Search Results (110)

Continuous monitoring of environmental and physiological parameters is essential for early diagnostics, real-time decision making, and intelligent system adaptation. Recent advancements in bio-microelectromechanical systems (BioMEMS) sensors have significantly enhanced our ability to track key metrics in real time. However, continuous monitoring demands sustainable energy supply solutions, especially for on-site energy replenishment in areas with limited resources. Artificial intelligence (AI), particularly large language models, offers new avenues for interpreting the vast amounts of data generated by these sensors. Despite this potential, fully integrated systems that combine self-powered BioMEMS sensing with AI-based analytics remain in the early stages of development. This review first examines the evolution of BioMEMS sensors, focusing on advances in sensing materials, micro/nano-scale architectures, and fabrication techniques that enable high sensitivity, flexibility, and biocompatibility for continuous monitoring applications. We then examine recent advances in energy harvesting technologies, such as piezoelectric nanogenerators, triboelectric nanogenerators and moisture electricity generators, which enable self-powered BioMEMS sensors to operate continuously and reducereliance on traditional batteries. Finally, we discuss the role of AI in BioMEMS sensing, particularly in predictive analytics, to analyze continuous monitoring data, identify patterns, trends, and anomalies, and transform this data into actionable insights. This comprehensive analysis aims to provide a roadmap for future continuous BioMEMS sensing, revealing the potential unlocked by combining materials science, energy harvesting, and artificial intelligence. Full article

This paper presents a comprehensive summary of recent advances in circuit topologies for piezoelectric energy harvesting, leading to self-powered systems (SPSs), covering the full-bridge rectifier (FBR) and half-bridge rectifier (HBR), AC-DC converters, and maximum power point tracking (MPPT) techniques. These approaches are analyzed with respect to their advantages, limitations, and overall impact on energy harvesting efficiency. Th work explores alternative methods that leverage phase shifting between voltage and current waveform components to enhance conversion performance. Additionally, it provides detailed insights into advanced design strategies, including adaptive power management algorithms, low-power control techniques, and complex impedance matching. The paper also addresses the fundamental principles and challenges of converting mechanical vibrations into electrical energy. Experimental results and performance metrics are reviewed, particularly in relation to hybrid approaches, load impedance, vibration frequency, and power conditioning requirements in energy harvesting systems. This review aims to provide researchers and engineers with a critical understanding of the current state of the art, key challenges, and emerging opportunities in piezoelectric energy harvesting. By examining recent developments, it offers valuable insights into optimizing interface circuit design for the development of efficient and self-sustaining piezoelectric energy harvesting systems. Full article

This study analyses the dynamic impact between winter wheat grains (‘Memory’ cultivar) and a flat metal surface under normal collisions. Four moisture levels (7%, 10%, 13% and 16%) and impact velocities from 1.0 to 4.5 m·s⁻¹ were chosen to reflect conditions in agricultural machinery. A custom test rig—comprising a transparent drop guide, a high-sensitivity piezoelectric force sensor and a high-speed camera—recorded grain velocity by vision techniques and contact force at 1 MHz. Force–time curves were examined to evaluate restitution velocity, the coefficient of restitution (CoR) and the effect of moisture on elastic–plastic deformation. CoR decreased non-linearly as impact velocity rose from 1.0 to 5.0 m·s⁻¹, and moisture content increased from 7% to 16%, falling from ≈ 0.60 to 0.40–0.50. Grains with higher moisture struck at higher velocities showed greater plastic deformation, longer contact times and intensified energy dissipation, making them more susceptible to internal damage. The data provide validated reference values for discrete element method (DEM) calibration and will assist engineers in designing grain-handling equipment that minimises mechanical damage during harvesting, conveying and processing. Full article

Polyvinylidene fluoride (PVDF) polymer films, renowned for their exceptional piezoelectric, pyroelectric, and ferroelectric properties, offer a versatile platform for the development of cutting-edge micro-scale functional devices, enabling innovative applications ranging from energy harvesting and sensing to medical diagnostics and actuation. This paper presents an in-depth review of the material properties, fabrication methodologies, and characterization of PVDF films. Initially, a comprehensive description of the physical, mechanical, chemical, thermal, electrical, and electromechanical properties is provided. The unique combination of piezoelectric, pyroelectric, and ferroelectric properties, coupled with its excellent chemical resistance and mechanical strength, makes PVDF a highly valuable material for a wide range of applications. Subsequently, the fabrication techniques, phase transitions and their achievement methods, and copolymerization and composites employed to improve and optimize the PVDF properties were elaborated. Enhancing the phase transition in PVDF films, especially promoting the high-performance β-phase, can be achieved through various processing techniques, leading to significantly enhanced piezoelectric and pyroelectric properties, which are essential for diverse applications. This concludes the discussion of PVDF material characterization and its associated techniques for thermal, crystal structure, mechanical, electrical, ferroelectric, piezoelectric, electromechanical, and pyroelectric properties, which provide crucial insights into the material properties of PVDF films, directly impacting their performance in applications. By understanding these aspects, researchers and engineers can gain valuable insights into optimizing PVDF-based devices for various applications, including energy-harvesting, sensing, and biomedical devices, thereby driving advancements in these fields. Full article

Wave energy is one of the most reliable and promising renewable energy sources that has attracted lots of attention, including piezoelectric wave energy harvesting devices. One of the challenges for piezoelectric wave power generation is the relatively low-frequency wave environments in the ocean. Magnetic excitations are one of the techniques used to overcome this issue. However, there is a lack of understanding of the mechanisms to maximize the electric power output of piezoelectric wave energy harvesters through magnetic excitations. In the present study, magnetic excitation experiments were conducted to investigate the power generation of a coupled spring pendulum piezoelectric energy harvester under various magnetic field conditions. Firstly, the mass of the load magnet that can induce the resonance phenomenon in piezoelectric elements was experimentally determined. Then, the power generation of piezoelectric elements was tested under different excitation magnetic spacings. Finally, the influence of different distribution patterns of excitation magnets on the performance of piezoelectric elements was tested. It was found that under the conditions of a load magnet mass of 2 g, excitation magnet spacing of 4 mm, and two excitation magnets stacked on the inner pendulum, optimum power generation of the piezoelectric wave harvester was achieved with a peak-to-peak output voltage of 39 V. The outcome of this study provides new insight for magnetic excitation devices for piezoelectric wave energy harvesting to increase the feasibility and efficiency of wave energy conversion to electrical energy. Full article

Graphene-based piezoelectric nanogenerators (PENGs) have emerged as a promising technology for sustainable energy harvesting, offering significant potential in powering next-generation electronic devices. This review explores the integration of graphene, a highly conductive and mechanically robust two-dimensional (2D) material, with PENG to enhance their energy conversion efficiency. Graphene’s unique properties, including its exceptional electron mobility, high mechanical strength, and flexibility, allow for the development of nanogenerators with superior performance compared to conventional PENGs. When combined with piezoelectric materials, polymers, graphene serves as both an active layer and a charge transport medium, boosting the piezoelectric response and output power. The graphene-based PENGs can harvest mechanical energy from various sources, including vibrations, human motion, and ambient environmental forces, making them ideal for applications in wearable electronics, and low-power devices. This paper provides an overview of the fabrication techniques, material properties, and energy conversion mechanisms of graphene-based PENGs, and integration into real-world applications. The findings demonstrate that the incorporation of graphene enhances the performance of PENG, paving the way for future innovations in energy-harvesting technologies. Full article

Biodegradable piezoelectric polymers have emerged as a hot research focus in bioelectronics, energy-harvesting systems, and biomedical applications, as well as in sustainable future development. Biopolymers possess plenty of features which make them promising candidates for next-generation electronic technologies, including biocompatibility, degradability, and flexibility. This review discusses piezoelectric biopolymers, focusing on the relationship between coupling mechanisms, material structures, and piezoelectric performance. Processing techniques such as annealing, mechanical drawing, and poling are introduced and further studied in terms of achieving high piezoelectric performance. This work reviews the strategies for enhancing piezoelectric properties via molecular engineering, nano structuring, and the incorporation of additives. Furthermore, the applications of these biopolymers in energy harvesting and biomedicine are provided, with a discussion of their potential in degradable bioelectronic devices. There are still challenges in optimizing piezoelectric performance and ensuring stability. Our research is expected to provide an understanding of these challenges and help to achieve a wider application of piezoelectric biopolymers. Full article

This paper investigates the synthesis and characterization of eco-friendly piezoelectric composite thin films composed of chitosan and Ln₂O₃-doped Na_0.5Bi_0.5TiO₃-BaTiO₃ (NBT-BT) nanoparticles. The films were fabricated using a solution-casting technique, successfully embedding the particles into the chitosan matrix, which resulted in enhanced piezoelectric properties compared to pure chitosan. Characterization methods, such as photoluminescence spectroscopy and piezo-response force microscopy (PFM) which revealed strong electromechanical responses, with notable improvements in piezoelectric performance due to the inclusion of NBT-BT nanoparticles. X-ray diffraction (XRD) analysis revealed a pure perovskite phase with the space group R3c for NBT-BT and NBT-BT-Ln particles. Scanning electron microscopy (SEM) images showed a non-uniform distribution of NBT-BT particles within the chitosan matrix. The results also suggest that the incorporation of rare earth elements further enhances the electrical and piezoelectric properties of the composites, highlighting their potential in flexible and smart device applications. Overall, these findings underscore the potential of chitosan-based composites in addressing environmental concerns while offering effective solutions for energy harvesting and biomedical applications. Full article

Numerous recent studies address the concept of energy harvesting from natural wind excitation vibration to piezoelectric surfaces, aerodynamic losses, and electromagnetic dampers. All these techniques require a connection to an energy-management circuit. However, the simulation model for energy conversion and management dedicated to this task has not yet been described. This paper presents a model-based simulation for an energy conversion system using piezoelectric energy-harvester system (PEHS) technology. A controlled pulse width modulation (PWM) rectifier, a closed-loop buck-boost converter, and a piezoelectric transducer comprise a dynamic mathematical model of a PEHS. The control blocks of the closed-loop buck-boost converter use the perturbation and observation (P&O) algorithm based on maximum power point tracking (MPPT), which adapts the operational voltage of the piezoelectric source to deliver the maximum power to load. A simulation program is employed to perform mathematical analysis on various wind vibration scenarios, piezoelectric sources without PWM converters, and piezoelectric vibration sources connected to a closed-loop P&O converter. The crucial results of this paper demonstrated that the proposed dynamic PEHS model effectively fed low-power electronic loads by directly adjusting the output voltage level to the set voltage, even under different vibration severity levels. As a result, the proposed PEHS dynamic model serves as a guideline for researchers in the development of self-powered sensors, which contributes to understanding sustainable energy alternatives. Full article

The rise of the Internet of things has catalyzed extensive research in the realm of flexible wearable sensors. In comparison with conventional sensor power supply methods that are reliant on external sources, self-powered sensors offer notable advantages in wearable comfort, device structure, and functional expansion. The energy-harvesting modes dominated by piezoelectric nanogenerators (PENGs), triboelectric nanogenerators (TENGs), and pyroelectric nanogenerators (PyENGs) create more possibilities for flexible self-powered sensors. This paper meticulously examines the progress in flexible self-powered devices harnessing TENG, PENG, and PyENG technologies and highlights the evolution of these sensors concerning the material selection, pioneering manufacturing techniques, and device architecture. It also focuses on the research progress of sensors with composite power generation modes. By amalgamating pivotal discoveries and emerging trends, this review not only furnishes a comprehensive portrayal of the present landscape but also accentuates avenues for future research and the application of flexible self-powered sensor technology. Full article

This research aims to use energy harvested from conductive materials to power microelectronic components. The proposed method involves using vibration-based energy harvesting to increase the natural vibration frequency, reduce the need for battery replacement, and minimise chemical waste. Piezoelectric transduction, known for its high-power density and ease of application, has garnered significant attention. Additionally, graphene, a non-piezoelectric material, exhibits good piezoelectric properties. The research explores a novel method of printing graphene material using 3D printing, specifically Direct Ink Writing (DIW) and fused deposition modelling (FDM). Both simulation and experimental techniques were used to analyse energy harvesting. The experimental technique involved using the cantilever beam-based vibration energy harvesting method. The results showed that the DIW-derived 3D-printed prototype achieved a peak power output of 12.2 µW, surpassing the 6.4 µW output of the FDM-derived 3D-printed prototype. Furthermore, the simulation using COMSOL Multiphysics yielded a harvested output of 0.69 µV. Full article

This research aims to optimize piezoelectric implants for orthopedic applications, enhancing energy harvesting efficiency and mechanical integrity. Our objectives include comparing piezoelectric materials (PZT, PVDF, and BaTiO₃) and employing advanced theoretical modeling, finite element analysis (FEA), and validation to identify optimal configurations. Methodologically, this study integrates machine learning and AI-driven techniques to refine design parameters and predict performance outcomes. Significant findings have revealed that PZT demonstrated the highest sensitivity (2 V/mm), achieving a maximum power output of 4.10 Watts, surpassing traditional solutions by over 100%. The optimization process ensured uniform stress distribution, reducing mechanical failure risk, with predictive models showing high accuracy (R-squared value of 97.77%). Error analysis indicated minimal discrepancies, with an average error margin of less than 2%. The conclusions highlight the significant potential of optimized piezoelectric implants in developing durable, efficient, and patient-friendly orthopedic solutions, setting a new standard in intelligent medical device innovation and contributing to enhanced patient care and improved clinical outcomes. Full article

The ability to power low-power devices and sensors has drawn a great deal of interest to energy harvesting from ambient vibrations. The application of variable-length pendulum systems in conjunction with piezoelectric or electromagnetic energy-harvesting devices is examined in this thorough analysis. Because of their changeable length, such pendulums may effectively convert mechanical vibrations into electrical energy. This study covers these energy-harvesting systems’ basic theories, design concerns, modeling methods, and performance optimization strategies. This article reviews several studies that look at dynamic models, the effects of damping coefficients, device designs, and excitation parameters on energy output. The advantages and disadvantages of piezoelectric and electromagnetic coupling techniques are demonstrated by comparative research. This review also looks at technical advances and future research prospects in variable-length, pendulum-based energy harvesting. An expanded model for an energy harvester based on a variable-length pendulum derived from the modified, swinging Atwood machine is more specifically presented. This model’s numerical simulations, estimated current and voltage outputs, and produced power from the electromagnetic and piezoelectric devices integrated at various points in a 4-DOF variable-length pendulum model all indicate encouraging results. This necessitates extra study, changes, and optimizations to improve the usefulness of the proposed model. Finally, important dynamic models on developing variable-length, pendulum-based energy harvesters for usage in a range of applications to create sustainable energy are summarized. Full article

Energy harvesting is a clean technique for obtaining electrical energy from environmental energy. Mechanical vibrations are an energy source that can be used to produce electricity using piezoelectric energy harvesters. Vibrations and wind in bridges have the potential to produce clean energy that can be employed to supply energy to electronic devices with low consumption. The purpose of this paper was to validate the functioning of an energy harvester and test the electrical power generation potential of a system based on the oscillation of a rod with a tip mass to stimulate piezoelectric transducers by impact. The obtained results showed the electric energy productions for different test conditions. Experimentally, the proposed structure produced 0.337 µJ of energy after 14 s of testing. In addition, after one hour of operation, an estimated production of 10.4 mJ was obtained, considering four stacks of 25 piezoelectric disks each when periodic impacts of 50 N at 5.7 Hz stimulated the transducers. In future work, we will focus on taking advantage of the vibrations produced in the proposed structure induced by the mechanical vibration of bridges and vortex-induced vibration (VIV) through interaction with wind to produce clean energy that is useful for low-power applications. Full article

The development of innovative heterostructures made of ZnO nanowires is of great interest for enhancing the performances of many devices in the fields of optoelectronics, photovoltaics, and energy harvesting. We report an original fabrication process to form ZnO/ZnGa₂O₄ core–shell nanowire heterostructures in the framework of the wet chemistry techniques. The process involves the partial chemical conversion of ZnO nanowires grown via chemical bath deposition into ZnO/ZnGa₂O₄ core–shell nanowire heterostructures with a high interface quality following their immersion in an aqueous solution containing gallium nitrate heated at a low temperature. The double-step process describing the partial chemical conversion relies on successive dissolution and reaction mechanisms. The present finding offers the possibility to fabricate ZnO/ZnGa₂O₄ core–shell nanowire heterostructures at low temperatures and over a wide variety of substrates with a large surface area, which is attractive for nanostructured solar cells, deep-UV photodetectors, and piezoelectric devices. Full article