Commercial LED Research Articles

Mechanical and antimicrobial properties of green and photoactive AgTiO2/poly(3hydroxybutyrate) (PHB) electrospun membranes

AbstractThe rise of antibiotic‐resistant microbes and concerns over non‐biodegradable waste highlight the need for innovative materials with integrated functionalities that address these critical issues. In this study, we synthesized poly(3hydroxybutyrate) (PHB) electrospun nanofibers blended with gelatin (Ge) and loaded with photoactive AgTiO2 nanoparticles with improved mechanical and biological properties. Biological tests revealed excellent antibacterial activity of the prepared membrane, with efficiency exceeding 99% against Escherichia coli and 95% against Staphylococcus epidermidis after 90 and 60 min of exposure to low‐power commercial LED lights, respectively. Filtration studies using a dead‐end stainless‐steel cell reveal that both bacteria are eliminated (>99% after one filtration cycle). Results of the viability test showed that blending PHB with Ge improves the membrane's anti‐biofouling properties. The membranes were also characterized using SEM and EDX mapping techniques for morphological and elemental analysis, DSC and TGA to evaluate thermal properties and crystallinity, and FTIR to confirm chemical structure. Moreover, the electrospun membranes exhibited enhanced mechanical properties with the addition of Ge. PHB/Ge/3 wt% AgTiO2 sample showed 2.2 times better tensile strength and 1.89 times improved Young's modulus compared to PHB membranes. Finally, the breakdown of PHB/Ge/AgTiO2 membranes occurred progressively over only 8 weeks, showing the membranes' green and sustainable nature.Highlights Antibacterial efficacy of 99% against E. coli and 95% against S. epidermidis. Microfiltration efficiency >99% achieved in one filtration cycle. Mechanical strength is enhanced by 2.2 times with the addition of gelatin. Effective anti‐biofouling is confirmed by CLSM and SEM tests. Membranes degraded within 8 weeks in natural soil.

A novel pendulum-like deformation-limited piezoelectric vibration energy harvester triggered indirectly via a smoothly plucked drive plate

Vibration energy harvesting using the piezoelectric effect is emerging as a promising sustainable energy solution for micro-electromechanical systems and wireless sensor networks. Nevertheless, the advancement of piezoelectric vibration energy harvesters has been hindered by reliability issues stemming from piezoelectric material damage due to excessive deformation. To address this challenge, a pendulum-like deformation-limited piezoelectric vibration energy harvester triggered indirectly via a smoothly plucked drive plate (D-LPVEH) is proposed. The D-LPVEH effectively constrains the maximum deformation of the piezoelectric beam, enabling unidirectional deformation and enhancing reliability even under unexpected impacts, by introducing a drive plate. Simulation and experimental findings both validate the efficacy of limiting the piezoelectric beam’s deformation by integrating the drive plate structure. Besides, the D-LPVEH has a good environmental adaptability and designability, which means D-LPVEH can work in different frequency ranges by adjusting proof mass and mass arm length, even at low frequency environmental vibrations of a few Hertz. Moreover, the D-LPVEH demonstrates a peak output power of 0.77 mW at a mere 5.6 Hz, with an optimal load resistance of 100 kΩ, and can consecutively illuminate a minimum of 100 commercial blue LEDs. The D-LPVEH has demonstrated to have good power generation and high reliability. This design will provide a reference for the research on improving the reliability of PVEH.

Reactive carbon dots/polysiloxane composites cross-linked silicone resin adhesives for stable white LED constructing

Current high-performance commercial white LEDs typically rely on Ce:Y3Al5O12 (Ce:YAG) phosphors and their dispersed encapsulating material. However, Ce:YAG often has large particle sizes and does not react with the encapsulating material, causing stratification and sedimentation. To address this problem, a novel reactive carbon dots/polysiloxane (R-CDs/PS) composite was synthesized through a one-step solvothermal process involving citric acid, urea, 3-aminopropyltriethoxysilane (APTES), and vinyltrimethoxysilane (VTMS). The composite exhibits yellow emission at 528 nm under UV excitation and has a particle size of approximately 150 nm. To improve integration, vinyl adhesive (vinyl AD) and vinyl MDQ resin were designed and synthesized to enhance adhesion and mechanical strength. When dispersed in silicone resin adhesives (SRAs), R-CDs/PS composite forms a stable color conversion layer, avoiding stratification due to its nanoscale size and chemical cross-linking with SRAs. White LEDs can be easily produced by casting R-CDs/PS composites and SRAs onto LED chips, followed by high-temperature curing. These LEDs exhibit desirable optical properties, including CIE coordinates of (0.33, 0.34), a CRI of 82.2, and a CCT of 5355 K, making them suitable for indoor lighting. This study not only introduces a practical approach for fabricating fluorescent and encapsulating materials but also offers a valuable strategy for improving the stability of white LEDs.

A low-cost self-powered triboelectric nanogenerator sensor for detecting loosening bolt under impact loading

PurposeThe purpose of this study is to detect the bolt loosening under conditions of impact loading with a low-cost self-powered triboelectric nanogenerator sensor.Design/methodology/approachIn this work, an Al/PTFE-based triboelectric nanogenerator (AP-TENG) is used as a sensor. A pendulum impact device and a force hammer were used to apply the impact loads. The bolt status and the applied torque can be monitored under impact loading conditions by using the output voltage results of the AP-TENGs.FindingsThe output voltage results of the current AP-TENG sensor under five different bolt torques, i.e. from 0.5 to 2.5 N m, were measured. The measurements revealed that a thicker buffer layer significantly contributed to the generation of higher voltages. Besides, the AP-TENG was also used to light ten commercial green LEDs in series, and the brightness of the LEDs was high enough even for the daytime, which showed that it can be used as the alarm device. In addition, a sudden loose test was also carried out, and the obvious voltage spikes can be seen without the external impact. The force hammer impact tests have expanded the application scope of the AP-TENG in the bolt loosening detection.Originality/valueThe bolt loosening monitoring is important and useful for the safe operation. The application of TENG technology for detecting bolt loosening remains relatively unexplored. In addition, ten commercial green LEDs can be driven by the AP-TENG sensor, which can be used for the early warning of the bolted loosening status.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2024-0216/

High‐performance triboelectric nanogenerators boosted by synergistically aligned piezoelectric/conductive composite nanofibers

AbstractTo address the need for efficient, flexible, and wearable power sources for portable electronics, a high performance triboelectric nanogenerator (TENG) was proposed by incorporating vertically‐aligned barium titanate (BaTiO3)/antimony tin oxide (ATO) nanofibers in polydimethylsiloxane (PDMS) negative triboelectric layer, where BaTiO3 served as piezoelectric material, and ATO served as conductive filler. Silver‐coated conductive fabric was used as electrode to ensure integrability and wearability. By strategically coupling the triboelectric effect of PDMS, the piezoelectric effect of BaTiO3 nanofibers, and the charge transfer effect of ATO nanofibers, the TENG exhibited the optimum output voltage and current of approximately 119 V and 28 μA, and power density of 11.74 μW/cm2, respectively. This device demonstrates its potential applications in energy supply by effectively illuminating 174 commercial green LEDs and charging capacitors for powering electronics. Additionally, the successful integration of the TENG into a smart fencing jacket highlights its utility in practical applications.Highlights TENGs with vertically‐aligned BaTiO3/ATO composite nanofibers was constructed. The output performance of TENGs were enhanced by coupling triboelectric and piezoelectric effects. Conductive ATO nanofibers were incorporated to enhance charge transfer for performance enhancement. A smart fencing jacket with scoring system was developed using the wearable TENG.

Design, fabrication, and characterization of a deformation-restricted piezoelectric vibration energy harvester triggered by a stopper

Vibration energy harvesting based on piezoelectric effect is emerging as a promising sustainable energy solution for micro-electromechanical systems and wireless sensor networks. Whereas, reliability issues stemming from excessive deformation-induced damage to piezoelectric materials have hindered the progress of piezoelectric vibration energy harvester development. Herein, an indirect triggering method involving a stopper has been implemented to design the deformation-restricted piezoelectric vibration energy harvester (D-RPVEH). This device utilizes the stopper to limit the maximum deformation of the piezoelectric beam, facilitating unidirectional deformation. Consequently, the D-RPVEH delivers enhanced reliability even under unexpected excessive impacts. The feasibility of the proposed principle and design are proved by finite element simulation and experimental test. Most importantly, the research results are found that the simulated end displacement and experimental voltage of PZT beam declined with the decrease of stopper height difference. Moreover, the efficacy of limiting the piezoelectric beam's maximum deformation by implementing the stopper structure is supported by both simulation and experimental findings. The D-RPVEH device can achieve a peak power output of 2.58 mW at frequencies as low as 5.5 Hz, utilizing an optimal load resistance of 30 kΩ. Furthermore, it can illuminate a minimum of 60 blue commercial LEDs connected in series. Therefore, the D-RPVEH not only has good power generation performance but also has high reliability. This design will provide a reference for the research on improving the reliability of PVEH.

Improvement of temporal light artefact effects in commercial LED lamps

Temporal light modulation and its potential adverse visual effects on human observers, collectively known as temporal light artefacts (TLAs), have been limited by the European Union Ecodesign regulation. Limitations on two key TLA metrics, flicker and stroboscopic effect, were introduced in September 2021. This study analyses the impact of this regulation on commercial LED lamps by measuring multiple different consumer-grade LED E27 retrofit lamps by several manufacturers before and after the regulation. The lamps purchased after the Ecodesign regulation seem to favour a certain type of LED driver that provides the best TLA behaviour of all lamp types. The regulation, with respect to TLA, has resulted in the replacement of ill-behaving lamp types in the market by newer lamps with better TLA characteristics.

Enhanced performance of polydimethylsiloxane-based triboelectric nanogenerator using BaTiO3/MWCNTs

Triboelectric nanogenerators (TENGs) that operate in the contact-separation mode are widely utilized for energy harvesting owing to their simple structure, excellent durability, and high energy-conversion efficiency. This study investigated the enhanced performance of TENGs using polydimethylsiloxane (PDMS) incorporating barium titanate (BTO) and multiwalled carbon nanotubes (MWCNTs). The negative triboelectric layer, comprising PDMS with BTO and MWCNTs, and aluminum foil as both the positive triboelectric layer and electrode, were optimized to improve the TENG performance. The optimal composition of PDMS incorporating 0.01 wt% MWCNTs and 10 wt% BTO yielded output voltage and current of 394.75 V and 28.24 µA, respectively. Further enhancement was realized via the application of radio frequency plasma treatment, which increased the surface roughness and fluorine incorporation. Consequently, the output voltage and current improved to 421.06 V and 32.33 µA, respectively, with a peak power density of 4.76 W/m2 at 10 MΩ. The optimized TENG maintained consistent performance over 2000 cycles and successfully illuminated commercial LEDs, thereby demonstrating its potential for practical energy-harvesting applications.

A Novel Broadband Green Phosphor La2W2O9: Bi3+, and Its Application in High Color-Rendering Index pc-WLED

Broadband green phosphors have important applications in overcoming the blue-green (cyan) 470–510[Formula: see text]nm gap of phosphor-converted white LED (pc-WLED) and achieving high color rendering index (CRI) white lighting. In this work, a broadband green phosphor La2W2O9: [Formula: see text]Bi[Formula: see text] was synthesized by solid-state method. The phase, morphology and luminescence properties of the series of phosphors were systematically studied. The results showed the La2W2O9: [Formula: see text]Bi[Formula: see text] green phosphor exhibits a wide emission band in the range of 400–800[Formula: see text]nm with full width at half-maximum (FWHM) of 164[Formula: see text]nm, filling the cyan gap and reaching its peak at 550[Formula: see text]nm. The phosphor exhibits broadband excitation, and the excitation range covers the wavelength region of 200–500[Formula: see text]nm, and matches well with commercial ultraviolet LED. With the obtained broadband green phosphor, commercial CaAlSiN3:Eu[Formula: see text] red phosphor, commercial BaMgAl[Formula: see text]O17:Eu[Formula: see text] blue phosphor, and a 365[Formula: see text]nm commercial chip, a warm white pc-WLED device with a high color-rendering index (Ra[Formula: see text]97.4, R1–R15[Formula: see text]90) and low correlated color temperature (CCT[Formula: see text]3610[Formula: see text]K) was fabricated. The results demonstrate the wide range of applications for La2W2O9:Bi[Formula: see text] phosphor in the field of premium warm white LED lighting.

Printed-scalable microstructure BaTiO3/ecoflex nanocomposite for high-performance triboelectric nanogenerators and self-powered human-machine interaction

Triboelectric sensing technology reinforced with deep learning algorithm has shown significant potentials in the fields of sophisticated wearable devices and Internet of Things (IoT) applications. Herein, we present a large-scale and printable nanocomposite film for high-performance microstructured BaTiO3/Ecoflex triboelectric nanogenerator (MBE-TENG) and demonstrate its applications in deep-learning assisted self-powered sensing and human-machine interaction. The MBE-TENG device achieves a short-circuit current of 1.46 μA, an open-circuit voltage of 144 V, and a transfer charge density of 6.62 nC/cm². Additionally, the MBE-TENG device can charge a 10 μF capacitor from 0 to 2 V within 200 seconds, illuminate over 70 commercial LEDs, and power a digital calculator. Based on the MBE-TENG, a sensory array keyboard is demonstrated to wirelessly control the movement of a smart car via Bluetooth communication. Furthermore, a smart tactile sensing glove is developed by combining the MEB-TENG, residual neural network and convolutional block attention module, realizing the facile recognition on six different objects with a high accuracy of 96.33 %. This work presents a scalable fabrication for microstructured triboelectric layer and highlights the versatility and efficiency of TENG sensing technology when combined with advanced neural networks and embedded systems, paving the way for innovative development in human-machine interaction, personalized healthcare, and intelligent control interfaces.

High performance (K,Na)NbO3-based textured ceramics for piezoelectric energy harvesting

Piezoelectric energy harvesters (PEHs), which can provide sustainable green energy for low-power electronics have received extensive attention in the viewpoint of science and industrialization. In order to achieve large output power of PEHs, high-performance piezoelectric materials are extremely desired. Herein, excellent electromechanical conversion properties of d33 ∼ 447 pC/N, g33 ∼ 30 × 10−3 Vm/N, k33 ∼ 47 % and Suni ∼0.18 % were achieved in <001> grain aligned KNN-based lead-free ceramics with a favorable rhombohedral (R), orthorhombic (O) and tetragonal (T) multiphase structure. The superior electromechanical conversion properties can be attributed to grain orientation and crystal symmetry controlled anisotropy, and multiphase coexistence significantly decreased poling energy barrier, as well asthe flexible response of the nanometer domains to external stimuli. The PEHs fabricated using the optimal performance KNN-based textured ceramics exhibit high output power of 0.46 mW and power density of 6.7 mW/cm3 at a resonant frequency of 41 Hz, which is associated with the large k33 (∼47 %) and figure-of-merit (d33×g33 ∼ 13.4 × 10−12 m2/N) values. The output power can actually light up more than 145 commercial LEDs, demonstrating great potential of KNN-based PEHs to power wireless sensors.

Isotropically Polarized Bipiezoelectric Polyacrylonitrile-Poly(vinylidene Fluoride) Advanced Triboelectric Nanogenerator for Operation in High-Humidity Environments.

Conventional hybrid piezo-triboelectric nanogenerators (PTNGs) have potential applications as energy supply devices for microelectronic devices, but their low power density and unstable performance under high-humidity conditions are challenges that need to be solved. Here, we report a novel flexible hybrid bifiezo-triboelectric nanogenerator (Bi-PTNG) based on isotropic polarization design of piezoelectric PVDF and PAN nanofiber membranes, which greatly improves power density of devices and performances in high-humidity conditions. The performance enhancement mechanism of the Bi-PTNG was investigated by model analysis, experimental measurements, and simulations. The results showed that the power density output of Bi-PTNG increased by approximately 88% compared to that of a depolarized PAN/PVDF-based triboelectric nanogenerator (TENG). The application studies demonstrated that a 2 × 2 cm2 Bi-PTNG can be directly used to run more than 120 commercial LEDs, and this highly flexible and breathable all-fiber device can be integrated into clothing or insoles to monitor human movement in high-humidity conditions. This work not only provides an effective strategy for enhancing the power output of TENGs and advancing their practical applications but also offers robust guidance for the material selection and optimization of the polarization direction in such nanogenerators.

Broadband SWIR emission through Cr3+-Ni2+ energy transfer in YAGG fluorescent ceramics for bioimaging applications

Short-wave infrared (SWIR) light in the 1000–1700 nm range has high penetration capability through biological tissues and is non-destructive, making it widely used in biomedical applications and near-infrared imaging. Currently, the development of SWIR light sources is urgently needed. This paper discusses the luminescent properties of the near-infrared emitting transition metal ions Cr3+ and Ni2+. By using the traditional high-temperature solid-state method, we successfully synthesized YAGG:3.5 %Cr3+-0.5 %Ni2+ (YAGG:Cr-Ni) garnet-based phosphor ceramic in one step. The phosphor ceramic emits ultra-broadband NIR-I (600–900 nm, FWHM=131 nm) and SWIR (1100–1700 nm, FWHM=377 nm) light when excited by a 450 nm commercial blue LED. Position analysis combined with density functional theory (DFT) simulation confirmed the effective substitution of luminescent center ions for the [Al/GaO6] sites. Spectral and lifetime analyses further verified the energy transfer process between Cr3+ and Ni2+ is dipole-quadrupole interaction. Additionally, this phosphor ceramic has a high thermal conductivity of 8.018 W·m⁻¹·K⁻¹ at room temperature. Finally, SWIR pc-LED devices were fabricated by packaging the phosphor ceramic with a 450 nm commercial blue LED, achieving skeletal and venous imaging of biological tissues up to 20 mm thick, providing a new approach for the development of SWIR devices.

Efficient and Near-Zero Thermal Quenching Cr3+-Doped Garnet-Type Phosphor for High-Performance Near-Infrared Light-Emitting Diode Applications.

In recent years, near-infrared (NIR) phosphors have attracted great research interest due to their unique physical properties and broad application prospects. However, obtaining NIR phosphors with both high quantum efficiency and excellent thermal stability remains a great challenge. In this study, novel NIR Ca3Mg2ZrGe3O12:Cr3+ phosphors were successfully prepared using a high-temperature solid-phase method, and the structure and luminescent properties of the material were systematically investigated. Ca3Mg2ZrGe3O12:0.01Cr3+ emits NIR light in the range of 600 to 900 nm with a peak at 758 nm and a half-height width of 89 nm under the excitation of 457 nm blue light. NIR luminescence shows considerable quantum efficiency, and the internal quantum efficiency of the optimized sample is up to 68.7%. Remarkably, the Ca3Mg2ZrGe3O12:0.01Cr3+ phosphor exhibits a near-zero thermal quenching behavior, and the luminescence intensity of the sample at 250 °C maintains 92% of its intensity at room temperature. The mechanism of high thermal stability has been elucidated by calculating the Huang Kun factor and activation energy. Finally, NIR pc-LED devices prepared from Ca3Mg2ZrGe3O12:0.01Cr3+ phosphor with commercial blue LED chips have good performance, proving that this Ca3Mg2ZrGe3O12:0.01Cr3+ NIR phosphor has potential applications in night vision and biomedical imaging.

A novel Mn4+-doped Li2Mg4TiO7 red-emitting phosphor for warm white light-emitting diodes

To improve the light quality of warm white-LEDs (w-LEDs), novel Mn4+-activated red-emitting phosphors that can be excited efficiently by blue light with yield high performance are highly imperative. Here, we report a Mn4+-doped Li2Mg4TiO7 (LMT) phosphor prepared via a traditional high-temperature reaction method. The crystal structure and luminescent properties of the LMT:Mn4+ phosphors are studied. An excitation band centered at 470 nm, matches well with the commercial blue LED chips. Upon blue light excitation, a broadband red emssion located at 673 nm due to d-d transitions of Mn4+ is observed. The optimum doping concentration of Mn4+ is determined to be x = 0.08 %. The optimized red-emitting phosphor LMT:Mn4+ attains a photoluminescence quantum yield (PLQY) of 40.0 % and a good thermal resistance (ΔE = 0.43 eV). The combination of the as-obtained red-emitting phosphor, commercially available yellow phosphor, and blue LED chip yields a warm w-LED device, delivering CIE (x, y) = (0.3922, 0.3909), CRI = 70.0 and CCT = 2214 K. Therefore, this work provides a novel LMT:Mn4+ phosphor as a potential red component for warm w-LEDs.

Enhanced photocatalytic activity of titanium-doped copper ferrite for methyl green dye degradation under commercial visible LED light

This study examines the effect of TiO₂ doping on the catalytic performance of copper ferrite (CuFe₂O₄) nanoparticles in degrading methyl green dye under visible light. Copper ferrite nanoparticles were synthesized and doped with varying TiO₂ concentrations. The catalysts were characterized using XRD, SEM, EDX, and BET surface area analysis. The TiO₂-doped copper ferrite catalysts showed significantly enhanced catalytic activity compared to undoped copper ferrite. The optimal doping concentration of 10 wt% TiO₂ achieved a degradation efficiency of 92 % for methyl green dye after 60 min of irradiation. The BET surface area increased with TiO₂ doping, contributing to the improved catalytic performance. Reusability tests over five cycles indicated a slight decrease in efficiency, attributed to the loss of active sites. These results indicate that TiO₂ doping effectively enhances the catalytic properties of copper ferrite, making it a viable option for environmental remediation.

Investigating the physicochemical, optical and microstructural properties of sodium doped CdO nano powders fabricated by co-precipitation technique for blue emission and antimicrobial applications

A series of cubic structured pristine and sodium doped CdO nanoparticles (Cd1-xNaxO NPs) with varying dopant concentrations have been synthesized using simple Co-precipitation process. Crystal structure and the connection between various structural parameters are evidenced using powder XRD diffractograms. The crystallite size is evaluated with different models and the mean crystallite size was reduced with Na ions doping concentration due to severe lattice distortion. The existence of various vibrational modes and functional groups were demonstrated through FTIR characterization. The signature of Cd–O and Na–O stretching modes were confirmed with FTIR. Raman spectra also confirmed the formation of metal–oxygen bond and the second order vibration features. The direct bandgap of the CdO material increased from 2.132 to 2.40 eV with an increase in the Na dopant content which presents the appearance of a blue shift as probed through UV–Vis spectroscopy. The surface morphology and microstructure of the samples were studied using FESEM and HRTEM images, respectively. EDAX measurements revealed the presence of Cd, and O in the host lattice and Cd, O and Na in the doped CdO constructions. The SAED concentric ring pattern of Cd1-xNaxO nanoparticles demonstrated the polycrystalline nature of the samples. PL study revealed the impression of intrinsic defects and the photoluminescence colour emission of the Cd1-xNaxO materials shifted more towards bright blue region as the Na doping concentration increased. CIE color coordinates of Na-doped CdO NPs shows intense bluish color and extending its applications in commercial UV lighting, blue LEDs and Fluorescent biological labelling and tagging. Cd1-xNaxO nanoparticles exhibited enhanced antibacterial activity with increasing Na doping content towards gram-positive, and gram-negative bacteria. Further, the antifungal analysis against C. albicans, and A. niger authenticate that Na+ substituted CdO nanoparticles shows excellent antifungal activity. The mechanism of the above observed results is examined in detail in this article.

Sustainable, eco-friendly, and cost-effective energy generation based on coffee grounds for self-powered devices and alarm systems

The Internet of Things (IoT) requires non-pollution energy sources to power small electronic devices. These energy sources can be harvested using triboelectric nanogenerators formed by lightweight and eco-friendly components. Herein, we develop a novel triboelectric layer of coffee grounds for a triboelectric nanogenerator with ability to harvest the vibration energy and transform it into electrical energy. This layer of coffee grounds has a simple electromechanical configuration that simplifies the collocation of the nanogenerator on irregular topologies of vibration sources. This device uses sustainable and eco-friendly components, achieving a stable electromechanical behavior close to 22500 operating cycles. With a load resistance of 39.97 MΩ, our device can generate an output power density of 75.48 mWm−2 under vibration of 3 g at 25 Hz. This device lighted 116 blue commercial LEDs and powered a thermohydrometer and a digital chronometer. Furthermore, an emergency alarm button with Arduino was implemented using the nanogenerator. The proposed device can be used to generate low-cost sustainable energy for applications in IoT devices.

Core-sheath PVDF hollow porous fibers via coaxial wet spinning for energy harvesting

Flexible piezoelectric nanogenerators (PENGs), as a promising sustainable power source in smart electronics, have attracted much attention for their potential applications in the Internet of Things. In this paper, poly(vinylidene fluoride) (PVDF) fibers with core-sheath hollow porous structure were prepared by coaxial wet spinning process, serving as the dielectric layer, which were perfused internally by liquid metal (LM) as the inner electrode layer and wrapped outside by copper-silver nanoparticles (Cu@AgNP) as the outer electrode layer, thus constructing high-performance PVDF/LM/Cu@AgNP composite fibers. The composite PVDF fibers have a layered pore structure and arbitrarily deformable LM electrodes, which can significantly reduce the effective electric constant and thus enhance the piezoelectric properties. The results reveal that PVDF/LM/Cu@AgNP-PENG yields an optimal voltage output of 410 mV, providing a clear advantage over PENG by using alternative fibers. Moreover, the PVDF/LM/Cu@AgNP-PENG shows an excellent charging capability for energy storage devices, being able to charge 1 μF capacitors to 10 V within 30 s and directly power commercial LEDs. This study demonstrates the significant potential for utilizing composite PVDF piezoelectric fibers in flexible wearable electronic devices.

RGB LED for Communication, Harvesting and Sensing in IoT Applications

RGB LED bulbs have entered the market as a promising alternative to traditional phosphor-coating LEDs to meet illumination standards. In this article, we introduce and propose solutions to address the challenges of RGB LED lighting for the Internet of Things applications, performing communication, harvesting energy, and sensing tasks. Through experiments, we demonstrate that we can use RGB LEDs for multiple tasks. We can achieve a bandwidth in the order of 50 kHz and distances of around 3.5 m using commercial RGB LED bulbs as transceivers, without using any dedicated photodetector. RGB LED links are composed of three main colors, and we show that red is the best color both for communicating to another receiving RGB LED bulb, as well as for harvesting with a solar cell; green and blue can instead be exploited for standard-compliant lighting and/or sensing purposes. We evaluate the system in two proofs of concept and provide insights for operating RGB LEDs for multiple tasks including vertical farming.