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323 results on '"Geng, Wenping"'

61. Electromagnetic Energy Harvester Based on Bidirectional Vibration to Unidirectional Rotation Conversion for Environmental Low-Frequency Vibration Energy Harvesting

Author

Hou, Xiaojuan, Niu, Lixin, Qian, Shuo, Hu, Dongxu, Hou, Jianwei, Shi, Shuzheng, Geng, Wenping, He, Jian, and Chou, Xiujian

Abstract

Harvesting low-frequency vibration energy in the environment can provide electrical energy for mobile electronic devices. In this article, a bidirectional driving vibration energy harvester is presented based on the electromagnetic induction. The bidirectional driving component of the energy harvester converts the reciprocating linear motion driving energy into the unidirectional rotation. In addition, the two sets of generators are rectified first, and then connected in series to reduce the voltage rang, which is conducive to energy management and storage, and reduces energy loss. The results show that its average output power is 53.28 mW when the acceleration is 9 m/s2. At a running speed of 8 km/h, the average output power of the energy harvester installed on the human torso is 41.07 mW. At the same time, it can provide real-time energy supply for temperature hygrometer, calculator, and Bluetooth module. It is a novel method for the harvest and utilization of vibration energy, and has great significance for solving the current energy long-term demand of electronic devices.

Published
2024
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63. Electric-Force Conversion Performance of Si-Based LiNbO 3 Devices Based on Four Cantilever Beams.

Author

Zhang, Huiyi, Qiao, Xiaojun, Wei, Huifen, Li, Xiaohuang, Wu, Xiaohui, Yu, Nanxin, Lu, Hao, Guo, Tao, Chou, Xiujian, and Geng, Wenping

Subjects
PIEZOELECTRICITY, CANTILEVERS, LITHIUM niobate, PIEZOELECTRIC devices, SMART devices, SMART structures, PIEZOELECTRIC transducers
Abstract

In micron or nano smart sensing systems, piezoelectric cantilever beams are distributed as major components in microsensors, actuators, and energy harvesters. This paper investigates the performance of four cantilever beam devices with "electric-force" conversion based on the inverse piezoelectric effect of lithium niobate (LiNbO3, LN) single-crystal materials. A new compact piezoelectric smart device model is proposed, designed as a single mass block connected by four beams, where devices exhibit smaller lateral errors (0.39–0.41%). The relationship between the displacement characteristics of cantilever beams and driving voltage was researched by applying excitation signals. The results show that the device has the maximum displacement at a first-order intrinsic frequency (fosc = 11.338 kHz), while the displacement shows a good linear relationship (R2 = 0.998) with driving voltage. The square wave signals of the same amplitude have greater "electrical-force" conversion efficiency. The output displacement can reach 12 nm, which is much higher than the output displacement with sinusoidal excitation. In addition, the relative displacement deviation of devices can be maintained within ±1% under multiple cycles of electrical signal loading. The small size, high reliability, and ultra-stability of Si–LN ferroelectric single-crystal cantilever beam devices with lower vibration amplitudes are promising for nanopositioning techniques in microscopy, diagnostics, and high-precision manufacturing applications. [ABSTRACT FROM AUTHOR]

Published
2023
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64. Multifunctionality in (K,Na)NbO3-based ceramic near polymorphic phase boundary.

Author

Wang, Xiangjian, Lou, Xiaojie, Geng, Wenping, Yao, Yingbang, Tao, Tao, Liang, Bo, and Lu, Sheng-Guo

Subjects
ENERGY storage, ELECTRONIC equipment, CERAMICS, ELECTRIC fields, THERMAL stability
Abstract

The 0.95K0.42Na0.58Nb0.96Sb0.04O3–0.02BaZrO3–0.03Bi0.5K0.5HfO3 ceramic was fabricated via a conventional solid-state reaction. This ceramic exhibits the diffuse polymorphic phase boundary (PPB) near room temperature. The dielectric, ferroelectric, electromechanical, electrocaloric, and dielectric energy storage properties were studied systemically. The normalized large signal d33* values are approximately 400–600 pm/V at measured temperatures and electric fields, which are larger than or comparable with the values reported in other lead-free compositions. The electrocaloric strength is enhanced at the broad region of PPB provided by the indirect and direct measurements. At low field of 30 kV/cm, the dielectric energy storage is ∼0.12–018 J/cm3 at relative broad temperature range due to the diffuse nature of polymorphic phase boundary. Theoretical simulations reveal that multi-element dopants, such as Sb5+, Hf4+, Zr4+, and Bi3+ ions, could induce the breaking of local structure symmetry in the orthorhombic phase to form the PPB. In addition, the charge distribution may also break the long-range ferroelectric order through the analysis of Bader charge. Our study suggests that the K0.5Na0.5NbO3-based ceramic exhibits improved performance and good thermal stability in piezoelectric, electrocaloric, and dielectric energy storage characteristics in terms of the design of multi-element dopants to form the PPB and it will benefit the promising applications in electronic devices. [ABSTRACT FROM AUTHOR]

Published
2021
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78. Patterned Graphene-Based Metamaterials for Terahertz Wave Absorption

Author

Zhou, Siyuan, primary, Bi, Kaixi, additional, Li, Qiannan, additional, Mei, Linyu, additional, Niu, Yaokai, additional, Fu, Wenxiao, additional, Han, Shuqi, additional, Zhang, Shuai, additional, Mu, Jiliang, additional, Tan, Ligang, additional, Geng, Wenping, additional, and Chou, Xiujian, additional

Published
2022
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88. Synergistic piezoelectricity enhanced BaTiO3/polyacrylonitrile elastomer-based highly sensitive pressure sensor for intelligent sensing and posture recognition applications.

Author

Yu, Junbin, Xian, Shuai, Zhang, Zhenpeng, Hou, Xiaojuan, He, Jian, Mu, Jiliang, Geng, Wenping, Qiao, Xiaojun, Zhang, Le, and Chou, Xiujian

Abstract

Designing stretchable and skin-conformal self-powered sensors for intelligent sensing and posture recognition is challenging. Here, based on a multi-force mixing and vulcanization process, as well as synergistically piezoelectricity of BaTiO3 and polyacrylonitrile, an all-in-one, stretchable, and self-powered elastomer-based piezo-pressure sensor (ASPS) with high sensitivity is reported. The ASPS presents excellent sensitivity (0.93 V/104 Pa of voltage and 4.92 nA/104 Pa of current at a pressure of 10–200 kPa) and high durability (over 10,000 cycles). Moreover, the ASPS exhibits a wide measurement range, good linearity, rapid response time, and stable frequency response. All components were fabricated using silicone, affording satisfactory skin-conformality for sensing postures. Through cooperation with a homemade circuit and artificial intelligence algorithm, an information processing strategy was proposed to realize intelligent sensing and recognition. The home-made circuit achieves the acquisition and wireless transmission of ASPS signals (transmission distance up to 50 m), and the algorithm realizes the classification and identification of ASPS signals (accuracy up to 99.5%). This study proposes not only a novel fabrication method for developing self-powered sensors, but also a new information processing strategy for intelligent sensing and recognition, which offers significant application potential in human—machine interaction, physiological analysis, and medical research. [ABSTRACT FROM AUTHOR]

Published
2023
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99. Patterned Graphene-Based Metamaterials for Terahertz Wave Absorption.

Author

Zhou, Siyuan, Bi, Kaixi, Li, Qiannan, Mei, Linyu, Niu, Yaokai, Fu, Wenxiao, Han, Shuqi, Zhang, Shuai, Mu, Jiliang, Tan, Ligang, Geng, Wenping, and Chou, Xiujian

Subjects
SUBMILLIMETER waves, TERAHERTZ materials, METAMATERIALS, MANUFACTURING processes, OPTICAL modulators, CHEMICAL detectors, OPTOELECTRONIC devices, OPTICAL sensors, TERAHERTZ spectroscopy
Abstract

Graphene-based metamaterials have been widely applied in optoelectronic devices, optical modulators, and chemical sensors due to the outstanding tunability and optical response in the terahertz (THz) region. Here, tunable THz metamaterial absorbers based on patterned graphene are designed, fabricated, and modulated. The proposed metamaterial absorbers are constructed by the top layer of patterned graphene arrays and the aluminum (Al) film separated by polyimide (PI). The different THz absorption spectra can be acquired by changing the patterns of graphene. In order to verify the simulation results, a series of tests were conducted by THz time-domain spectrometer (THz-TDS) systems. The proposed absorbers are able to be insensitive to the angle of the incident wave. Besides, chemical doping is applied to turn the Fermi level of graphene and the absorption performance is promoted with the increase of the Fermi level. The experimental results have been demonstrated to have associated resonant peaks with the simulation results. The aim of this paper is to exhibit a systematic study on graphene-based THz metamaterial absorbers, including the simulation and experiments. By comparing the simulation and experimental results, it is useful to clarify the relevant theories and manufacturing processes. The work will provide a further step in the development of high-performance terahertz devices, including tunable absorbers, sensors, and electro-optic switches. [ABSTRACT FROM AUTHOR]

Published
2023
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