Article
Nanoscience & Nanotechnology
Juan C. Marin Angel, Thein Kyu
Summary: The aim of this article is to develop flexoelectric polyelectrolyte elastomers for energy harvesting. The IL-grafted triblock copolymer network exhibits high ionic conductivity and ion polarization, leading to high flexoelectric coefficients during mechanical deformation. The addition of lithium salt further improves the flexoelectric coefficient, presenting new opportunities for clean energy harvesting from a vibrating natural environment.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Thermodynamics
Shengkai Su, Huaiwei Huang, Zheng H. Zhu
Summary: A flexoelectric energy harvester based on controllable wrinkling mechanism is proposed in this paper to enhance energy harvesting efficiency, utilizing an electrode-regrouping technique for optimization. The power density of these energy harvesters is at least 1 orders of magnitude higher than vibrational energy harvesters at the micro-scale, and the energy density can exceed 104W=m(3) at scales below 100 nm, significantly outperforming other types of vibrational energy harvesters.
Article
Chemistry, Physical
Yida Yang, Laurent Hirsinger, Michel Devel
Summary: Flexoelectricity is an electromechanical coupling phenomenon that can generate electric polarization in dielectric materials for nanoscale strain gradients. This study focuses on calculating the flexoelectric coefficients of 2D-MoS2 using a model with self-consistently determined charges and dipoles on the atoms. The importance of previously neglected contributions, such as the charge term in total polarization and the conservation of electric charge through a Lagrange multiplier, is investigated. The results show that the improved definition of polarization yields flexoelectric coefficients that agree better with experimental measurements when consistent sign definitions are used.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Energy & Fuels
E. F. Rojas, S. Faroughi, A. Abdelkefi, Y. H. Park
Summary: A reduced-order model considering material structure, size dependency, and surface smoothness effects was developed to study the performance of piezoelectric and/or flexoelectric systems at different scale levels. The study showed that at nanoscale, the combined piezoelectric and flexoelectric configuration and the flexoelectric only configuration perform similarly, but at transition scales, from nano to micro, the combined system outperforms either configuration. A non-smooth surface was found to increase the harvested power levels of the system in all cases, indicating that a piezoelectric-flexoelectric system can generate more power than previously thought near the microscale.
Article
Mathematics, Interdisciplinary Applications
Xing Chen, Song Yao, Julien Yvonnet
Summary: A numerical procedure based on isogeometric analysis is developed to analyze the dynamic response of flexoelectric systems in the frequency domain. The potential of IGA in modeling complex geometries and its sensitivity to different parameters are investigated. The results show that dynamic loads can induce larger flexoelectric effects and be used in energy harvesters.
COMPUTATIONAL MECHANICS
(2023)
Article
Nanoscience & Nanotechnology
Yanlong Xia, Yun Ji, Yuan Liu, Li Wu, Ya Yang
Summary: The rapid development of the automotive and aerospace industries has created a growing demand for electromechanical coupling materials and devices. This study demonstrates the tunable piezo-flexoelectric effect in ferroelectric Ba0.7Sr0.3TiO3 materials, providing a convenient route for scavenging and sensing vibration energy.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Xiaoying Zhuang, Tran Quoc Thai, Timon Rabczuk
Summary: Recent advances in nanotechnology have enabled the manufacturing of nanostructures and nanodevices with optimized topologies that outperform traditional counterparts in terms of efficiency and function. This study presents a novel nonlinear topology optimization procedure for designing optimal layouts of flexoelectric structures undergoing large displacement. The optimal material distribution is determined by optimizing energy conversion efficiency using a penalization approach and energy interpolation scheme. The results highlight the importance of accounting for geometric nonlinearity and size effects in characterizing and designing micro-structures and flexoelectricity.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2023)
Article
Physics, Applied
Shuwen Zhang, Chongpu Zhai, Kaiyuan Liu, Siyang Song, Hui Ji, Shubao Shao, Minglong Xu
Summary: Piezoelectric and flexoelectric materials have been increasingly studied for mechanical energy harvesting due to their simplicity, accessibility, compatibility, and efficiency in electro-mechanical conversion. This work proposes a coefficient m to quantitatively evaluate the energy harvesting capability of different types of materials and elucidates the underlying mechanism for their energy conversion capabilities.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Qing Ma, Huaiwei Huang, Yajun Cao
Summary: The flexoelectric effect at the micro/nanoscale can enhance energy harvesting performance, making it more suitable than piezoelectric energy harvesters. This study investigates the energy harvesting characteristics of micro circular plates with variable material properties and considers the flexoelectric effect through theoretical modeling and numerical simulations. The results show that the size effect and radial gradient distributions significantly influence frequency response and energy conversion efficiency, with the proposed model achieving a greatly improved maximum power density compared to homogeneous flexoelectric structures.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Physics, Applied
S. Baroudi, H. Samaali, F. Najar
Summary: The nonlinear vibration problem of a clamped-clamped monolithic piezoelectric flexoelectric beam as an energy harvester was investigated. The structure was found to be capable of harvesting energy, with the generated energy mainly attributed to the longitudinal potential variation and the transverse piezoelectric coefficient.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Engineering, Environmental
Hao Wang, Zhicheng Li, Songhan Shi, Xu Fan, Zhigang Sun, Jinjun Liu, Peng Li, Jiwei Zhai, Zhongbin Pan
Summary: This study proposes a new method to improve the output performance of piezoelectric energy harvesters by constructing heterostructure nanofibers, enhancing the synergistic effect of piezoelectricity and flexoelectricity. The best sample exhibits excellent output voltage and current, showing great potential in self-power applications.
CHEMICAL ENGINEERING JOURNAL
(2023)
Review
Engineering, Electrical & Electronic
Alekhika Tripathy, Balasubramaniam Saravanakumar, Smita Mohanty, Sanjay K. Nayak, Ananthakumar Ramadoss
Summary: This review summarizes the flexoelectric effects in different dielectric materials and their characterization methods, while discussing the use of different mechanical structures to measure electric outputs corresponding to different components of strain gradient. It also explores recent theoretical models and factors influencing the flexoelectric response, along with potential applications and energy harvesting techniques. Furthermore, it touches upon recent advancements and applications of flexoelectricity, as well as its potential impact on the development of nanoelectronics.
ACS APPLIED ELECTRONIC MATERIALS
(2021)
Article
Energy & Fuels
Joshua D. Wilbur, Chris Dames
Summary: Traditional pyroelectric energy conversion research has focused on improving energy output per cycle, but this study analyzes power output optimization for pyroelectric energy harvesting systems. The study highlights the importance of the average temperature amplitude of the pyroelectric material compared to the available thermal resource. By considering different types of thermal energy sources, figures of merit are identified to improve power harvesting performance within different frequency regimes.
Article
Chemistry, Physical
Baoran Shi, Qiman Wang, Hao Su, Junlong Li, Biao Xie, Pengpeng Wang, Jiawen Qiu, Chaoxing Wu, Yongai Zhang, Xiongtu Zhou, Tae Whan Kim
Summary: This paper provides a detailed overview of the structural design, performance improvements, and power management circuit applications of triboelectric nanogenerators (TENGs) for harvesting wind energy. It also summarizes the areas of application and future directions for TENGs in wind energy harvesting.
Article
Materials Science, Multidisciplinary
Hui Ji, Shubao Shao, Kaiyuan Liu, Tonghui Wu, Shengping Shen, Shuwen Zhang, Minglong Xu
Summary: This study presents a mechanical design approach to enhance flexoelectricity by creating an elastic modulus gradient, and combining material design with non-uniform geometric shape, resulting in a significant improvement of the flexoelectric effect.
MECHANICS OF MATERIALS
(2022)
Article
Physics, Applied
Ahmed Allam, Karim Sabra, Alper Erturk
Summary: The study demonstrates the enhancement of sound energy harvesting by focusing acoustic waves using a 3D-printed gradient-index phononic crystal lens. Numerical simulations and experimental validations show excellent agreement, with the lens significantly increasing the intensity of sound energy and enabling micro-Watt level power output. This technology has potential applications for wireless sensors and other low-power electronic components.
APPLIED PHYSICS LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Mohid Muneeb Khattak, Christopher Sugino, Alper Erturk
Summary: This study investigates piezoelectric energy harvesting on a locally resonant metamaterial beam for concurrent power generation and bandgap formation. Numerical and experimental analysis shows that most of the vibrational energy is localized near the excited base of the beam, and the majority of the total harvested power is extracted by the first few resonators.
JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES
(2022)
Article
Engineering, Mechanical
Hamed Farokhi, Yiwei Xia, Alper Erturk
Summary: This study experimentally investigates the nonlinear dynamics of cantilevers under base excitation to validate a geometrically exact model. Thorough comparisons between experimental and theoretical results demonstrate excellent agreement in both relatively large and extremely large oscillation amplitudes.
NONLINEAR DYNAMICS
(2022)
Article
Physics, Applied
Mustafa Alshaqaq, Christopher Sugino, Alper Erturk
Summary: In this study, we investigated spatially programmable rainbow trapping and band gap enhancement using a graded piezoelectric metamaterial beam and synthetic impedance circuits. We found that by adjusting the resonant frequency of each unit cell, we could achieve spatial wave trapping and enhance the attenuation bandwidth. The experiments confirmed the feasibility and effectiveness of this design.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Applied
Christopher Sugino, Romain Gerbe, Ehren Baca, Charles Reinke, Massimo Ruzzene, Alper Erturk, Ihab El-kady
Summary: This study investigates the use of elastic waves and ultrasonic transducers to communicate and supply power through metallic barriers. Machined periodic grooves alter the guided wave propagation within the barrier, greatly reducing signal crosstalk voltage.
APPLIED PHYSICS LETTERS
(2022)
Article
Mechanics
Oluwafemi Ojo, Yu-Cheng Wang, Alper Erturk, Kourosh Shoele
Summary: The fluttering response of heavy inverted flags with different aspect ratios is studied to understand how vortical structures influence the intermittent vibration response of the flag. Experimental and numerical results show that there is significant hysteretic bistability between different oscillatory modes, which is caused by the distinct roles of vortices around the flag. The interaction between the flexible plate and the vortices is quantified and it is found that the aspect ratio can significantly alter the hysteresis behavior and bistable response of the flag.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Physics, Applied
Jonatha Santini, Christopher Sugino, Emanuele Riva, Alper Erturk
Summary: Rainbow trapping is a phenomenon that confines vibrations by gradually varying the wave velocity in space using locally resonant unit cells. This strategy is employed in electromechanical metastructures to improve energy conversion and maximize power harvesting. A hybrid configuration is investigated, leveraging the synergistic interplay between mechanical and electromechanical resonators. Numerical results demonstrate enhanced energy harvesting and wideband vibration attenuation capabilities of the hybrid metastructure, compared to previous efforts.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Instruments & Instrumentation
Ahmed Allam, Karim Sabra, Alper Erturk
Summary: This study achieves simultaneous power harvesting and backscatter communication through frequency multiplexing. A high sensitivity and high bandwidth piezoelectric transducer is designed and a technique to separate power and data into different frequency bands is developed. These technologies can extend the range and bandwidth of ultrasonically powered devices.
SMART MATERIALS AND STRUCTURES
(2022)
Article
Instruments & Instrumentation
Obaidullah Alfahmi, Christopher Sugino, Alper Erturk
Summary: Piezoelectric shunt damping techniques using linear and switching circuits have been well studied for suppressing resonant vibrations. This work introduces cubic inductance to emulate nonlinearity and demonstrates precise digital programming and tuning capability. Experimental and simulation results validate the effectiveness of this approach.
SMART MATERIALS AND STRUCTURES
(2022)
Article
Engineering, Multidisciplinary
Oluwafemi Ojo, Eetu Kohtanen, Aojia Jiang, Jacob Brody, Alper Erturk, Kourosh Shoele
Summary: This study numerically investigates the flow-structural interaction of a 2D inverted flag behind a cylindrical bluff body, simulating a leaf behind a tree branch. The study reveals different fluttering modes of the flag under different distances and flow velocities.
BIOINSPIRATION & BIOMIMETICS
(2022)
Article
Automation & Control Systems
Ahmed Allam, Christian Arrington, Christopher St John, Jef Steinfeldt, Alper Erturk, Ihab El-Kady
Summary: In this study, ultrasonic power transfer through metallic barriers was investigated using experiments, analytical modeling, and numerical simulations. A Class E amplifier design was integrated with the ultrasonic system, achieving 83% ac-to-ac efficiency through a 3 mm aluminum barrier at 1 MHz. The system's overall dc-to-dc efficiency peaked at 68% while delivering 17.5 W to a dc load.
IEEE-ASME TRANSACTIONS ON MECHATRONICS
(2023)
Article
Physics, Applied
Renan L. Thomes, Danilo Beli, Christopher Sugino, Alper Erturk, Carlos De Marqui Junior
Summary: In this work, the concept of space-time wave localization is experimentally demonstrated using programmable defects. The dynamic properties of local resonators in an electromechanical metamaterial are controlled digitally to modulate a trivial point defect in space and time. The results show gradual transfer and localization of vibration energy over subsequent unit cells based on the defect position. The practical realization of space-time wave localization using programmable defects in elastic metamaterials may enable innovative solutions for information transmission, multiplexing and demultiplexing, sensing, and coding.
PHYSICAL REVIEW APPLIED
(2023)
Article
Engineering, Mechanical
Hamed Farokhi, Eetu Kohtanen, Alper Erturk
Summary: In this study, the extreme parametric resonance responses of flexible cantilevered beams are captured through experimental measurements and compared to a geometrically exact beam model. The experimental setup includes a vacuum chamber, a shaker and a high-speed camera to capture the deformed configurations of the cantilever. The results show that the model predictions are in excellent agreement with the experimental results at various oscillation amplitudes.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Instruments & Instrumentation
Alan Luo, Boris Lossouarn, Alper Erturk
Summary: This paper investigates the damping of multimodal vibrations in a thin circular ring using a piezoelectric electrical network. The electrical network, derived from a finite difference model and electromechanical analogy, exhibits properties analogous to the dynamics of a curved beam. Numerical simulations demonstrate the effectiveness of the network in attenuating vibrations across a wide frequency spectrum. The novelty of this research lies in the experimental validation of curved beam analogues and the exploration of coupling between a circular ring and its piezoelectric electrical network counterpart.
SMART MATERIALS AND STRUCTURES
(2023)
Article
Materials Science, Multidisciplinary
Christopher Sugino, Mustafa Alshaqaq, Alper Erturk
Summary: We have demonstrated high-precision dispersion tailoring in a metamaterial waveguide, allowing for wave compression and spatially tunable signal amplification. The refractive index is controlled using digital controllers connected to piezoelectric unit cells, enabling arbitrary programming of the waveguide's refractive index. Optimization techniques were used to implement gradual wave compression in the waveguide, resulting in increased sensitivity and amplification of piezoelectric voltage output.