Piezoelectric Mechanism Research Articles

Deciphering the piezoelectric and conductive mechanisms of Nb-doped Bi3Ti1.5W0.5O9 high-temperature piezoelectric ceramics

The study utilizes Bi3Ti(1.5-x)NbxW0.5O9 (BTW-xNb, x=0.00, 0.01, 0.02, 0.04, 0.06) bismuth layered piezoelectric ceramics synthesized via a conventional solid-phase reaction process. This is the study to investigate the impact of B-site Nb ion doping on the structural and electrical properties of BTW-xNb ceramic. The results show that all ceramics have a single bismuth layer structure, with reduced lattice distortion according to Rietveld refinement findings. The presence of oxygen vacancies in the ceramic is the main factor that affects the high temperature conductivity of the samples. The XPS results, the increase in the activation energy of AC and DC conductivity confirm that doping with Nb5+ ions reduces oxygen vacancy concentration. The ceramics with the highest overall electrical performance are the BTW-0.02 Nb ceramics. Notably, the DC resistivity at 500 °C was enhanced from 9.16 × 105 Ω·cm (x = 0.00) to 8.24 × 106 Ω·cm. The TC was enhanced from 730 °C(undoped) to 743 °C. At 500 °C, tanδ decreases from 21.1 % to 8.2 %. The ceramic's increased resistivity increases the polarization voltage, resulting in more complete polarization. The d33 is increased from 7.5 pC/N (undoped) to 13 pC/N. Furthermore, the piezoelectric properties remain stable up to 700°C, suggesting that the material has considerable potential for use at elevated temperatures.

Exploring the mechanisms of enhanced piezoelectric properties in (K,Na)NbO3 single crystals

(K,Na)NbO3 (KNN)-based piezoelectric materials are candidates for replacing Pb-based materials. However, the piezoelectric properties of existing KNN-based single crystals are still inferior to those of Pb-based relaxor ferroelectric single crystals. Moreover, the piezoelectric response mechanism of KNN-based single crystals remains unclear. In this study, (Li,K,Na)(Nb,Sb,Ta)O3:Mn (KNNLST:Mn) single crystals with an excellent piezoelectric coefficient d33 of approximately 778 pC/N were prepared. Systematically studies of intrinsic and extrinsic piezoelectric responses have revealed that the high d33 of KNNLST:Mn single crystals is related to the shear piezoelectric response of a single-domain state and irreversible domain wall motion of the engineering domains. Furthermore, the effect of the orthorhombic (O)-tetragonal (T) phase boundary on intrinsic and extrinsic piezoelectric response is systematically studied, and the impact mechanism is elucidated. The results indicate that a lower dielectric response and elastic constant limit the intrinsic shear piezoelectric response of KNNLST:Mn single crystals, and approaching the O–T phase boundary can enhance both intrinsic and extrinsic piezoelectric responses. This study improves our understanding of the structure-performance relationship in KNN-based single crystals and offers insights for optimizing piezoelectric properties in KNN-based materials.

One-step hydrothermal synthesis of ternary heterostructure stannic sulfide - bismuth sulfide - bismuth oxychloride (SnS2-Bi2S3-BiOCl) composite loaded on carbon felt for highly efficient piezocatalytic degradation of organic dyes and antibiotics

The piezoelectric catalysis technique harnesses naturally occurring vibrational energy to remove organic pollutants from water in an environmentally friendly manner. In this study, a ternary heterostructure SnS2-Bi2S3-BiOCl (S-B-B) composite was successfully synthesized via a one-step hydrothermal method and simultaneously deposited on the surface of carbon felt. The S-B-B heterojunction exhibits significantly enhanced piezoelectric catalytic activity compared to SnS2, Bi2S3, and BiOCl, achieving a k value of 2.26 × 10⁻² min⁻¹ and a degradation efficiency of 89.9 % towards methyl orange (MO) dye after 100 min of ultrasonic degradation. This performance is markedly superior to the individual components, with k values of 3.80 × 10⁻⁴ min⁻¹ for SnS2, 1.16 × 10⁻² min⁻¹ for BiOCl, and 1.31 × 10⁻² min⁻¹ for Bi2S3. Moreover, in addition to levofloxacin (LV), it demonstrates high removal efficiency for Congo red (CR), methylene blue (MB), tetracycline hydrochloride (TC-HCl), and sulfanilamide (SN). Furthermore, it can be loaded onto carbon felt for use in piezoelectric catalytic degradation of dyeing wastewater, highlighting its potential for practical applications. Trapping experiments suggest that singlet oxygen non-radicals and hydroxyl radicals play a critical role in the piezocatalytic degradation of organic contaminants. Based on LC-MS results, a possible degradation pathway for MO dye is proposed. Furthermore, DFT calculations confirm electron transfer from Bi2S3 to SnS2 and BiOCl at the interfaces between SnS2/Bi2S3 and BiOCl/Bi2S3. The piezoelectric mechanism of the S-B-B composite is also elucidated, highlighting the interaction and electron dynamics within the heterostructure.

Focus-Switchable Piezoelectric Actuator: A Bionic Thin-Plate Design Inspired by Conch Structure

Traditional camera zoom mechanisms, relying on stepper motors and intricate transmission components, suffer from bulky designs that restrict their applicability in compact systems. This study presents a novel piezoelectric focus-switchable mechanism (PFSM) directly driven by a biomimetic radial-mode piezoelectric actuator (RMPA) with inclined driving structure mimicking the conch shell. The PFSM utilizes rotational motion for optical zoom, providing a more compact and efficient alternative to conventional linear motion-based systems. By utilizing finite element method (FEM) optimization, we developed a compact prototype (34×34×3mm³, 14.83g) and experimentally verified its performance, achieving a peak rotational speed of 1573.14 RPM, torque output of 3.6 mN·m, and step displacement resolution of 45.8 μrad. These attributes enable smooth lens module switching for optical zoom, thus demonstrating the mechanism’s feasibility. Importantly, the PFSM offers precise positioning without relying on additional transmission parts and features a self-locking capability when de-energized, rendering it an ideal choice for camera zoom applications. In summary, this study underscores the PFSM’s potential as a compact, lightweight, and efficient camera zoom mechanism, contributing meaningfully to the field of imaging technology and optical systems.

Advanced Materials for Energy Harvesting and Soft Robotics: Emerging Frontiers to Enhance Piezoelectric Performance and Functionality.

Piezoelectric energy harvesting captures mechanical energy from a number of sources, such as vibrations, the movement of objects and bodies, impact events, and fluid flow to generate electric power. Such power can be employed to support wireless communication, electronic components, ocean monitoring, tissue engineering, and biomedical devices. A variety of self-powered piezoelectric sensors, transducers, and actuators have been produced for these applications, however approaches to enhance the piezoelectric properties of materials to increase device performance remain a challenging frontier of materials research. In this regard, the intrinsic polarization and properties of materials can be designed or deliberately engineered to enhance the piezo-generated power. This review provides insights into the mechanisms of piezoelectricity in advanced materials, including perovskites, active polymers, and natural biomaterials, with a focus on the chemical and physical strategies employed to enhance the piezo-response and facilitate their integration into complex electronic systems. Applications in energy harvesting and soft robotics are overviewed by highlighting the primary performance figures of merits, the actuation mechanisms, and relevant applications. Key breakthroughs and valuable strategies to further improve both materials and device performance are discussed, together with a critical assessment of the requirements of next-generation piezoelectric systems, and future scientific and technological solutions.

Highly aligned thin PVDF/Cloisite 30B nanofibers as a piezoelectric sensor

One-dimensional confined nanostructures with intense dipole orientation exhibit enhanced piezoelectric performance compared to traditional three-dimensional bulk films. Herein, we show that preparing highly aligned thin polyvinylidene fluoride (PVDF) nanofibers in the presence of a small amount of organically modified clay (Cloisite 30B) platelets induces a significant crystal polymorphism alteration from non-polar α-phase to polar β-phase rather than the randomly oriented neat PVDF nanofibers with a larger average diameter. It has been detected that the nanofiber orientation considerably contributes to the enhanced degree of crystallinity and mechanical properties. Also, the PVDF-Cloisite 30B interactions caused an improvement in the elastic modulus. The piezoelectric performance of the electrospun nanofibers was examined by sensing characteristics. It was found that the synergistic effects of nanofiber orientation and clay platelets efficiently improve sensing performance via the piezoelectric dipole orientation mechanism.

A tunable pendulum-like piezoelectric energy harvester for multidirectional vibration

Harvesting energy from vibrations using piezoelectric mechanism has attracted much attention for powering wireless sensors over the past decade. This paper proposes a tunable pendulum-like piezoelectric energy harvester for multidirectional vibration (TP-PVEH) to enhance the power generation characteristic, durability, and environmental adaptability of energy harvester. Unlike traditional cantilevered piezoelectric vibration energy harvesters (PVEHs), which typically lowered working frequencies by adding the weight of proof mass at the end of beam or reshaping beam, TP-PVEH employed a pendulum to harness low-frequency vibrations. Moreover, in contrast to typical pendulum-like PVEHs, the pendulum in this design was not mounted at the end of beam but was attached to a radial spherical plain bearing (RSPB) structure, which avoided the irreversible beam damage caused by gravitational force. TP-PVEH utilized simple-pendulum-induced RSPB motion to smoothly pluck piezoelectric beams, subjecting the piezoelectric beams to unidirectional compressive stress only. Meanwhile, the RSPB structure's capability to facilitate multidirectional rotation enabled TP-PVEH to efficiently capture energy from various directions. Theoretical analysis, numerical analysis and experiment tests were conducted to validate the design and examine how excitation and structural parameters influenced on the output performance of TP-PVEH. The results demonstrated that the excitation amplitude, excitation angle, proof mass, and mass distance brought significant effects on the output characteristic of TP-PVEH. The working frequency, output voltage and power could be efficiently tuned by the abovementioned parameters. With an excitation amplitude of 3 mm, TP-PVEH achieved an optimal output power of 9.81 mW and an output power density of 11.37 μW/mm3, operating with a load resistance of 200 kΩ at a frequency of 12.5 Hz.TP-PVEH could power 100 blue LEDs and a calculator. Additionally, the ability of TP-PVEH to charge capacitors further demonstrated its practical power supply capabilities.

Advances in Portable and Wearable Acoustic Sensing Devices for Human Health Monitoring.

The practice of auscultation, interpreting body sounds to assess organ health, has greatly benefited from technological advancements in sensing and electronics. The advent of portable and wearable acoustic sensing devices marks a significant milestone in telemedicine, home health, and clinical diagnostics. This review summarises the contemporary advancements in acoustic sensing devices, categorized based on varied sensing principles, including capacitive, piezoelectric, and triboelectric mechanisms. Some representative acoustic sensing devices are introduced from the perspective of portability and wearability. Additionally, the characteristics of sound signals from different human organs and practical applications of acoustic sensing devices are exemplified. Challenges and prospective trends in portable and wearable acoustic sensors are also discussed, providing insights into future research directions.

A Comprehensive Review of Strategies toward Efficient Flexible Piezoelectric Polymer Composites Based on BaTiO3 for Next-Generation Energy Harvesting

The increasing need for wearable and portable electronics and the necessity to provide a continuous power supply to these electronics have shifted the focus of scientists toward harvesting energy from ambient sources. Harvesting energy from ambient sources, including solar, wind, and mechanical energies, is a solution to meet rising energy demands. Furthermore, adopting lightweight power source technologies is becoming more decisive in choosing renewable energy technologies to power novel electronic devices. In this regard, piezoelectric nanogenerators (PENGs) based on polymer composites that can convert discrete and low-frequency irregular mechanical energy from their surrounding environment into electricity have attracted keen attention and made considerable progress. This review highlights the latest advancements in this technology. First, the working mechanism of piezoelectricity and the different piezoelectric materials will be detailed. In particular, the focus will be on polymer composites filled with lead-free BaTiO3 piezoceramics to provide environmentally friendly technology. The next section will discuss the strategies adopted to enhance the performance of BaTiO3-based polymer composites. Finally, the potential applications of the developed PENGs will be presented, and the novel trends in the direction of the improvement of PENGs will be detailed.

Extended electronegative-difference-ratio effect on the enhanced out-of-plane piezoelectricity in MXenes monolayers

2D MXenes materials with out-of-plane piezoelectricity are competitive in numerous cutting-edge applications. However, it is still challenging to find MXenes materials with high-performance out-of-plane piezoelectricity and further reveal the piezoelectric mechanism. Here, via first-principles calculations, six stable ScYCTT' (T, T' = F, Cl or Br; T ≠ T') semiconductors are identified from 24 kinds of MXenes compounds. These semiconductors exhibit excellent out-of-plane piezoelectricity, surpassing many reported MXenes piezoelectric materials. The functional-group-modification-model and extended electronegative-difference-ratio (redScYCTT′) in the five-atom-layer ScYCTT' monolayers are defined for the first time to understand the piezoelectric physical mechanism. We find that the larger redScYCTT′corresponds to the larger out-of-plane piezoelectricity within the same group, which is defined as the electronegative-difference-ratio effect. This effect is also proved by data from 17 kinds of materials in other works. This work provides new perspectives for understanding the out-of-plane piezoelectric mechanism and offers promising candidates for touch screens and biomimetic skin.

Molecular Mechanisms and Enhancement of Piezoelectricity in the M13 Virus

AbstractUnderstanding the structure and function of bioelectric materials is challenging due to the complex nature of biomaterials and a lack of appropriate tools. The precisely defined structures and genetic tunability of viruses provide an excellent model system to investigate bioelectrical behavior in biomaterials. This study presents the molecular mechanisms of piezoelectricity in the M13 bacteriophage (phage) under various mechanical stresses for bio‐piezoelectric generation. A computational approach is used to calculate the piezoelectric tensors of the M13 phage and quantify its direction‐dependent dipole moments. By computationally designing negatively charged residues on the phage surface, the surface charge density is enhanced to 16.7 µC cm−2. Using genetic engineering, phages are experimentally designed with different charges and tail structures to create model phage nanostructures, including individual phages, vertically standing phage films, and horizontally aligned phage films. Their vertical, horizontal, and shear‐mode piezoelectric properties are then measured using scanning probe microscopy techniques. The resulting phage‐based piezoelectric energy generators exhibit an effective piezoelectric coefficient of 15.4 pm V−1 and a power density of 4.2 µW cm−2. This phage‐based bioengineering approach provides a versatile platform for investigating fundamental mechanisms of bioelectricity and designing bioelectric materials for applications in energy harvesting, biomemory, and biosensors.

Advancements in Energy Harvesting: Piezoelectric, Triboelectric, Pyroelectric, and Magnetoelectric Technologies for Self-powered Sensor Systems

In the era of Internet of Things (IoT) advancements, millions of sensors and electronic devices are interconnected through the internet. A reliable power source is required for their continuous operation. Self-powered sensor systems have emerged as promising solutions for various applications including wearable devices and environmental monitoring, benefiting both society and the environment. These systems can maintain themselves by eliminating the need for external power sources or frequent battery replacements and converting discarded energy sources around them into electrical energy. Among various energy harvesting technologies, piezoelectric, triboelectric, pyroelectric, and magnetoelectric mechanisms have garnered significant attention due to their ability to convert mechanical, frictional, thermal, and magnetic energy into electrical power, respectively. This review aims to provide a comprehensive overview of recent advances in these technologies for self-powered sensor systems, catering to a wide audience. It explores fundamental principles of their-energy harvesting mechanisms, highlighting their strengths, limitations, and potential applications. In addition, this review discusses challenges related to the development of nanogenerator-based self-powered sensor systems and presents new opportunities for their advancement.

High-speed forward-viewing optical coherence tomography probe based on Lissajous sampling and sparse reconstruction.

We present a novel endoscopy probe using optical coherence tomography (OCT) that combines sparse Lissajous scanning and compressed sensing (CS) for faster data collection. This compact probe is only 4 mm in diameter and achieves a large field of view (FOV) of 2.25 mm2 and a 10 mm working distance. Unlike traditional OCT systems that use bulky raster scanning, our design features a dual-axis piezoelectric mechanism for efficient Lissajous pattern scanning. It employs compressive data reconstruction algorithms that minimize data collection requirements for efficient, high-speed imaging. This approach significantly enhances imaging speed by over 40%, substantially improving miniaturization and performance for endoscopic applications.

Application of catalytic technology based on the piezoelectric effect in wastewater purification

The demands of human life and industrial activities result in a significant influx of toxic contaminants into aquatic ecosystems. In particular, organic pollutants such as antibiotics and dye molecules, bacteria, and heavy metal ions are represented, posing a severe risk to the health and continued existence of living organisms. The method of removing pollutants from water bodies by utilizing the principle of the piezoelectric effect in combination with chemical catalytic processes is superior to other wastewater purification technologies because it can collect water energy, mechanical energy, etc. to achieve cleanliness and high removal efficiency. Herein, we briefly introduced the piezoelectric mechanisms and then reviewed the latest advances in the design and synthesis of piezoelectric materials, followed by a summary of applications based on the principle of piezoelectric effect to degrade pollutants in water for wastewater purification. Moreover, water purification technologies incorporating the piezoelectric effect, including piezoelectric effect-assisted membrane filtration, activation of persulfate, and battery electrocatalysis are elaborated. Finally, future challenges and research directions for the piezoelectric effect are proposed.

Dual-function of energy harvesting and vibration isolation via quasi-zero stiffness piezoelectric mechanism

Industry 4.0 realizes intelligent interconnection through the sensor group of the Internet of Things. A key challenge is to achieve the self-powering of sensors and stable operation of precision instruments. This paper introduces a dual-functional structure (VIPEH) integrating energy harvesting (EH) and vibration isolation (VI) based on the quasi-zero stiffness (QZS) piezoelectric mechanism. The paper analyzes the nonlinear statics of piezoelectric flexible beams under large deformations and conducts parametric analysis. A nonlinear dynamic model with electromechanical coupling was developed to investigate the impact of mechanical and electrical parameters on the system's dynamic bifurcation behavior, EH, and VI performance. Finally, an experimental setup is created to evaluate the VIPEH's characteristics. Sweep frequency excitation experiments demonstrate that the initial isolation frequency of VIPEH is lower than 1.4 Hz. The important thing is that VIPEH can still power the sensor based on the isolation frequency, and the output power of a single piezoelectric material can reach 3.19 mW. This not only enables the isolation of low-frequency vibrations but also presents a highly promising application for achieving self-powering in sensor clusters within the context of Industry 4.0 and the IoTs.

A magnetic/force coupling assisted lithium-oxygen battery based on magnetostriction and piezoelectric catalysis of CoFe2O4/BiFeO3 cathode

The high energy density of Li−O2 batteries surpasses all existing batteries, and it holds the potential to emerge as the most outstanding solution for energy storage in the future. However, the insulated, insoluble discharge product (Li2O2) has impeded the practical applications. Conventional catalyst design based on electronic structure and interfacial charge transfer descriptors are incapable of overcoming these limitations of Li2O2. Herein, a magnetic/force coupling assisted Li−O2 battery based on magnetostrictive and piezoelectric catalysis with CoFe2O4/BiFeO3 core-shell structure cathode was established for the first time. An external magnetic field is introduced to produce a magnetostrictive stress on CoFe2O4, contributing to the piezoelectric electron hole transport by the generated piezoelectric potential energy with a built-in electric field based on the piezoelectric catalytic mechanism, and thus promoting the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics, and reducing the overpotential during charge/discharge. The magnetic/force coupling assisted Li−O2 battery equipped with the unique CoFe2O4/BiFeO3 cathode deliver an ultra-low charging platform of 3.49 V and an ultra-high discharge platform of 2.83 V. This unique magnetic/force assisted strategy provides an important insight into solving the high overpotential in metal-air battery systems.

Self-diagnosis of structural damage in self-powered piezoelectric composites

At present, nondestructive testing and non-self-powered structure health monitoring methods are usually used to judge the damage of fiber reinforced composites. However, these methods have some limitations due to the lack of real-time characteristics, the need for external power supply or the complex structure of sensor. In this work, the piezoelectric nanogenerator mechanism was integrated into the traditional composites to develop the piezoelectric composite with damage self-diagnosis function. The piezoelectric composites can realize structural health monitoring and damage localization without reducing the original mechanical properties. The effects of PVDF and barium titanate on the mechanical properties of the composites were investigated by experiments and simulations. Furthermore, the damage self-diagnosis characteristics of composites under bending load and impact load were studied. The algebraic relationship between the damage area and the open circuit voltage under impact load was established. In addition, the damage localization of composite materials is realized by designing an Application (APP). In general, this work has successfully set a precedent for the application of nanogenerator mechanism to the self-powered and self-diagnosis of composite damage, which has the potential to be used in any field related to composites, such as aerospace, etc.

Enhanced vertical piezoelectricity in nano-switch diamane structures by super-dipole-moment effect

The lack of the vertical piezoelectricity and the corresponding internal physical mechanism of diamanes limit their applications in the piezoelectric field. The vertical piezoelectricity of the diamane doped with Si/Ge atoms is studied systematically by the first principles calculation. These monolayer diamanes can be regarded as the vertical piezoelectric nano-switches with a moderate barrier. Based on the 25 kinds of monolayers' data, the super-dipole-moment effect is found as the internal mechanism of larger vertical piezoelectricity based on the ordered phase of Born effective charges. It may deepen the understanding of the internal physical mechanism about the piezoelectricity.

Efficient degradation of organics by ultrasonic piezoelectric effect on CuO-BTO/AFC composite

The recombination of photoexcited electron–hole pairs greatly limits the degradation performance of photocatalysts. Ultrasonic cavitation and internal electric field induced by the piezoelectric effect are helpful for the separation of electron–hole pairs and degradation efficiency. The activated foam carbon (AFC) owing to its high surface area is often used as the substrate to grow catalysts to provide more reactive active sites. In this work, CuO@BaTiO3 (CuO@BTO) heterostructure is prepared by hydrothermal method on the surface of AFC to investigate the ultrasonic piezoelectric catalysis effect. X-ray diffraction (XRD), Raman spectroscopy, energy dispersive x-ray spectroscopy (EDS) and scanning electron microscopy (SEM) were used to analyze the structure and morphology of CuO-BTO/AFC composite. It is found that the CuO-BTO/AFC composite exhibits excellent piezo-catalytic performance for the degradation of organics promoted by ultrasonic vibration. The CuO-BTO/AFC composite can decompose methyl orange and methylene blue with degradation efficiency as high as 93.9% and 97.6% within 25 min, respectively. The mechanism of piezoelectricity enhanced ultrasound supported catalysis effect of system CuO-BTO/AFC is discussed. The formed heterojunction structure between BTO and CuO promotes the separation of positive and negative charges caused by the piezoelectric effect.

In Situ Piezoelectric-Catalytic Anti-Inflammation Promotes the Rehabilitation of Acute Spinal Cord Injury in Synergy.

Relieving inflammation via scavenging toxic reactive oxygen species (ROS) during the acute phase of spinal cord injury (SCI) proves to be an effective strategy to mitigate secondary spinal cord injury and improve recovery of motor function. However, commonly used corticosteroid anti-inflammatory drugs show adverse side effects which may induce increased risk of wound infection. Fortunately, hydrogen (H2), featuring selective antioxidant performance, easy penetrability, and excellent biosafety, is being extensively investigated as a potential anti-inflammatory therapeutic gas for the treatment of SCI. In this work, by a facile in situ growth approach of gold nanoparticles (AuNPs) on the piezoelectric BaTiO3, a particulate nanocomposite with Schottky heterojunction (Au@BT) is synthesized, which can generate H2 continuously by catalyzing H+ reduction through piezoelectric catalysis. Further, theoretical calculations are employed to reveal the piezoelectric catalytic mechanism of Au@BT. Transcriptomics analysis and nontargeted large-scale metabolomic analysis reveal the deeper mechanism of the neuroprotective effect of H2 therapy. The as-prepared Au@BT nanoparticle is first explored as a flexible hydrogen gas generator for efficient SCI therapy. This study highlights a promising prospect of nanocatalytic medicine for disease treatments by catalyzing H2 generation; thus, offering a significant alternative to conventional approaches against refractory spinal cord injury.