驻极体声传感器及其储电材料的现状

综述了驻极体声传感器及其储电材料近年来的迅猛发展。传统的FEP(tetrafluoroethylene—hexa—fluoropropylene copolymer)极体电容式声传感器及以铁电聚合物PVDF(poly vinylidene fluoride)家族为芯片的声传感器和超声抉能器仍焕发着青春活力。Si基微型驻极体声传感器的理论和实验研究已经日趋成熟，而用空间电荷型多孔聚合物驻极体压电薄膜为芯片可望研制出新一代声电和电声传感器、压力传感器和驱动器。     

P/C柔性复合压电薄膜通过技术鉴定

现代电子功能材料与器件学科的一个新型领域——柔性复合压电功能薄膜,于1991年12月29日在电子科技大学通过技术成果鉴定。 P/C柔性复合压电薄膜系PVDF基压电聚合物与铁电陶瓷PZT等3—0型柔性复合压电PVDF/PZT薄膜系列,具有兼顾优异机械韧性与高度综合压电特性,柔韧性(C_33<9N/m~2柔韧强度),耐震抗冲击、紧触检测灵敏性,可塑加工性(大面积成膜、     

聚偏氟乙烯结晶结构及其β相制备方法的研究

聚偏氟乙烯(PVDF)聚合物因为具有优良的铁电、压电和热释电性能而受到广泛研究.该文结合近期国内外有关PVDF研究的相关论文报道,综述了与PVDF聚合物相结构有关的研究进展,着重介绍了PVDF形成的5种晶型的分子结构及不同晶型间的差别、晶型之间相互转化机理的有关内容;同时,总结了近期在制备或提高PVDF中β相含量研究中的若干新方法、新思路及它们各自的利弊,并对今后的相关研究进行了展望.     

PVDF压电薄膜的性能优化研究进展

聚偏氟乙烯(PVDF)压电薄膜是一种压电高分子材料,具有广泛的科学价值和技术应用前景。PVDF薄膜因具有独特的压电效应,且质地软,灵敏度高及频响范围宽等优点,使其在能量收集、新型智能传感器、生物医学、电池隔膜等领域得到了广泛的应用和关注。PVDF晶区中至少有4种晶型,其中β晶型PVDF具有优异的压电性能。该文总结了近年来通过制备工艺、化学掺杂及改性方法的优化来提高β晶型含量,进而提升薄膜性能的方法,系统地介绍了PVDF压电薄膜在部分领域的应用,并对其未来发展做出了展望。     

聚丙烯压电驻极体薄膜声电传感器的性能

压电驻极体（也称为铁电驻极体）是以空间电荷驻极体为基体的一类新型压电功能材料,这种材料不仅具有与压电陶瓷相近的压电活性,同时拥有柔韧、低介电常数和低声阻抗等特点。本研究制备了基于聚丙烯（PP）压电驻极体薄膜的声电传感器,并采用电压放大电路和电荷放大电路对其在声频下的灵敏度进行了测量。结果表明,PP压电驻极体声电传感器在1 kHz下的电压灵敏度约为0.8 mV/Pa,并在300 Hz~10 kHz的声频范围内有良好的线性输出特性。     

钛酸盐系铁电薄膜和它们的应用(一)

钛酸盐系铁电材料多具有高介电常数和优良的压电性能,以往人们多着重研究和应用这些效应,但随着技术的发展对铁电材料的电光、声光、热电等效应逐步和加深了认识,如何充分利用铁电材料多功能效应研制在新技术发展中极感兴趣的各种新型功能(或多功能)器件引起了极大的重视,但遗憾的是应用固态材料的多功能效应往往受到很多技术上的限制,诸如要高的电压驱动,难以获得均匀的大面积块体,也难于实现近代电子器件的高集成化等等要求,而薄膜技术的发展为充分利用铁电材料的多功能效应创造了有利条件。诚然,要求生长出的铁电薄膜达到实用化仍有不少问题,但近几年来在铁电、压电薄膜材料研究方面巳做了大量工作,主要在以下几个方面     

压电及其它功能器件

３压电及其它功能器件９５０２８压电聚合物膜水听器频响的理论分析─—ＮａｋａｍｎｒａＹ．ＪＡｃｏｉｉｓｔＳｏｒＪｐｎ１９９３；４９（１０）：６９７～７０４从数字上分析了圆接收面和衬底材料为圆筒状的压电聚合物膜水听器的频率响应，由于水听器衬底材料上感生的...     

电声传感聚合物驻极体发展的新动态

驻极体薄膜作为电声传感器件应用已有几十年的历史，近年来国际上对多孔驻极体材料的压电效应引起了业内人士的高度重视和极大兴趣。聚合物薄膜压电传感嚣随着新型薄膜材料的发展而有可能成为未来驻极体应用的一个高层次的领域和更新换代的产品。     

串联2—2复合材料的介电击穿研究

研究了串联2－2型复合材料的介电击穿特性。串联2－2型压电复合材料结构较为简单，它是研究具有复杂连通性压电复合材料的基础。根据能量守恒定律，推导出串联2－2复合材料中压电陶瓷PZT层上和聚合物PVDF层上的电场强度Ec、Ep。由于压电陶瓷的介电常数εc(≈1600ε0)远远大于聚合物的介电常数εp(≈12εo)，因此Ep远远大于Ec。尽管PVDF的介电强度高于PZT的介电强度，但由于Ep远远大于Ec，所以串联2－2型压电复合材料的介电击穿往往是从聚合物层开始的，最后导致复合材料整体被击穿。对理论计算进行了实验验证，结果表明：在PZT含量较低时，计算值与试验值比较接近，但随着复合材料中PZT含量的提高，二者的偏差越来越大。文章最后定性讨论了在高PZT含量时复合材料的计算值与试验值偏差较大的原因。     

聚偏氟乙烯压电薄膜的应用及国内发展动态

聚偏氟乙烯压电薄膜的应用及国内发展动态吴琼近年来，在压电功能材料中，有机压电材料发展得很快，特别是聚偏氟乙烯（ＰＶＯＦ）压电薄膜发展得尤为迅速，投放市场后倍受青睐。ＰＶＤＦ压电薄膜是一种具有良好的压电性能的高分子聚合物，它是一种以－ＣＨ＿２－ＣＦ＿２...     

Piezoelectric sensor based on electrospun PVDF-MWCNT-Cloisite 30B hybrid nanocomposites

Piezoelectric materials have attracted substantial interest in applications such as sensors and actuators. Ferroelectric and piezoelectric polymeric fibers doped with nanoparticles are made for use in nanoscale electronic devices. In this paper, we report on poly (vinylidene fluoride) (PVDF) nanocomposites doped with different ratios of multi-walled carbon nanotube (MWCNT) and Cloisite 30B (OMMT) nanoclay prepared by electrospinning technique. The effect of different ratios of OMMT and MWCNT nanofillers and potential synergistic effect of these fillers on the crystalline structure of PVDF and the performance of resulting piezo-device were studied. Results showed that OMMT increases beta phase crystals and piezoelectric properties of PVDF as compared with MWCNT. Meanwhile, MWCNT decreases impedance and increases dielectric constant of PVDF as compared with OMMT. The acoustic absorption behavior of PVDF/MWCNT/OMMT hybrid nanocomposite was also investigated. It was found that the sound absorption efficiency of PVDF/MWCNT/OMMT hybrid nanocomposites was increased compared with that of pure PVDF fibers and film. No synergistic effect of OMMT and MWCNT on the properties of PVDF was observed.     

Recent Progress on Structure Manipulation of Poly(vinylidene fluoride)-Based Ferroelectric Polymers for Enhanced Piezoelectricity and Applications

Poly(vinylidene fluoride) (PVDF)-based polymers demonstrate great potential for applications in flexible and wearable electronics but show low piezoelectric coefficients (e.g., −d₃₃ < 30 pC N⁻¹). The effective improvement for the piezoelectricity of PVDF is achieved by manipulating its semicrystalline structures. However, there is still a debate about which component is the primary contributor to piezoelectricity. Therefore, current methods to improve the piezoelectricity of PVDF can be classified into modulations of the amorphous phase, the crystalline region, and the crystalline–amorphous interface. Here, the basic principles and measurements of piezoelectric coefficients for soft polymers are first discussed. Then, three different categories of structural modulations are reviewed. In each category, the physical understanding and strategies to improve the piezoelectric performance of PVDF are discussed. In particular, the crucial role of the oriented amorphous fraction at the crystalline–amorphous interface in determining the piezoelectricity of PVDF is emphasized. At last, the future development of high performance piezoelectric polymers is outlooked.     

聚偏氟乙烯压电膜在医疗仪器中的应用

聚偏氟乙烯压电材料是近年来应用十分广泛的换能材料，可应用于电声器材，医疗仪器，机器人用传感器，超声波的发生与检测等领域，本文介绍了聚偏氟乙烯压电膜在医疗仪器领域中应用的最新进展，并列举了实例。     

Printable,Transparent, and Flexible Touch Panels Working in Sunlight and Moist Environments

The ongoing revolution of touch‐based user interfaces sets new requirements for touch panel technologies, including the need to operate in a wide range of environments. Such touch panels need to endure moisture and sunlight. Moreover, they often need to be curved or flexible. Thus, there is a need for new technologies suitable, for example, for home appliances used in the kitchen or the bathroom, automotive applications, and e‐paper. In this work, the development of transparent and flexible touch panels for moist environments is reported. A piezoelectric polymer, poly(vinylidene difluoride) (PVDF), is used as a functional substrate material. Transparent electrodes are fabricated on both sides of a PVDF film using a graphene‐based ink and spray coating. The excellent performance of the touch panels is demonstrated in moist and underwater conditions. Also, the transparent device shows very small pyroelectric response to radiative heating in comparison to a non‐transparent device. Solution processable electrode materials in combination with functional substrates allow the low‐cost and high‐throughput manufacturing of touch panels using printing technologies.     

Theoretical Model and Outstanding Performance from Constructive Piezoelectric and Triboelectric Mechanism in Electrospun PVDF Fiber Film

Flexible materials with high electromechanical coupling performance are highly demanded for wide applications for electromechanical sensors and transducers, including mechanical energy harvesters. Here, outstanding electromechanical performance is obtained in electrospun‐aligned polyvinylidene fluoride (PVDF) fiber film. A theoretical model is developed from systematic theoretical analyses to clarify the underlying constructive piezoelectric‐triboelectric mechanism in the polarized PVDF fiber films that explains the experimental observations well. The electrospinning process induces polarization alignment and thus tunes the electron affinity for PVDF fibers with different polarization terminals, which results in the constructive piezoelectric and triboelectric responses in the obtained PVDF fiber films. Extremely large effective piezoelectric performance properties are achieved in the direct piezoelectric measurements, reaching the maximum effective piezoelectric strain and voltage coefficients of ?1065 pm V^?1 and ?9178 V mm N^?1, respectively, at 100 Hz. In the converse piezoelectric measurements without a significant contribution from reversible triboelectric effect, the maximum effective piezoelectric strain and voltage coefficients are ?166 pm V^?1 and ?1499 V mm N^?1, respectively. The theoretical analyses and experimental results show the great potential of the electrospun aligned polar PVDF fiber material for various electromechanical device applications, particularly for mechanical energy harvesting.     

PVDF传感器的设计及在振动测量中的应用

聚偏氟乙烯(PVDF)是一种新型压电高分子材料，它具有独特的压电效应，近年来广泛用于振动控制领域。文中通过设计正弦和余弦形状PVDF传感器，用于测量振动参数。并以测量一维悬臂梁的位移和功率流为例进行了证实，结果表明PVDF传感器测量更方便、应用更广泛，因此可在振动参数的测量中加以推广。     

On low-frequency electric power generation with PZT ceramics

Piezoelectric materials have long been used as sensors and actuators, however their use as electrical generators is less established. A piezoelectric power generator has great potential for some remote applications such as in vivo sensors, embedded MEMS devices, and distributed networking. Such materials are capable of converting mechanical energy into electrical energy, but developing piezoelectric generators is challenging because of their poor source characteristics (high voltage, low current, high impedance) and relatively low power output. In the past these challenges have limited the development and application of piezoelectric generators, but the recent advent of extremely low power electrical and mechanical devices (e.g., MEMS) make such generators attractive. This paper presents a theoretical analysis of piezoelectric power generation that is verified with simulation and experimental results. Several important considerations in designing such generators are explored, including parameter identification, load matching, form factors, efficiency, longevity, energy conversion and energy storage. Finally, an application of this analysis is presented where electrical energy is generated inside a prototype Total Knee Replacement (TKR) implant.     

A study on PVDF sensor using wireless experimental system for bridge structural local monitoring

Originated from aerospace area, smart material structures have been a research hotspot in the application of engineering. For structural health monitoring within the context of civil engineering, the research about high-performance sensing units are very important. As one of the piezoelectric materials belonging to smart ones, Polyvinylidene Fluoride (PVDF) is widely regarded for its property advantages of low cost, good mechanical abilities, high sensibility, and corrosion resistance. In this paper, for the validation of PVDF sensors as sensing units for bridge structural local monitoring, wireless experimental systems of PVDF sensor for structural local monitoring on a bridge model and beam were built. Firstly, based on the operating mechanism, the measurement circuit and the characteristics of PVDF are introduced. Secondly, system framework of PVDF sensor for local monitoring is proposed, a bridge model is built, wireless sensor kits are then developed. Finally, Bridge damage monitoring experiments have been done for structural local health monitoring using PVDF sensors. The experimental results show that PVDF sensor can handle structural impact response monitoring and damage detection of civil engineering, and the developed wireless sensor experimental system can be easily implemented for use in practical monitoring engineering.     

PVDF薄膜传感器前置放大模块设计及实验研究

聚偏二氟乙烯(PVDF)压电薄膜具有良好的压电效应,被广泛应用于振动测量等领域。该文通过分析PVDF压电薄膜的电路模型,设计了与之配套的前置放大模块,并对该模块进行了理论分析和实验测试,测试结果与理论相符。应用PVDF薄膜配合设计的前置放大模块对圆管内流场信息进行了对比试验。试验结果表明,PVDF压电薄膜对于管内流场的测量在低频区域优于加速度计,可测量到丰富的低频成分,为分析管内的流场信息提供了良好的实验基础。