- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Process for fabricating microactuator membranes of piezoelectric inkjet print head using multi-step deep reactive ion etching process
摘要： As part of an effort to develop piezoelectric inkjet print head (PIPH), a process for fabricating its Si-cups and actuator membranes of multi-layered structures was investigated. The manufacture of this device was enabled by the use of deep reactive ion etching (DRIE). Based on that, multi-step DRIE process was proposed to etch the multi-layered actuator membranes on silicon on insulator wafers. Due to the appropriate parameters of the etching process, undesirable effects, such as Si grasses, notching effect of Si-cups and the bowing formation on the sidewalls, were also avoided. The way to eliminate the over-etching of SiO2 membranes by controlling the appropriate platen power and process duration simultaneously was also presented. High quality PIPH actuator membranes were ?nally obtained, making great contributes to the successful inkjet test.
关键词： multi-layered actuator membranes,deep reactive ion etching,piezoelectric inkjet print head,silicon on insulator wafers,over-etching
更新于2025-09-23 15:21:21
-
A New Approach to Guided Wave Ray Tomography for Temperature-Robust Damage Detection Using Piezoelectric Sensors
摘要： In this paper, a new approach to guided wave ray tomography for temperature-robust damage detection with time-of-flight (TOF) temperature compensation is developed. Based on the linear relationship between the TOF of a guided wave and temperature, analyses show that the TOF of the baseline signal can be compensated by the temperature measurement of the inspected materials without estimating the temperature compensation parameters. The inversion is based on the optimization of the TOF misfit function between the inspected and compensated baseline TOFs of the guided waves, and is applied by the elastic net penalty approach to perform thickness change mapping in a structural health monitoring (SHM) application. Experiments that are conducted in isotropic plates by piezoelectric sensors demonstrate the effectiveness of the proposed method. According to the results, our approach not only eliminates the artefacts that are caused by a temperature variation from 25 ?C to 70 ?C but also provides more accurate and clearer imaging of damage than conventional ray tomography methods.
关键词： TOF,ray tomography,piezoelectric sensors,guided wave,structural health monitoring,temperature compensation
更新于2025-09-23 15:21:21
-
Eco-friendly highly sensitive transducers based on a new KNN-NTK-FM lead-free piezoelectric ceramic for high-frequency biomedical ultrasonic imaging applications
摘要： High-frequency ultrasonic imaging with improved spatial resolution has gained increasing attention in the field of biomedical imaging. Sensitivity of transducers plays a pivotal role in determining ultrasonic image quality. Conventional ultrasonic transducers are mostly made from lead-based piezoelectric materials that may be harmful to the human body and the environment. In this study, a new (K,Na)NbO3-KTiNbO5-BaZrO3-Fe2O3-MgO (KNN-NTK-FM) lead-free piezoelectric ceramic was utilized in developing eco-friendly transducers for high-frequency biomedical ultrasonic imaging applications. A needle transducer with a small active aperture size of 0.45 × 0.55 mm2 was designed and evaluated. The transducer exhibits great performance with a high center frequency (52.6 MHz), a good electromechanical coupling (keff ~ 0.45), a large bandwidth (64.4% at -6 dB), and a very low two-way insertion loss (10.1 dB). Such high sensitivity is superior to those transducers based on other lead-free piezoelectric materials and can even be comparable to the lead-based ones. Imaging performance of the KNN-NTK-FM needle transducer was analyzed by imaging a wire phantom and an agar tissue-mimicking phantom. Imaging capabilities of the transducer were further demonstrated by ex vivo imaging studies on a porcine eyeball and a rabbit aorta. The results suggest that the KNN-NTK-FM piezoceramic has many attractive properties over other lead-free piezoelectric materials in developing eco-friendly highly sensitive transducers for high-frequency biomedical ultrasonic imaging applications.
关键词： lead-free piezoelectric ceramic,Biomedical ultrasonic imaging,high-frequency ultrasonic transducer,eco-friendly
更新于2025-09-23 15:21:21
-
Novel Ag2O nanoparticles modified MoS2 nanoflowers for piezoelectric-assisted full solar spectrum photocatalysis
摘要： The separation of photoinduced electrons and holes can enhance the photocatalytic properties of photocatalysts. A piezoelectric field is created inside piezoelectric materials, such as ZnO and MoS2, by applying strain. The electrons and holes become separated under the driving force of the piezoelectric field. Here, we propose combining piezoelectric MoS2 nanoflowers (NFs) and full solar response Ag2O nanoparticles (NPs) to form a MoS2@Ag2O heterostructure and achieve high efficiency full solar (UV, visible, and near-infrared) photocatalysis. Under both full solar light and ultrasonic excitation, the MoS2@Ag2O heterostructures can rapidly degrade methyl orange (MO) in aqueous solution. A built-in electric field is formed by the spontaneous polarization potential of the MoS2 NFs during this process, and an ultrasonic wave as a driving force can consecutively change the potential created by the piezoelectric effect. Under light irradiation, electrons and holes are generated in the Ag2O NPs, and the photogenerated electrons and holes with opposite signs in the two Ag2O NPs at the two surfaces of the MoS2 NFs, can be separated respectively, along the spontaneous polarized direction. Therefore, the piezoelectric effect-induced enhancement of carrier separation under ultrasonic excitation can improve the full solar photocatalytic performance of the MoS2@Ag2O heterostructures.
关键词： Piezoelectric,MoS2 nanoflowers,Full solar light,Photocatalytic,Ag2O nanoparticles
更新于2025-09-23 15:21:21
-
Piezoelectric Micro- and Nanostructured Fibers Fabricated from Thermoplastic Nanocomposites Using a Fiber Drawing Technique: Comparative Study and Potential Applications
摘要： We report an all-polymer flexible piezoelectric fiber that uses both judiciously chosen geometry and advanced materials in order to enhance the piezoelectric response. The fiber features a soft hollow microstructured/nanostructured polycarbonate core surrounded with a spiral multilayer cladding consisting of alternating layers of piezoelectric nanocomposites and conductive polymer. Kilometer-long piezoelectric fibers of submillimeter diameters are thermally drawn from macroscopic preforms. The fibers exhibit high output voltage of up to 6V under moderate bending, and they show excellent durability in a cyclic test. The micron/nano-size multilayer structure enhances in-fiber poling efficiency thanks to the small distance between the conducting electrodes sandwiching the piezoelectric composite layers. Additionally, spiral structure greatly increases the active area of piezoelectric composites, thus promoting higher voltage generation and resulting in 10-100 higher power generation efficiency over the existing piezoelectric cables. Finally, we weave the piezoelectric fibers into technical textiles and demonstrate their potential applications in power generation.
关键词： nanocomposites,textiles,fiber,energy harvesting,piezoelectric
更新于2025-09-23 15:21:21
-
Prediction of Strong Piezoelectricity in 3R-MoS2 Multilayer Structures
摘要： We present the first calculation of piezoelectric constants of 3R-MoS2 which is one of three known polytypes of MoS2. We demonstrate that the 3R-MoS2 structure with 5 layers has the highest reported piezoelectric constant of all MoS2 multilayer structures. The maximum piezoelectric constant is approximately 13% above the monolayer value. Also 3R-MoS2 structures with 4 and 6 layers have a larger piezoelectric coefficient compared to monolayer MoS2. Results are obtained using the molecular dynamics computational package LAMMPS subject to room temperature simulations. Our results indicate strong potential for multilayer 3R-MoS2 structures in nanosensor and nanogenerator applications.
关键词： Piezoelectric coefficient,3R-MoS2,Multilayers,Molecular dynamics
更新于2025-09-23 15:21:21
-
Unexpectedly High Piezoelectricity of Electrospun Polyacrylonitrile Nanofiber Membranes
摘要： Polyvinylidene fluoride (PVDF) and its co-polymers are among the best piezoelectric polymer materials owing to the large piezoelectric coefficient and mechanical properties. Processing PVDF polymers into fibrous membranes through electrospinning can largely increase the piezoelectricity. In contrast, polyacrylonitrile (PAN), an amorphous polymer, is known to have a much lower piezoelectricity than PVDF. Herein, we report an unusually-high piezoelectric feature of electrospun PAN nanofiber membranes. When a small piece of PAN nanofiber nonwoven membrane (e.g. 5 cm2) was subjected to compressive impact, it can generate up to 2.0 V of voltage, the electrical outputs of which are even higher than that of PVDF nanofiber membranes at the same condition. Such unexpected piezoelectric properties were found to originate from the high content of planar Sawtooth PAN conformation within nanofibers. Electric charges in PAN nanofibers also contributed to the energy conversion. The energy conversion capability can be further enhanced by increasing fiber orientation within fibrous membrane. Also, the working area and thickness of nanofibrous membranes as well as impact conditions influenced piezoelectric outputs. The energy generated is usable and can power commercial LEDs. These unexpected discovery may inspire to develop novel piezoelectric materials and devices.
关键词： polyacrylonitrile,Piezoelectric,electrospinning,nanofibers
更新于2025-09-23 15:21:21
-
Natural Sugar Assisted Chemically Reinforced Highly Durable Piezo-Organic Nanogenerator with Superior Power Density for Self-Powered Wearable Electronics
摘要： Natural piezoelectric material is of increasing interest particularly for applications in biocompatible, implantable, and flexible electronic devices. In this paper we introduce a cost effective, easily available natural piezoelectric material, i.e., sugar in the field of wearable piezoelectric nanogenerator (PNG) where low electrical output, biocompatibility and performance durability are still critical issues. We report on a high performance piezo-organic nanogenerator (PONG) based on the hybridization of sugar encapsulated polyvinylidene fluoride (PVDF) nanofiber webs (SGNFW). We explore the crucial role of single crystal sugar having fascinating structure along with the synergistic enhancement of piezoelectricity during nano-confinement of sugar interfaced macromolecular PVDF chains. As a consequence, the SGNFW based PONG exhibits outstanding electricity generation capability (for example ~100V under 10 kPa human finger impact and maximum power density of 33 mW/m2) in combination with sensitivity to abundantly available different mechanical sources (such as wind flow, vibration, personal electronics and acoustic vibration). Consequently, it opens up suitability in multifunctional self-powered wearable sensor designs for realistic implementation. In addition, commercially available capacitors are charged up effectively by the PONG due to its rapid energy storage capability. The high performance or the PONG not only offers the “battery free” energy generation (several portable units of LEDs and a LCD screen are powered up without using external storage) but also promises its use in wireless signal transmitting systems that widens the potential in personal health care monitoring. Furthermore, owing to the geometrical stress confinement effect, the PONG is proven to be a highly durable power generating device validated by stability test over 10 weeks. Therefore, the organic nanogenerator would be a convenient solution for portable personal electronic devices that are expected to operate in a self-powered manner.
关键词： self-powered electronics,PVDF,organic piezoelectric nanogenerator,high performance and durability,Natural piezoelectric material,sugar
更新于2025-09-23 15:21:01
-
Improved upconversion photoluminescence properties of 0.965K0.4Na0.58Li0.02Nb0.96Sb0.04O3–0.035Bi0.5K0.5ZrO3:0.25%Er/xIn lead-free piezoelectric ceramics with balanced piezoelectric coefficient and Curie temperature
摘要： A series of erbium- and indium-doped 0.965K0.40Na0.58Li0.02Nb0.96Sb0.04O3–0.035Bi0.5K0.5ZrO3:0.25%Er/xIn lead-free piezoelectric ceramics with upconversion photoluminescence (UCPL) properties were prepared by the conventional solid state reaction. A systematical investigation into the effects of In3+ doping on the structural, dielectric, ferroelectric, piezoelectric, and UCPL properties of the ceramics was carried out. The distribution of Er3+-sites could be modified by In3+ doping according to the analysis of UV–Vis-NIR absorption cross-section, resulting in improved piezoelectric and photoluminescence properties of the ceramics. The optimized comprehensive properties are performed by the x = 0.25% samples of which the piezoelectric coefficient d33 ~ 257 pC/N, Curie temperature TC ~ 273 °C, remanent polarization Pr ~ 12.5 μC/cm2, dielectric constant εr ~ 1551, and d33 ~ 257 pC/N which is the supreme piezoelectric coefficient achieved in KNN-based UCPL ceramics as of now. The results demonstrate that erbium and indium co-doped KNN-based ceramics may have potential applications in electro-optical devices.
关键词： Upconversion photoluminescence,Erbium and indium co-doping,Piezoelectric coefficient,Lead-free piezoelectric ceramics,Curie temperature
更新于2025-09-23 15:21:01
-
Controlled-Atmosphere Sintering of KNbO3
摘要： The e?ect of sintering atmosphere (O2, air, N2, N2-5% H2, and H2) on the densi?cation, grain growth, and structure of KNbO3 was studied. KNbO3 powder was prepared by solid state reaction, and samples were sintered at 1040 C for 1–10 h. The sample microstructure was studied using Scanning Electron Microscopy (SEM). The sample structure was studied using X-Ray Di?raction (XRD). H2-sintered samples showed reduced density, whereas other sintering atmospheres did not a?ect density much. Samples sintered in N2-5% H2 showed abnormal grain growth, whereas sintering in other atmospheres caused stagnant (O2, air, N2) or pseudo-normal (H2) grain growth behavior. Samples sintered in reducing atmospheres showed decreased orthorhombic unit cell distortion. The grain growth behavior was explained by the mixed control theory. An increase in vacancy concentration caused by sintering in reducing atmospheres led to a decrease in the step free energy and the critical driving force for appreciable grain growth. This caused grain growth behavior to change from stagnant to abnormal and eventually pseudo-normal.
关键词： lead-free piezoelectric,microstructure grain growth,alkali niobate
更新于2025-09-23 15:21:01