Piezoelectric Conversion Research Articles

An Integrated Dual-Side Series/Parallel Piezoelectric Resonator-Based DC-DC Converter

An Integrated Dual-Side Series/Parallel Piezoelectric Resonator-Based DC-DC Converter

Oxygen-Doped 2D In2Se3 Nanosheets with Extended In-Plane Lattice Strain for Highly Efficient Piezoelectric Energy Harvesting.

With the emergence of electromechanical devices, considerable efforts have been devoted to improving the piezoelectricity of 2D materials. Herein, an anion-doping approach is proposed as an effective way to enhance the piezoelectricity of α-In2Se3 nanosheets, which has a rare asymmetric structure in both the in-plane and out-of-plane directions. As the O2 plasma treatment gradually substitutes selenium with oxygen, it changes the crystal structure, creating a larger lattice distortion and, thus, an extended dipole moment. Prior to the O2 treatment, the lattice extension is deliberately maximized in the lateral direction by imposing in situ tensile strain during the exfoliation process for preparing the nanosheets. Combining doping and strain engineering substantially enhances the piezoelectric coefficient and electromechanical energy conversion. As a result, the optimal harvester with a 0.9% in situ strain and 10 min plasma exposure achieves the highest piezoelectric energy harvesting values of ≈13.5 nA and ≈420 µW cm-2 under bending operation, outperforming all previously reported 2D materials. Theoretical estimation of the structural changes and polarization with gradual oxygen substitution supports the observed dependence of the electromechanical performance.

A Self-Sensing Synchronous Switch Circuit for Bidirectional Piezoelectric Energy Conversion

A Self-Sensing Synchronous Switch Circuit for Bidirectional Piezoelectric Energy Conversion

Piezoelectric-electromagnetic collaborative energy extraction circuit for wearable vibration energy harvester

A piezoelectric-electromagnetic collaborative energy extraction circuit (PEC-EC) is presented in this paper to extract low-frequency vibration energy from arm swinging for wearable devices. This circuit simultaneously harvests energy from both the piezoelectric transducer (PZT) and electromagnetic coil generator (ECG). When the piezoelectric output voltage reaches its peak, the peak detection circuit becomes conductive, and the energy of the piezoelectric material is extracted at this moment. At the same time, the PEC-EC circuit can also harvest electromagnetic energy. Especially, even at low electromagnetic voltage input, the electromagnetic voltage can be extracted through the designed switch. The experimental results show that the circuit starts up only when the input voltage reaches 0.5V. The electromagnetic energy conversion efficiency can reach 53 %, and the piezoelectric energy conversion efficiency can reach 56 %. The effectiveness of collaborative extraction was also verified through experimental validation.

Study of the Frequency Range of Operation of a Piezoelectric Converter Acousto-Optical Filter Using Electrical and Optical Methods

Study of the Frequency Range of Operation of a Piezoelectric Converter Acousto-Optical Filter Using Electrical and Optical Methods

Long-lifespan and sterilizable face masks leveraging the power of light and electricity

The rapidly evolving virus and worsening air pollution have created a huge demand for face masks. However, most commercial masks are limited in their ability of long-time filtering air particulates and killing pathogens. We here present a highly germicidal, self-charging, and long-lifespan mask based on the synergistic effect of light (photocatalysis of CuO-ZIF-8) and electricity (piezoelectricity of PVDF-TrFE). Specifically, we synthesize CuO-ZIF-8 nanomaterials that are 99.999 % bactericidal against E. coli and S. aureus in PBS buffer under 2 h of simulated solar irradiation. Air filters made of CuO-ZIF-8 nanocubes and PVDF-TrFE nanofibers possess a low pressure drop of 90 Pa and high filtration efficiency of 99.01 % for 0.3 µm particles thanks to the piezoelectric energy conversion from breathing to electric charge accumulation. The filtration efficiency keeps up to 94.2 % for an ultralong 30 h, 6–7 times longer than surgical masks. This work sheds new light on developing public protective materials featured with photocatalytic antibacterial and piezoelectric enhanced adsorption.

Analysis of the Methods for Realization of Low-Power Piezoelectric Energy Harvesting Circuits for Wearable Battery-Free Power Supply Devices

This paper presents a comprehensive review of the design and implementation methods of low-power piezoelectric energy harvesting circuits, which in the last few years have gained an extremely large range of applications like the power sources of wearable electronic devices, such as biometrical sensors. Before examining the electronic circuitries of the self-supplied power devices, an overview of the structure, equivalent electrical circuits, and basic parameters of the piezoelectric generators and MEMSs as energy harvesting elements is presented. The structure of energy storage elements (parallel-plate capacitors and thin-film supercapacitors), suitable for this type of application, is also presented. The description of these components from an electrical point of view allows them to be easily workable when connected to the various power conversion electronic circuits. Based on an overview of the structure and the principles of operation, as well as some analytical expressions for energy efficiency evaluation, a comprehensive comparative analysis is presented. Depending on the advantages and disadvantages of the known circuit configurations, the basic electrical and design parameters are systematized in tabular form. Practical realizations of piezoelectric power conversion circuits are also presented in graphic form, ensuring the optimal value of energy efficiency and compactness in the construction of the devices.

Biomimetic bone-periosteum scaffold for spatiotemporal regulated innervated bone regeneration and therapy of osteosarcoma

The complexity of repairing large segment defects and eradicating residual tumor cell puts the osteosarcoma clinical management challenging. Current biomaterial design often overlooks the crucial role of precisely regulating innervation in bone regeneration. Here, we develop a Germanium Selenium (GeSe) co-doped polylactic acid (PLA) nanofiber membrane-coated tricalcium phosphate bioceramic scaffold (TCP-PLA/GeSe) that mimics the bone-periosteum structure. This biomimetic scaffold offers a dual functionality, combining piezoelectric and photothermal conversion capabilities while remaining biodegradable. When subjected to ultrasound irradiation, the US-electric stimulation of TCP-PLA/GeSe enables spatiotemporal control of neurogenic differentiation. This feature supports early innervation during bone formation, promoting early neurogenic differentiation of Schwann cells (SCs) by increasing intracellular Ca2+ and subsequently activating the PI3K-Akt and Ras signaling pathways. The biomimetic scaffold also demonstrates exceptional osteogenic differentiation potential under ultrasound irradiation. In rabbit model of large segment bone defects, the TCP-PLA/GeSe demonstrates promoted osteogenesis and nerve fibre ingrowth. The combined attributes of high photothermal conversion capacity and the sustained release of anti-tumor selenium from the TCP-PLA/GeSe enable the synergistic eradication of osteosarcoma both in vitro and in vivo. This strategy provides new insights on designing advanced biomaterials of repairing large segment bone defect and osteosarcoma.

Plasma Profiling of LiNbO3 Film for the Formation of Piezoelectric Energy Converters

Plasma Profiling of LiNbO3 Film for the Formation of Piezoelectric Energy Converters

Bistable dual cantilever flutter for potential wind energy harvesting applications

This paper examines the potential of bistable dual cantilever flutter (DCF) for wind energy harvesting applications. Two cantilever beams were placed side by side and perpendicular to the direction of the wind flow to create a unique phenomenon known as the DCF. Similar pole magnets were then attached to the free end of each beam to establish a bistable condition. A theoretical model was presented and was shown to agree well with the experimental measurement. The mass of the magnets caused the frequency of the beams to drop by approximately 4.5 times compared to the monostable DCF. When the two beams were placed 21.0 mm apart, the bistable beams achieved a stable state at a critical flutter speed of 5.3 ms−1 and displayed significantly large, anti-phase oscillations that is approximately three times larger than the monostable DCF. Further increase in this distance showed a decreasing trend with the critical flutter speed, which opposes the expected trend of the monostable DCF. Due to the bistable effect, significant flutter amplitudes were also obtained during a backward sweep when the wind speeds were incrementally reduced from high to low, recording a 73.2 % increase in bandwidth for one of the tested cases. This suggests the possibility of an ultra-wide bandwidth energy harvester. Finally, it was shown that the piezoelectric conversion method is more favourable for the bistable DCF whereas electromagnetic induction is preferred for the monostable DCF.

Enhanced piezoelectric properties in low-temperature sintered Pb(Zr,Ti)O3-based ceramics via Yb2O3 doping

Pb(Mg[Formula: see text]W[Formula: see text])O3–Pb(Ni[Formula: see text]Nb[Formula: see text])O3–Pb(Zr[Formula: see text]Ti[Formula: see text])O3 (PNN–PMW–PZT) piezoceramics were sintered at a low temperature of 900∘C by the mixed metal oxide powder solid-state reaction route. CaCO3 and Li2CO3 as sintering aids and Yb2O3 as a dopant were added into the PNN–PMW–PZT ceramic system for low-temperature sintering and enhancement of electrical properties, respectively. The effects of different Yb2O3 doping amounts on the microstructure, dielectric, piezoelectric and ferroelectric properties of the samples were systematically investigated. The piezoceramics doped with 0.1[Formula: see text]mol% Yb2O3 have optimal electrical properties ([Formula: see text][Formula: see text]pC/N, [Formula: see text], [Formula: see text] (1[Formula: see text]kHz), [Formula: see text] (1[Formula: see text]kHz), and [Formula: see text]C). While the piezoceramics doped with 0.3[Formula: see text]mol% Yb2O3 have optimal energy conversion properties: the piezoelectric voltage coefficient [Formula: see text][Formula: see text]Vm/N and the effective piezoelectric energy conversion coefficient [Formula: see text][Formula: see text]m2/N.

Achievement of a giant electromechanical conversion coefficient in a molecule-based ferroelectric.

Molecule-based ferroelectrics are promising candidates for flexible self-powered power supplies (i.e., piezoelectric generators (PEGs)). Although the large electromechanical conversion coefficients (d 33 × g 33) of piezoelectrics are key to enhancing the performance of PEGs in their nonresonant states, it remains a great challenge to obtain molecule-based piezoelectrics with large d 33 × g 33. Here, we report a molecule-based ferroelectric [(CH3)3NCH2CH2Cl][GaBr4] (1) that exhibits the largest piezoelectric coefficient (∼454 pC N-1) and electromechanical conversion coefficient (4953.1 × 10-12 m2 N-1) among all known free-standing polycrystalline pellets. Notably, the PEG comprising 15 wt% 1 and polydimethylsiloxane (PDMS) achieves a power density of up to 120 μW cm-2, marking the highest reported power density for ferroelectric@PDMS PEGs to date.

Improved Energy Harvesting Ability of Single-Layer Binary Fiber Nanocomposite Membrane for Multifunctional Wearable Hybrid Piezoelectric and Triboelectric Nanogenerator and Self-Powered Sensors.

While wearable self-powered electronic devices have shown promising improvements, substantial challenges persist in enhancing their electrical output and structural performance. In this work, a working mechanism involving simultaneous piezoelectric and triboelectric conversion within a monolayer-structured membrane is proposed. Single-layer binary fiber nanocomposite membranes (SBFNMs) (PVDF/CNTX@PAN/CNTX, DPCPCX) with two distinct interpenetrating nanocomposite fibers were created through co-electrospinning, incorporating multiwalled carbon nanotubes (CNTs) into polyvinylidene fluoride (PVDF) and polyacrylonitrile (PAN), respectively. The resulting membrane demonstrated an exceptional synergistic effect of piezoelectricity and triboelectricity along with a high machine-to-electric conversion capability. The addition of CNTs increased the PVDF β-phase and the PAN planar zigzag conformation. As a result, the DPCPC0.5-SBFNMs-based piezoelectric nanogenerator exhibited excellent electrical output (187 V, 8.0 μA, and 1.52 W m-2), maintaining an exceptionally high level of output voltage compared with other piezoelectric nanogenerators. It successfully illuminated 50 commercial light-emitting diodes simultaneously. The output voltage of DPCPC0.5-SBFNMs was 5.1 and 4.6 times higher than that of PAN or PVDF single-fiber membranes, respectively. Furthermore, the peak voltage of DPCPC0.5-SBFNMs exceeded that of co-electrospinning PVDF/CNT1.0@PAN (DPCP1.0) and PVDF@PAN/CNT1.0 (DPPC1.0) by 20 and 10 V, respectively. The piezoelectric sensor made of DPCPC0.5-SBFNMs accurately sensed human movement, ranging from tiny to large, and demonstrated utility as an alarm in medical treatment, fire fighting, and monitoring. Endogenous triboelectricity is proposed in SBFNM piezoelectric materials, enhancing electromechanical conversion and electrical output capacity, thereby promising a wide application potential in self-powered wearable electronic devices.

Modeling of hysteretic response of porous piezo/ferroelectric ceramics

The hysteretic character of the electromechanic coupling in porous piezoeceramics is a fundamental issue to be investigated in order to design porous materials with enhanced functional responses and increased figure of merit. In the present work, the porosity-dependent evolution of polarization-field PE and strain-field sE hysteretic responses of porous ferro/piezoceramics are simulated by using the Jiles-Atherton model for switching, combined with Finite Element Analysis in order to determine the local electrical and mechanical responses and the effective dielectric and piezoelectric constants. By considering 2D arrays of porous structures, the local electric field, potential and strain–stress local distributions are firstly evaluated in discrete elements. The macroscopic polarization and deformation responses vs. the applied field are determined by computing the response of each dense region subjected to its corresponding local field. The obtained nonlinear decrease of polarization and deformation vs. porosity are comparatively discussed for square, hexagonal regular pore arrays and for randomly distributed porosity. Further, the effective permittivity and piezoelectric constant d33 and conversion figure of merit vs. porosity computed in different polarization states are estimated and discussed. The present approach may offer a support for the design of porous structures with enhanced piezoelectric response.

Nonlinear-optical piezoelectric electrospun nanofibers

This paper presents a nonlinear optical piezoelectric electrospun nanocomposite of polyvinylidene fluoride (PVDF) nanofibers with embedded nanomaterial of poly {1-[p-(3’-carboxy-4’- hydroxyphenylazo) benzenesulfonamido]-1, 2-ethandiyl} (PCBS). PCBS of different weight ratios are added in-situ to the synthesized PVDF nanofibers. The generated nanofibers mats have been proved to possess both properties of piezoelectric response and nonlinear optical conversion due to the presence of both PVDF and PCBS, respectively. Innovatively, embedding PCBS within the PVDF nanofibers increases the piezoelectric response of the nanocomposite, compared to the case of neat PVDF nanofibers, at certain optimum weight concentrations of PCBS. This has been proved by different piezoelectric measurements at different applied forces and vibration frequencies, along with d33 coefficient measurements and supported by FTIR analysis of beta-sheets. Our results support the evidence of the coupling between the polarized diploes of PCBS and PVDF, which can enhance the overall piezoelectric response. Furthermore, the synthesized nanocomposite shows an optical second harmonic generation (SHG) at optimum concentration of added PCBS within the PVDF nanofibers of around 1 wt.%. The synthesized nonlinear optical nanocomposite of PVDF/PCBS can be multi-functionalized sensors/transducer membranes for biomedical and sensing applications.

Near Spurious-Free Thickness Shear Mode Lithium Niobate Resonator for Piezoelectric Power Conversion.

Piezoelectric power converters, where acoustic resonators replace the inductors as energy storage elements, promise much higher power density and higher efficiency compared to conventional circuits. Recently, lithium niobate (LiNbO3) piezoelectric resonators have been integrated within power converter circuits, showing good conversion efficiency, thanks to their high quality factor (Q) and electromechanical coupling (kt2). However, the converter output power range is limited by large spurious modes near resonance. This work reports a near-spurious-free LiNbO3 thickness shear (TS) resonator, demonstrating high Q of 3500 and kt2 of 45% at 5.94 MHz, with a fractional suppressed region of 35%. First, we identify the best LiNbO3 crystal orientation for efficient TS resonators. Then, we propose a novel acoustic design without busbars for spurious suppression, which is extensively simulated, fabricated, and characterized. Further analysis is done to identify existing spurious modes in our proposed design, specifically the effect of dicing on our TS resonator design. Upon optimization, LiNbO3 TS resonators could potentially empower a new design space for low-loss and compact power converters.

Design optimization of a submerged piezoelectric wave energy converter device using an artificial neural network model

The design of a submerged piezoelectric wave energy converter (PWEC) device has been analyzed to optimize the power generated (Pext) by the PWEC device. An artificial neural network (ANN) is adopted to optimize the geometric parameters of the device. First, a numerical model is introduced using the boundary element methodology (BEM). The input database for the modeling of the ANN model is generated using the Latin Hypercube Sampling (LHS) method, and the output database for the modeling of the ANN model is simulated using the numerical model based on BEM. Four hundred samples are used to model the ANN with data taken in a 70:30 ratio for training and validation of the model. The prediction of the optimal parameter values for the design of the PWEC device is carried out using a database containing 3000 sample points generated randomly using the LHS method. The developed ANN model shows a good agreement between the training accuracy and the validation accuracy. Also, the model forecast provides a range for the geometric parameters of the PWEC device to optimize Pext.

Precise Design of Molecular Ferroelectrics with High TC and Tunable Band Gap by Molecular Modification.

Molecular ferroelectric materials are widely applied in piezoelectric converters, non-volatile memorizers, and photovoltaic devices due to their advantages of adjustable structure, lightweight, easy processing, and environmental friendliness. However, designing multifunctional molecular ferroelectrics with excellent properties has always been a great challenge. Herein, a multiaxial molecular ferroelectric is successfully designed by modifying the quasi-spherical cation dabco with CuBr2 to obtain halogenated [Bretdabco]CuBr4 (Bretdabco = N-bromoethyl-N'-diazabicyclo [2.2.2]octane), which crystallizes in polar point groups (C6). Typical ferroelectric behaviors featured by the P-E hysteresis loop and switched ferroelectric domain are exhibited. Notably, the molecular ferroelectric shows a high TC of 460 K, which is rare in the field and could greatly expand the application range of this material. In addition, the band gap is adjustable through the regulation of halogen. Both the UV absorption spectra and theoretical calculations indicate that the molecular ferroelectrics belong to a direct band gap (2.14 eV) semiconductor. This tunable and narrow band gap semiconductor molecular ferroelectric material with high TC can be utilized more effectively in the study of optoelectronics and sensors, including piezoelectric energy harvesters. This research may provide a promising approach for the development of multiaxial molecular ferroelectrics with a tiny band gap and high TC.

Plucking and linear-to-rotary hybrid harvester for low-amplitude vibrations of high-speed railway with an innovative three-step amplification mechanism

By harvesting the pervasive vibration energy, self-powered wireless sensor network (WSN) installed along the track can play an important role in structure health monitoring of high-speed railway. However, a considerable part of vibration energy of the rail is difficult to be harvested due to the characteristics of ultra-low frequency, small amplitude and large load. A hybrid frequency up-conversion energy harvester is designed and optimized in this paper aiming to address this critical problem. By utilization of a unique three-step amplification design for reducing inefficient transmission due to the possible gap of gear or ball-screw systems, high-efficient energy harvesting is realized for the small-amplitude excitation with both electromagnetic and piezoelectric conversion structures. The experiment results verify that the gapless amplification achieved by the flexible hinge structure as the first-step mechanism is effective for solving the gap issue. Compared with harvesters without the flexible hinges, the power is 250% higher under an excitation of low frequency (5 Hz) and ultra-small amplitude (0.3 mm). Moreover, based on the hybrid energy harvesting mechanism, more appreciable energy is obtained by introducing the plucking piezoelectric structure in addition to the electromagnetic unit.

Broadband omnidirectional piezoelectric–electromagnetic hybrid energy harvester for self-charged environmental and biometric sensing from human motion

Vibration induced by human motions features a wide frequency spectrum and spatiotemporal-variable directions. Yet, it is challenging to concurrently expand frequency bandwidth and achieve multidirectional capability for effectively human-induced biomechanical energy harvesting and biometrics sensing. In this paper, we report a piezoelectric–electromagnetic hybrid energy harvester with coupled vibrational stabilization and induced frequency-up rotational mechanisms for omnidirectional and broadband vibration energy harvesting. Experimental studies demonstrate the proposed hybrid energy harvester operates effectively over a wide excitation frequency range from 6.0 to 16.0 Hz with omnidirectional responses. The piezoelectric conversion unit can provide a maximum output power of 0.9 mW and the electromagnetic conversion unit’s maximum output power is 22.7 mW. The hybrid energy harvester satisfies the power requirements of different types of portable electronics and realizes various self-charged sensing electronics that are stimulated by human movement. Various types of human motion signals are detected by piezoelectric and electromagnetic units via machine learning techniques to realize self-powered motion monitoring. Compared with a single type of signal, the identification accuracy of the hybrid device is improved from 85.6% to 100%. The proposed energy harvester for self-powered sensing paves the way to green intelligent life such as health management, environmental monitoring and human-machine interaction.