lower stress level. NEMS made of conventional semiconducting vertically aligned, ZnO NW arrays have been investigated thoroughly for energy harvesting; however, ZnO has a lower piezoelectric coupling coefficient as compared to many ferroelectric ceramics which limits its piezoelectric performance. Amidst lead-free ferroelectric materials, environmentally-friendly barium titanate (BaTiO3) possesses one of the highest piezoelectric strain coefficients and thus can enable greater energy transfer when used in vibrational energy harvesters. In this paper, a novel NEMS energy harvester is fabricated using ultra-long (∼40 μm long), vertically aligned BaTiO3 NW arrays which has a low resonant frequency (below 200 Hz) and its AC power harvesting capacity from low amplitude base vibrations (0.25 g) is demonstrated. The design and fabrication of low resonant frequency vibrational energy harvesters has been challenging in the field of MEMS/NEMS since the high stiffness of the structures results in resonant frequency often greater than 1 kHz. However, ambient mechanical vibrations usually exist in the 1 Hz to 1 kHz range and thus highly complaint ultra-long, NW arrays are beneficial to enable efficient energy conversion. Through the use of this newly developed synthesis process for the growth of highly compliant, ultra-long BaTiO3 NW arrays, it is shown that piezoelectric NWs based NEMS energy harvesters capable of harnessing this low frequency ambient vibrational energy can be conceived.

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