Abstract
For effective ocean energy harvesting, it is necessary to understand the coupled motion of the piezoelectric nanogenerator (PENG) and ocean currents. Herein, we experimentally investigate ...power performance of the PENG in the perspective of the fluid–structure interaction considering ocean conditions with the Reynolds number (
Re
) values ranging from 1 to 141,489. A piezoelectric polyvinylidene fluoride micromesh was constructed via electrohydrodynamic (EHD) jet printing technique to produce the β-phase dominantly that is desirable for powering performance. Water channel was set to generate water flow to vibrate the flexible PENG. By plotting the
Re
values as a function of nondimensional bending rigidity (
K
B
) and the structure-to-fluid mass ratio (
M*
), we could find neutral curves dividing the stable and flapping regimes. Analyzing the flow velocities between the vortex and surroundings via a particle image velocimetry, the larger displacement of the PENG in the chaotic flapping regime than that in the flapping regime was attributed to the sharp pressure gradient. By correlating
M
*,
Re
,
K
B
, and the PENG performance, we conclude that there is critical
K
B
that generate chaotic flapping motion for effective powering. We believe this study contributes to the establishment of a design methodology for the flexible PENG harvesting of ocean currents.
In the field of soft electronics, high-resolution and transparent structures based on various flexible materials constructed via various printing techniques are gaining attention. With the support of ...electrical stress-induced conductive inks, the electrohydrodynamic (EHD) jet printing technique enables us to build high-resolution structures compared with conventional inkjet printing techniques. Here, EHD jet printing was used to fabricate a high-resolution, transparent, and flexible strain sensor using a polydimethylsiloxane (PDMS)/xylene elastomer, where repetitive and controllable high-resolution printed mesh structures were obtained. The parametric effects of voltage, flow rate, nozzle distance from the substrate, and speed were experimentally investigated to achieve a high-resolution (5 µm) printed mesh structure. Plasma treatment was performed to enhance the adhesion between the AgNWs and the elastomer structure. The plasma-treated functional structure exhibited stable and long strain-sensing cycles during stretching and bending. This simple printing technique resulted in high-resolution, transparent, flexible, and stable strain sensing. The gauge factor of the strain sensor was significantly increased, owing to the high resolution and sensitivity of the printed mesh structures, demonstrating that EHD technology can be applied to high-resolution microchannels, 3D printing, and electronic devices.
—Micropumps have attracted considerable interest in micro-electro-mechanical systems (MEMS), microfluidic devices, and biomedical engineering to transfer fluids through capillaries. However, ...improving the sluggish capillary-driven flow of highly viscous fluids is critical for commercializing MEMS devices, particularly in underfill applications. This study investigated the behavior of different viscous fluid flows under the influence of capillary and electric potential effects. We observed that upon increasing the electric potential to 500 V, the underfill flow length of viscous fluids increased by 45% compared to their capillary flow length. To explore the dynamics of underfill flow under the influence of an electric potential, the polarity of highly viscous fluids was altered by adding NaCl. The results indicated an increase of 20–41% in the underfill flow length of highly viscous conductive fluids (0.5–4% NaCl additives in glycerol) at 500 V compared to that at 0 V. The underfill viscous fluid flow length improved under the electric potential effect owing to the polarity across the substance and increased permittivity of the fluid. A time-dependent simulation, which included a quasi-electrostatic module, level set module, and laminar two-phase flow, was executed using the COMSOL Multiphysics software to analyze the effect of the external electric field on the capillary-driven flow. The numerical simulation results agreed well with the experimental data, with an average deviation of 4–7% at various time steps for different viscous fluids. Our findings demonstrate the potential of utilizing electric fields to control the capillary-driven flow of highly viscous fluids in underfill applications.
A transparent water-solid contact triboelectric nanogenerator (TENG) integrated with a solar cell is expected to be a reliable source of stable energy during both dry and wet seasons. This is ...particularly significant in countries with tropical climates, where both seasons are pronounced. In this paper, a highly transparent and conductive electrohydrodynamic jet-printed Ag nanoparticle (NP) electrode-based TENG (PA-TENG) was developed and integrated with a solar cell. The fabricated PA-TENG exhibited a maximum power output of 1.17 W/m2, and average and maximum optical transmittance of 91% and 96%, respectively. The conventional indium tin oxide (ITO) electrode was selected to serve as a control group. ITO-TENG exhibited maximum and average optical transmittances of 92% and 88%, respectively. In addition, its power output was approximately three times lower than that of PA-TENG. This performance improvement of PA-TENG is attributed to the effective charge-inducing ability caused by the high contact barrier at the AgNP/polydimethylsiloxane (PDMS) interface as well as the high conductivity of the printed AgNP electrode (sheet resistance: 3.6 Ω/sq). We also find that the PA-TENG exhibits the highest transparency and power output among the reported data of the transparent water-solid contact TENG. Finally, integration of the solar cell within PA-TENG reduced its power density by 3.6% while it reduced that of ITO-TENG by 5.2%. This indicates that PA-TENG is more suitable for integration with a solar cell than ITO-TENG on both rainy and sunny days. By estimating the loss in electricity in the solar cell induced by the opacity of PA-TENG and the electricity generated by it, we concluded that PA-TENG integrated with a solar cell could serve as a potential source of stable eco-friendly energy in regions with a tropical wet-dry climate.
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•The EHD jet-printed Ag-grid electrode exhibits high transparency and conductivity.•High-performance raindrop energy-based TENG is developed with the printed Ag-grid.•Enhanced contact barrier at the AgNP/PDMS causes effective charge recombination.•The high conductivity of Ag-grid increases induced charges at the AgNP/PDMS.•The developed TENG has great potential in a hybrid nanogenerator with a solar cell.
The use of metal halide perovskite nanocrystals in display applications has garnered attention owing to their excellent optoelectronic properties, such as high color purity with an extremely narrow ...full width at half maximum and high photoluminescence quantum yield. Because metal halide perovskite nanocrystals, which are synthesized from precursor solutions, exhibit high crystallinity, research on high-resolution patterning has become popular owing to its cost-effectiveness and convenience for large-area processing. Various solution-based fabrication techniques, including lithographic approaches, electrospinning methods, and inkjet printing, have been employed to realize perovskite micropatterns for display applications. However, achieving high-resolution, transparent, and stable micropatterns in a time- and cost-effective manner remains challenging. Herein, we propose a cost-effective one-step electrohydrodynamic (EHD) jet-printing process for high-resolution, transparent, flexible, and stable methylammonium lead bromide/polyacrylonitrile (MAPbBr3/PAN) composite patterns and its surface nanomorphology control. We optimized the printing ink and processing conditions to not only generate a stable EHD jet but also ensure excellent optoelectronic properties of the MAPbBr3/PAN composite patterns. We parametrically observed its surface nanomorphology change from a nanoporous structure to a dense flat surface with the fabrication temperature. The MAPbBr3/PAN composite patterns fabricated under optimum conditions showed a high resolution of approximately 10 μm with high crystallinity, a high transmittance above 95% at visible wavelengths, and high stability under water for more than 20 days. The stability against water was attributed to the dense morphology formed at a processing temperature of 80 °C. In addition, the MAPbBr3/PAN composite patterns withstood 30,000 bending cycles with a 2 mm bending radius and 2% strain without a decrease in the photoluminescence intensity. The proposed EHD printing technique may open up intriguing possibilities for the fabrication of water-stable, transparent, and flexible display applications using metal halide perovskite nanocrystals.
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