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23 pages, 4058 KiB

Open AccessArticle

Optimized Design of a Self-Biased Amplifier for Seizure Detection Supplied by Piezoelectric Nanogenerator: Metaheuristic Algorithms versus ANN-Assisted Goal Attainment Method

by Swagata Devi, Koushik Guha, Olga Jakšić, Krishna Lal Baishnab and Zoran Jakšić

Micromachines 2022, 13(7), 1104; https://doi.org/10.3390/mi13071104 - 14 Jul 2022

Cited by 1 | Viewed by 2012

Abstract

This work is dedicated to parameter optimization for a self-biased amplifier to be used in preamplifiers for the diagnosis of seizures in neuro-diseases such as epilepsy. For the sake of maximum compactness, which is obligatory for all implantable devices, power is to be [...] Read more.

This work is dedicated to parameter optimization for a self-biased amplifier to be used in preamplifiers for the diagnosis of seizures in neuro-diseases such as epilepsy. For the sake of maximum compactness, which is obligatory for all implantable devices, power is to be supplied by a piezoelectric nanogenerator (PENG). Several meta-heuristic optimization algorithms and an ANN (artificial neural network)-assisted goal attainment method were applied to the circuit, aiming to provide us with the set of optimal design parameters which ensure the minimal overall area of the preamplifier. These parameters are the slew rate, load capacitor, gain–bandwidth product, maximal input voltage, minimal input voltage, input voltage, reference voltage, and dissipation power. The results are re-evaluated and compared in the Cadence 180 nm SCL environment. It has been observed that, among the metaheuristic algorithms, the whale optimization technique reached the best values at low computational cost, decreased complexity, and the highest convergence speed. However, all metaheuristic algorithms were outperformed by the ANN-assisted goal attainment method, which produced a roughly 50% smaller overall area of the preamplifier. All the techniques described here are applicable to the design and optimization of wearable or implantable circuits. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Analysis, Design and Fabrication)

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16 pages, 7502 KiB

Open AccessArticle

Theoretical and Experimental Investigation of a Rotational Magnetic Couple Piezoelectric Energy Harvester

by Feng Sun, Runhong Dong, Ran Zhou, Fangchao Xu and Xutao Mei

Micromachines 2022, 13(6), 936; https://doi.org/10.3390/mi13060936 - 12 Jun 2022

Cited by 10 | Viewed by 2215

Abstract

With the rapid development of Internet of Things (IoT) and the popularity of wireless sensors, using internal permanent or rechargeable batteries as a power source will face a higher maintenance workload. Therefore, self-powered wireless sensors through environmental energy harvesting are becoming an important [...] Read more.

With the rapid development of Internet of Things (IoT) and the popularity of wireless sensors, using internal permanent or rechargeable batteries as a power source will face a higher maintenance workload. Therefore, self-powered wireless sensors through environmental energy harvesting are becoming an important development trend. Among the many studies of energy harvesting, the research on rotational energy harvesting still has many shortcomings, such as rarely working effectively under low-frequency rotational motion or working in a narrow frequency band. In this article, a rotational magnetic couple piezoelectric energy harvester is proposed. Under the low-frequency excitation (<10 Hz) condition, the harvester can convert low-frequency rotational into high-frequency vibrational of the piezoelectric beam by frequency up-conversion, effectively increasing the working bandwidth (0.5–16 Hz) and improving the efficiency of low-speed rotational energy harvesting. In addition, when the excitation frequency is too high (>16 Hz), it can solve the condition that the piezoelectric beam cannot respond in time by frequency down-conversion. Therefore, the energy harvester still has a certain degree of energy harvesting ability (18–22 Hz and 29–31 Hz) under high-frequency conditions. Meanwhile, corresponding theoretical analyses and experimental verifications were carried out to investigate the dynamic characteristics of the harvester with different excitation and installation directions. The experimental results illustrate that the proposed energy harvester has a wider working bandwidth benefiting from the frequency up-conversion mechanism and frequency down-conversion mechanism. In addition, the forward beam will have a wider bandwidth than the inverse beam due to the softening effect. In addition, the maximum powers of the forward and inverse beams at 310 rpm (15.5 Hz) are 93.8 μW and 58.5 μW, respectively. The maximum powers of the two beams at 420 rpm (21 Hz) reached 177 μW and 85.2 μW, respectively. The self-powered requirement of micromechanical systems can be achieved. Furthermore, this study provides the theoretical and experimental basis for rotational energy harvesting. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Analysis, Design and Fabrication)

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11 pages, 2774 KiB

Open AccessArticle

Vibration Energy Harvesting from the Subwavelength Interface State of a Topological Metamaterial Beam

by Yongling Lu, Zhen Wang, Xueqiong Zhu, Chengbo Hu, Jinggang Yang and Yipeng Wu

Micromachines 2022, 13(6), 862; https://doi.org/10.3390/mi13060862 - 30 May 2022

Cited by 6 | Viewed by 2075

Abstract

Topological metamaterial has been a research hotpot in both physics and engineering due to its unique ability of wave manipulation. The topological interface state, which can efficiently and robustly centralize the elastic wave energy, is promising to attain high-performance energy harvesting. Since most [...] Read more.

Topological metamaterial has been a research hotpot in both physics and engineering due to its unique ability of wave manipulation. The topological interface state, which can efficiently and robustly centralize the elastic wave energy, is promising to attain high-performance energy harvesting. Since most of environmental vibration energy is in low frequency range, the interface state is required to be designed at subwavelength range. To this end, this paper developed a topological metamaterial beam with local resonators and studied its energy-harvesting performance. First, the unit cell of this topological metamaterial beam consists of a host beam with two pairs of parasitic beams with tip mass. Then, the band structure and topological features are determined. It is revealed that by tuning the distance between these two pairs of parasitic beams, band inversion where topological features inverse can be obtained. Then, two sub-chains, their design based on two topologically distinct unit cells, are assembled together with a piezoelectric transducer placed at the conjunction, yielding the locally resonant, topological, metamaterial, beam-based piezoelectric energy harvester. After that, its transmittance property and output power were obtained by using the frequency domain analysis of COMSOL Multiphysics. It is clear that the subwavelength interface state is obtained at the band-folding bandgap. Meanwhile, in the interface state, elastic wave energy is successfully centralized at the conjunction. From the response distribution, it is found that the maximum response takes place on the parasitic beam rather than the host beam. Therefore, the piezoelectric transducer is recommended to be placed on the parasitic beam rather than host beam. Finally, the robustness of the topological interface state and its potential advantages on energy harvesting were studied by introducing a local defect. It is clear that in the interface state, the maximum response is always located at the conjunction regardless of the defect degree and location. In other words, the piezoelectric transducer placed at the conjunction can maintain a stable and high-efficiency output power in the interface state, which makes the whole system very reliable in practical implementation. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Analysis, Design and Fabrication)

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16 pages, 9432 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

A Magnetically Coupled Piezoelectric–Electromagnetic Low-Frequency Multidirection Hybrid Energy Harvester

by Yongqiang Zhu, Zhaoyang Zhang, Pingxia Zhang and Yurong Tan

Micromachines 2022, 13(5), 761; https://doi.org/10.3390/mi13050761 - 11 May 2022

Cited by 16 | Viewed by 5050

Abstract

The traditional single electromechanical conversion energy harvester can collect energy only in a single vibration direction. Moreover, it requires high environmental vibration frequency, and its output power is low. To solve these problems, a cross-shaped magnetically coupled piezoelectric–electromagnetic hybrid harvester is proposed. The [...] Read more.

The traditional single electromechanical conversion energy harvester can collect energy only in a single vibration direction. Moreover, it requires high environmental vibration frequency, and its output power is low. To solve these problems, a cross-shaped magnetically coupled piezoelectric–electromagnetic hybrid harvester is proposed. The harvester comprised a ring-shaped support frame, a piezoelectric generation structure, and an electromagnetic generation structure. The harvester could simultaneously generate energy piezoelectrically and electrically, in addition, it could generate electricity efficiently at a lower environmental vibration, and it can collect the energy in two vibration directions simultaneously. To verify the effectiveness of the device, we set up a vibration experiment system and conducted comparative experiments about non-magnetically coupled piezoelectric, magnetically coupled piezoelectric, and magnetically coupled piezoelectric–electromagnetic hybrid energy harvesters. The experimental results showed that the output power of the magnetically coupled piezoelectric–electromagnetic hybrid energy harvester was 2.13 mW for the piezoelectric structure and 1.76 mW for the electromagnetic structure under the vibration of single-direction resonant frequency. The total hybrid output power was 3.89 mW. The hybrid harvester could collect vibration energy parallel to the ring in any direction. Furthermore, compared with the non-magnetically coupled piezoelectric energy harvester and the magnetically coupled piezoelectric energy harvester, the output power was increased by 141.6% and 55.6%, respectively. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Analysis, Design and Fabrication)

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14 pages, 5203 KiB

Open AccessArticle

Design and Comparative Study of a Small-Stroke Energy Harvesting Floor Based on a Multi-Layer Piezoelectric Beam Structure

by Xiang Zhong, Hengyang Wang, Lin Chen and Mingjie Guan

Micromachines 2022, 13(5), 736; https://doi.org/10.3390/mi13050736 - 3 May 2022

Cited by 2 | Viewed by 2257

Abstract

Recently, research on the energy harvesting floor is attracting more and more attention due to its possible application in the smart house, invasion monitoring, internet of things, etc. This paper introduced a design and comparative study of a small-stroke piezoelectric energy harvesting floor [...] Read more.

Recently, research on the energy harvesting floor is attracting more and more attention due to its possible application in the smart house, invasion monitoring, internet of things, etc. This paper introduced a design and comparative study of a small-stroke piezoelectric energy harvesting floor based on a multi-layer piezoelectric beam structure. The multi-layer piezoelectric beams are designed based on simply supported beams in an interdigitated manner. Theoretical analysis is explored to find out the beam number and layer number of the structure. Through this design, the input power from the human footsteps was effectively utilized and transformed into electrical power. The designed piezoelectric energy harvesting floor structure was tested by our designed stepping machine, which can simulate the stepping effect of a walking human on the floor with different parameters such as stepping frequency. Comparative studies of the energy harvester are carried out regarding different stepping frequencies, external circuits, and initial beam shapes. The experimental results showed that the maximum output power of a group of four-layer prototypes was 960.9 µW at a stroke of 4 mm and a step frequency of 0.83 Hz, with the beams connected in parallel. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Analysis, Design and Fabrication)

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16 pages, 16151 KiB

Open AccessArticle

A Funnel Type PVDF Underwater Energy Harvester with Spiral Structure Mounted on the Harvester Support

by Jongkil Lee, Jinhyo Ahn, Hyundu Jin, Chong Hyun Lee, Yoonsang Jeong, Kibae Lee, Hee-Seon Seo and Yohan Cho

Micromachines 2022, 13(4), 579; https://doi.org/10.3390/mi13040579 - 7 Apr 2022

Cited by 6 | Viewed by 2065

Abstract

For the purpose of stably supplying electric power to the underwater wireless sensor, the energy harvesting technology in which a voltage is obtained by generating displacement in a piezoelectric material using flow-induced vibration is one of the most attractive research fields. The funnel [...] Read more.

For the purpose of stably supplying electric power to the underwater wireless sensor, the energy harvesting technology in which a voltage is obtained by generating displacement in a piezoelectric material using flow-induced vibration is one of the most attractive research fields. The funnel type energy harvester (FTEH) with PVDF proposed in this study is an energy harvester in which the inlet has a larger cross-sectional area than the outlet and a spiral structure is inserted to generate a vortex flow at the inlet. Based on numerical analysis, when PVDF with L = 100 mm and t = 1 mm was used, the electric power of 39 μW was generated at flow velocity of 0.25 m/s. In experiment the average RMS voltage of FTEH increased by 0.0209 V when the flow velocity increased by 1 m/s. When measured at 0.25 m/s flow velocity for 25 s, it was shown that voltage doubler rectifier (VDR) generated a voltage of 133.4 mV, 2.25 times larger than that of full bridge rectifier (FBR), and the energy charged in the capacitor was 44.3 nJ, 14% higher in VDR than that of the FBR. In addition, the VDR can deliver power of 17.75 μW for 1 k

Ω

load. It is shown that if the voltage generated by the FTEH using the flow velocity is stored using the VDR electric circuit, it will greatly contribute to the stable power supply of the underwater wireless sensor. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Analysis, Design and Fabrication)

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15 pages, 4253 KiB

Open AccessArticle

Self-Adaptive Pendulum-Ball Switches for Piezoelectric Synchronous-Extraction Circuits

by Yao Huang, Gang Qin and Weiqun Liu

Micromachines 2022, 13(4), 532; https://doi.org/10.3390/mi13040532 - 28 Mar 2022

Cited by 1 | Viewed by 1874

Abstract

Electronic synchronous switches are usually used to enhance the performance of piezoelectric energy-extraction circuits, but the electronic components leading to additional power consumption are not desired for energy extraction. In view of the advantage of mechanical switches without power consumption, this article proposed [...] Read more.

Electronic synchronous switches are usually used to enhance the performance of piezoelectric energy-extraction circuits, but the electronic components leading to additional power consumption are not desired for energy extraction. In view of the advantage of mechanical switches without power consumption, this article proposed a synchronous-switch circuit which can adapt to the amplitude of a cantilever-beam-vibration generator with less energy loss. This mechanical switch consists of two pendulum balls and two buffer springs. This switch mechanism can automatically adapt to the cantilever-displacement amplitude, control the closing and opening of switches with the decrease in phase advance angle, and increase in energy-extraction efficiency. Different from previous adaptive mechanical switches, this unique pendulum-ball mechanism can not only reduce the weight and volume of the generator to improve the energy density, but can also simply adjust the pendulum length to achieve better harvesting performance. It is verified experimentally that the adaptive mechanical switch can close and open automatically under different cantilever amplitudes and excitation frequencies; the results show that the optimal power of the proposed circuit can reach 4.2 times that of the standard circuit. In order to further optimize the adaptive mechanical switch, the parameters of the swing-ball mechanism affecting harvesting performance is analyzed. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Analysis, Design and Fabrication)

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15 pages, 8003 KiB

Open AccessArticle

Multimodal Multidirectional Piezoelectric Vibration Energy Harvester by U-Shaped Structure with Cross-Connected Beams

by Hongbo Qin, Shuting Mo, Xin Jiang, Siyao Shang, Peng Wang and Yan Liu

Micromachines 2022, 13(3), 396; https://doi.org/10.3390/mi13030396 - 28 Feb 2022

Cited by 10 | Viewed by 2697

Abstract

This paper proposes a multidirectional piezoelectric vibration energy harvester based on an improved U-shaped structure with cross-connected beams. Benefitting from the bi-directional capacity of U-shaped beam and additional bending mode induced by cross-connected configuration, the proposed structure can well capture the vibrations in [...] Read more.

This paper proposes a multidirectional piezoelectric vibration energy harvester based on an improved U-shaped structure with cross-connected beams. Benefitting from the bi-directional capacity of U-shaped beam and additional bending mode induced by cross-connected configuration, the proposed structure can well capture the vibrations in 3D space at the frequencies lower than 15 Hz. These features are further validated by finite element analyses and theorical formulas. The prototype is fabricated and the experiments under different conditions are carried out. The results show that the proposed harvester can generate favorable voltage and power under multidirectional vibrations at a low operating frequency. Practical applications of charging capacitors and powering a wireless sensor node demonstrate the feasibility of this energy harvester in supplying power for engineering devices. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Analysis, Design and Fabrication)

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10 pages, 1641 KiB

Open AccessArticle

Design and Experimental Investigation of a Rotational Piezoelectric Energy Harvester with an Offset Distance from the Rotation Center

by Jun Chen, Xiangfu Liu, Hengyang Wang, Sheng Wang and Mingjie Guan

Micromachines 2022, 13(3), 388; https://doi.org/10.3390/mi13030388 - 28 Feb 2022

Cited by 9 | Viewed by 3109

Abstract

Rotational energy harvesting technology has attracted more and more attention recently. This paper presents a piezoelectric rotational energy harvester that can be mounted with an offset distance from the rotation center. The piezoelectric energy harvester is designed to be dynamically excited by the [...] Read more.

Rotational energy harvesting technology has attracted more and more attention recently. This paper presents a piezoelectric rotational energy harvester that can be mounted with an offset distance from the rotation center. The piezoelectric energy harvester is designed to be dynamically excited by the force due to gravity, which causes the piezoelectric cantilever beams in the harvester to vibrate periodically as the harvester rotates. A novel design of the harvester structure with a hollow mass is proposed and analyzed in this paper. Experiments were performed to investigate the design and analysis. A power output of 106~2308 μW can be achieved at the rotating frequencies of 0.79~14 Hz with a piezoelectric cantilever beam in the prototyped energy harvester. Results showed that the prototyped harvester can be mounted on a rotating wheel hub and output sufficient power in a wide frequency range for wireless monitoring sensors. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Analysis, Design and Fabrication)

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17 pages, 6421 KiB

Open AccessArticle

Analysis of Preload of Three-Stator Ultrasonic Motor

by Zheng Li, Hui Zhao, Shuai Che, Xuetong Chen and Hexu Sun

Micromachines 2022, 13(1), 5; https://doi.org/10.3390/mi13010005 - 22 Dec 2021

Cited by 7 | Viewed by 2733

Abstract

The pre-pressure device of the ultrasonic motor plays a vital role in the design of the entire motor structure, the contact state of the stator and rotor of the motor, dynamic properties of the stator, friction and wear characteristics of the rotor; even [...] Read more.

The pre-pressure device of the ultrasonic motor plays a vital role in the design of the entire motor structure, the contact state of the stator and rotor of the motor, dynamic properties of the stator, friction and wear characteristics of the rotor; even the mechanical behaviors of the entire electric machinery have a profound impact. Appropriate pre-pressure is conducive to the smooth operation of the ultrasonic motor, so that the output performance remains excellent, reducing wear and effectively extend the service life of the motor. Therefore, the research on pre-stress is of great significance, as it can better optimize the structure of the three-stator ultrasonic motor and lay the foundation for the stable operation of the motor. First, this paper introduces the construction of the motor as a whole and the pre-pressure device briefly described the working mechanism of the motor, and then introduces the influence of the pre-pressure on the stator and rotor contact models, the position of the constant velocity point, and the modal frequency. Finally, the motor output under different pre-pressures is discussed. The performance experiment has determined the optimal pre-pressure interval, which provides help for its subsequent optimization. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Analysis, Design and Fabrication)

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10 pages, 6249 KiB

Open AccessArticle

Design, Manufacture and Test of Piezoelectric Cantilever-Beam Energy Harvesters with Hollow Structures

by Baozhi Wang, Chenggong Zhang, Liyan Lai, Xuan Dong and Yigui Li

Micromachines 2021, 12(9), 1090; https://doi.org/10.3390/mi12091090 - 10 Sep 2021

Cited by 3 | Viewed by 4994

Abstract

This article presents a single-crystal piezoelectric energy harvester (PEH) with a trapezoidal hollow hole that can obtain high energy density at low frequency. Harvesters with a hollow structure were fabricated through a series of manufacturing processes such as thermocompression bonding, screen printing and [...] Read more.

This article presents a single-crystal piezoelectric energy harvester (PEH) with a trapezoidal hollow hole that can obtain high energy density at low frequency. Harvesters with a hollow structure were fabricated through a series of manufacturing processes such as thermocompression bonding, screen printing and laser cutting. Finite element analysis (FEA) and experimental results showed that using low modulus brass instead of stainless steel as the PEH substrate enhances the voltage output of the device, and the hollow design greatly increases the overall stress level and power density. In addition, the developed PEH with a trapezoidal hole obtained the best output performance; when the acceleration, resonance frequency and matched load resistance were 0.5 g, 56.3 Hz and 114 kΩ, respectively, the peak voltage was 17 V and the power density was 2.52 mW/cm³. Meanwhile, compared with the unhollowed device, the peak voltage and maximum power density of the proposed PEH were increased by 30.7% and 24.4%, respectively, and the resonance frequency was reduced by 7%. This study verified the feasibility of the optimized design through simulation and experimental comparison. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Analysis, Design and Fabrication)

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Review

Jump to: Research

20 pages, 4817 KiB

Open AccessReview

Circuit Techniques for High Efficiency Piezoelectric Energy Harvesting

by Yi Yang, Zhiyuan Chen, Qin Kuai, Junrui Liang, Jingjing Liu and Xiaoyang Zeng

Micromachines 2022, 13(7), 1044; https://doi.org/10.3390/mi13071044 - 30 Jun 2022

Cited by 5 | Viewed by 4661

Abstract

This brief presents a tutorial on multifaceted techniques for high efficiency piezoelectric energy harvesting. For the purpose of helping design piezoelectric energy harvesting system according to different application scenarios, we summarize and discuss the recent design trends and challenges. We divide the design [...] Read more.

This brief presents a tutorial on multifaceted techniques for high efficiency piezoelectric energy harvesting. For the purpose of helping design piezoelectric energy harvesting system according to different application scenarios, we summarize and discuss the recent design trends and challenges. We divide the design focus into the following three categories, namely, (1) AC-DC rectifiers, (2) C_P compensation circuits, (3) maximum power point tracking (MPPT) circuits. The features, problems encountered, and suitable systems of various AC-DC rectifier topologies are introduced and compared. The important role of non-linear methods for piezoelectric energy harvesting is illustrated from the perspective of impedance matching. Energy extraction techniques and voltage flipping techniques based on inductors, capacitors, and hybrid structures are analyzed. MPPT techniques with different features and targets are discussed. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Analysis, Design and Fabrication)

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15 pages, 4655 KiB

Open AccessReview

Three Frequency Up-Converting Piezoelectric Energy Harvesters Caused by Internal Resonance Mechanism: A Narrative Review

by Jian Liu, Yongling Lu, Zhen Wang, Sen Li and Yipeng Wu

Micromachines 2022, 13(2), 210; https://doi.org/10.3390/mi13020210 - 28 Jan 2022

Cited by 12 | Viewed by 2862

Abstract

Low frequency mechanical vibrations are ubiquitous in practical environments, and how to efficiently harvest them with piezoelectric materials remains a challenge. Frequency up-conversion strategies—up-converting low frequency vibrations to high frequency self-oscillations—can improve the power density of piezoelectric materials. This paper mainly introduces a [...] Read more.

Low frequency mechanical vibrations are ubiquitous in practical environments, and how to efficiently harvest them with piezoelectric materials remains a challenge. Frequency up-conversion strategies—up-converting low frequency vibrations to high frequency self-oscillations—can improve the power density of piezoelectric materials. This paper mainly introduces a kind of frequency which up-converts piezoelectric energy harvesters based on an internal resonance mechanism, compared with the other mechanisms caused by mechanical impact, mechanical plucking, etc.; the internal resonance-based harvesters can up-convert the frequency under a condition of lower excitation level, less energy loss, and less wideband operation bandwidth. Benefits to practical vibrations also exist in these multi-degree-of-freedom nonlinear dynamic systems. Moreover, the value of the frequency up-conversion factor based on the 1:2:6 internal resonance mechanism can reach as much as six so far, which is also a quite a high frequency up-conversion value. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Analysis, Design and Fabrication)

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