Papers by Keyword: Energy Harvesting

Abstract: Achieving high-performance polymer-based piezoelectric-triboelectric nanogenerators (PTNGs) remains challenging due to the limited electroactive phase content and inefficient dipole alignment in polymer matrices. Here, we propose a liquid-metal doping strategy, supported by molecular dynamics (MD) simulations, to construct β-PVDF-LM composites with enhanced pie-zoelectric and triboelectric properties. Simulations indicate that liquid-metal atoms preferentially interact with fluorine in PVDF chains, stabilizing the all-trans conformation and promoting dipole ordering under an external electric field. In addition, the liquid metal and its native oxide layers act as electron-trapping centers during triboelectric contact, leading to higher interfacial charge storage and retention. As a result, the β-PVDF-LM composites exhibit a high β-phase fraction of 91% and deliver outstanding electrical outputs. The optimized β-PVDF-LM/PA6 PTNG achieves a peak-to-peak voltage of 1831 V, a current density of 214.3 mA/m², a charge density of 254.4 μC/m², and a maximum power density of 83.8 W/m². This work provides new in-sights into the design of liquid-metal-assisted PTNGs and highlights their potential for efficient energy harvesting.

Abstract: This study assesses the photovoltaic potential of pure Bismuth Ferrite (BiFeO₃) and its doped variants, specifically Samarium (Sm)-doped and Cobalt–Samarium (Co–Sm) co-doped BiFeO₃ nanoparticles. The materials were synthesized using sol-gel methods, followed by post-annealing to promote high crystallinity. A comprehensive characterization was performed to evaluate the structural, morphological, and optical properties utilizing X-ray diffraction (XRD), Field-Emission Scanning Electron Microscopy (FESEM), and UV-Vis spectroscopy. The findings indicate that doping and co-doping have a substantial influence on the optical bandgap, particle morphology, and crystallite dimensions. Sm and Co–Sm doping reduced the bandgap, enhancing visible-light absorption and solar energy-harvesting efficiency, whereas pure BiFeO₃ exhibited a bandgap of 2.03 eV. Electrical investigations further revealed greater charge separation, underscoring the superior charge-transport properties of the modified materials. The results indicate that doped BiFeO₃ systems hold potential as tunable multiferroic materials for advanced, high-efficiency solar applications.

Abstract: Advanced biocompatible piezoelectric composites have gained significant attention for the development of flexible medical devices and especially related to materials structures that mimic the natural tissue structures. Natural piezoelectricity within the human tissues is reviewed, together with nature-based piezoelectric materials, their advantages and potential for designing the structures for biomedical applications. Electrospun Polyvinylidene fluoride (PVDF) nanofiber matrix, reinforced with silver nanoparticles (AgNPs) is discussed, including specific applications in bone grafts, biosensors and energy harvesting. Processing parameters of the electrospinning fabrication technology have a strong influence on the composite piezoelectricity. Computational models of piezoelectric composites have become a major support in material design for the real case applications. Existing approaches to the numerical modeling of piezoelectric composites have been shortly reviewed toward a recent trend of AI supported modeling for providing effective composite properties, prediction and optimization of material properties and behavior, such as the output voltage and power. Polymer-based biomedical piezoelectric composites have shown excellent results in laboratory research from aspects of their flexibility and possibility to tailor their electro-mechanical properties. However, output piezoelectric signals are still much lower than in the case of traditional ceramic-based materials, including challenges related to the stability of the electric signal, signal noise, piezoelectric impedance and durability of composites with nature-based reinforcements. Future directions in custom composite design, including currently available computational models to enable more rapid development of biomedical piezoelectrics are elaborated at the end.

Abstract: Energy harvesting is an effective technique for optimizing Wireless Body Area Network (WBAN) devices used for continuous healthcare services delivery. Despite the growing popularity of WBANs in recent years due to their potential to transform healthcare, energy consumption remains a critical issue. This is due to several factors such as the limited capacity of batteries in smaller sensor nodes, the continuous operation that drains batteries and renders the nodes inoperable, and the impracticality of replacing batteries in situations where the sensors are implanted in the human body and would require surgical procedures to remove them. Thus, the need for research into scavenging, harvesting and utilizing available energy sources. This work proposed energy optimization of WBAN using Time Division Multiple Access (TDMA) duty cycling and thermal energy harvesting. The proposed model aims to enhance energy efficiency in a WBAN using TDMA and Thermoelectric Harvesting (TEH) techniques. At the heart of this model is an IoT controller that runs on a single-sensor activation principle at all times, controls the sensor function and stores the sensor data in its internal memory (buffer), enabling efficient data management and transfer. The TDMA scheduling ensures that multiple sensors are engaged in a coordinated manner whereby a node is enabled only when needed reducing idle time, network collisions and contention, hence contributing to energy savings which is critical to our energy optimization plan. The proposed optimization model shows a 52.40% improvement in the energy conversation of the WBAN device, thus increasing the battery’s useful life by more than 50%.

Abstract: The integration of infrared nanoantenna technology into architectural design presents a novel approach to enhancing buildings’ energy efficiency by converting ambient electromagnetic radiation, particularly in the infrared spectrum, into usable electrical power. This technology offers significant potential to reduce buildings’ reliance on external power sources, contributing to a more sustainable energy ecosystem. The development of advanced nanotechnology, metamaterials, and responsive coatings is essential for creating adaptive surfaces capable of capturing and utilizing radiant energy. Given the increasing global energy demand and the urgency to combat climate change, infrared nanoantennas represent a promising frontier in renewable energy harvesting. This paper provides a detailed examination of recent advancements in nanoantenna technology, fabrication methods, and integration strategies within building materials. Furthermore, it addresses the practical challenges of implementing these systems in architectural design, offering insights into how this emerging technology could contribute to the development of self-sustaining, energy-efficient structures.

Abstract: Energy harvesting monitoring systems have become more important as the Internet of Things (IoT) have grown. An intelligent system to monitor rainwater harvesting at UNITEN COE BN is being designed and developed in this study. Rainwater harvesting operations will be improved by developing an intelligent system. Monitoring techniques are studied, and sensors are designed for simulation. Smart rainwater harvesting systems are designed and implemented in this study, contributing to the field of smart monitoring systems. Rainwater collection, storage and usage are monitored and analyzed with smart sensors and data acquisition systems. Water turbine speed, voltage, and rainfall intensity are monitored by sensors in the developed system. Data from sensors is processed in Python GUIs. Visual displays allow users to monitor the rainwater harvesting system remotely. Durability and infrastructure compatibility are considered when selecting materials. It is found that smart rainwater harvesting system performance and reliability can be improved through simulation testing and validation. The study concluded that, storm water resources can be optimized by accessing real-time information.

Abstract: Visible light communication has advantages over acoustic and radio wave transmissions in free-space and underwater. The optical transmitters are usually light emitting diodes or laser diodes, and the optical receivers are usually photodiodes or its variants. Solar panels are used for solar energy harvesting to electricity, but the panels are also available in small sizes, and hence, are finding increasing use in optical communications due to larger aperture compared to photodiodes. This work investigated by experiments the characteristics of solar panels as receivers in visible light communication (VLC). In the work, four solar panels of different physical sizes were selected for experiments and measurement. Two characteristics important to communication were investigated. First is the internal resistance at different low illumination levels of white light. Second is response to sinusoidally varying intensity of white light at varying frequencies. For the first study, two of the four panels were investigated; and for the second study, the four solar panels were investigated. An array of seven white LEDs was used as the light source. Also, underwater data communication in saline water was performed for one of the solar panels, and a photodiode in comparison. Results showed that under steady illumination, the internal resistance is both illumination level-dependent and surface area-dependent. It decreases with increase in illumination level, and surface area. Also, the rate of decrease of the internal resistance with illumination increases with surface area. For the frequency response, the cut-off frequency of the solar panel is surface area-dependent, and load-dependent. It decreases with increase in surface area, and increases with decrease in load resistance values (increased loading). For data communication, the maximum data rate obtainable with the solar panel is less to that of the photodiode. The frequency response is important in considering the bandwidth of the solar panels, which also varies with the load, while the internal resistance is important in maximum power point tracking and impedance matching with front end circuits in optical communication receivers.

Abstract: Rotating parts such as shafts, gear wheels, ball bearings or rollers are subject to wear that limits their life cycle. Damage causes loss of production and consequential damage to the entire production plant. Based on the application in a support roller, a system design is presented with which it is possible to record and wirelessly transmit relevant measured values in or on rotating machines without an additional voltage source. The system is largely maintenance-free and can be implemented with components that are currently freely available on the market.

Abstract: Currently humans are still very dependent on resources derived from fossil fuels. Even though fossil fuels are no longer sufficient to meet energy needs. For this reason, renewable energy technology is developed in the form of energy harvesting from mechanical energy in the form of ferrofluid vibrations. The ferrofluid used in this study is composed of filler Mn_0.5Zn_0.5Fe₂O₄ where Zn doping is used to increase magnetization, surfactant tetramethylammonium hydroxide (TMAH), and H₂O as a liquid carrier. This study aims to study ferrofluid Mn_0.5Zn_0.5Fe₂O₄ as energy harvesting. Mn_0.5Zn_0.5Fe₂O₄ nanoparticles were synthesized using the coprecipitation method accompanied by nanostructure studies in the form of XRD, FTIR and VSM tests to determine the diffraction peaks, functional groups and magnetic properties of the sample. The diffraction peaks of Mn_0.5Zn_0.5Fe₂O₄ are at the peaks (2 2 0), (3 1 1), (2 2 2), (4 0 0), (4 2 2), (5 1 1), and (4 4 0). The FTIR spectrum of Mn_0.5Zn_0.5Fe₂O₄ nanoparticles is shown in the wavelength range of 4000-500 cm⁻¹. The band vibration peaks of O-H stretching, CO₂, O-H, Mn-O, Zn-O, and Fe-O particles Mn_0.5Zn_0.5Fe₂O₄ are respectively at 3392 cm⁻¹, 2309 and 2376 cm⁻¹, 1635 cm⁻¹, 861 and 1636 cm⁻¹, 686 cm⁻¹ and 539 cm⁻¹. The functional group of the metal-oxygen group (M–O) originates from magnetic particles as fillers to form ferrofluids. The competition of Mn and Zn ions at octahedral and tetrahedral sites in the spinel system tends to change the lattice parameters of the Mn_0.5Zn_0.5Fe₂O₄ ferrofluid. The magnetization curve of the Mn_0.5Zn_0.5Fe₂O₄ ferrofluid has superparamagnetic characteristics with a saturation magnetization value of 31,727 emu/g so it can be used as an energy harvester. Based on the IV electrical test, the Mn_0.5Zn_0.5Fe₂O₄ ferrofluid has the potential for energy harvesting with a voltage value of 1.67 µV and a current of 136.6 µA.

Abstract: One of the traditional clean-energy harvesting solutions is through transducing different mechanical stresses into electrical energy. Generally, the acoustic-to-electric energy conversion of still needs more research investigations to be applicable. In our work, we are targeting to fabricate elastic nanofibers mats via electrospinning method to be used for acoustic harvesting/sensing applications. The targeted mechanically-elastic nanocomposite includes polyvinylidene fluoride (PVDF), which is one of the most famous organic piezo materials, with blended thermoplastic polyurethane (TPU). As TPU supports higher mechanical allowed breaking strain. Then, the synthesized mat has been used as a target for mechanical stresses with resulted piezosensitivity of 667±220 mV/N. Then, the nanofibers mat has been targeted against acoustic signals with different amplitude and frequencies. It has been observed that the synthesized mats can detect or harvest acoustic signals and convert them into output electric voltage. According to acoustic sound input, the synthesized electrospun nanofibers detect output voltage up to 300 mV with increased input audible amplitude and frequency up to 6 kHz, where the harvested voltage has a saturation behaviour beyond that audible frequency. That can open the track for using such nanocomposites in energy harvesting applications from disposable facemasks, filters, and music/noise in different opened and closed areas.