静电纺压电纳米纤维膜在声电转换器件中的应用研究

发布时间：2017-12-26 23:18

本文关键词：静电纺压电纳米纤维膜在声电转换器件中的应用研究　出处：《东华大学》2017年博士论文　论文类型：学位论文

【摘要】：声电转换器件按照应用领域不同主要分为检测记录声音的声传感器和将声能转换成可利用的电能的声发电机。在声电转换装置中,以压电效应为作用原理,以柔性压电聚合物为传感材料的压电式声传感器和声发电机以其柔韧性、易加工、易成形、可制成各种尺寸,适用于各种应用场合,耐久性好等特点得到各领域广泛的应用与研究。然而,应用于声电转换领域中的商业压电膜器件的性能并不完善,输出电压和能量均较小。此外,商业压电膜的生产工艺较为复杂,成本高,导致压电膜价格昂贵。静电纺工艺可制备具有高β晶型相对含量高压电性的PVDF及P(VDF-TrFE)压电纳米纤维膜。目前,对于静电纺PVDF及P(VDF-TrFE)纳米纤维的工艺的研究已经较为成熟,然而,对于静电纺PVDF及P(VDF-TrFE)纳米纤维的应用主要为压力传感器和压力或拉伸力作用下的纳米发电机,在声学领域的应用鲜有报道。本文制备了基于静电纺PVDF和P(VDF-TrFE)压电纳米纤维膜的高性能声传感器和声发电机,具体研究内容如下:(1)声电转换性能测试装置的搭建与评价体系的建立搭建声电转换性能的测试装置与信号处理方法如下:连接电脑的扬声器作为声源,声音测试软件控制声音的频率,分贝仪测试声压大小,电化学工作站采集通过电极引出的电信号,得到的信号通过快速傅里叶变换的数学方法分析信号的频域特征,并对信号进行除噪处理。声电转换性能的评价体系建立如下:声传感器的主要性能评价指标为输出电压、信噪比和灵敏度,声发电机的主要性能评价指标为最大输出电压、最大输出电流、内阻、瞬时功率、瞬时功率面密度、瞬时功率体密度、功率、能量和能量转换效率。(2)研制基于静电纺压电纳米纤维膜的高性能声传感器为了摸索高性能传感器的结构和参数,首先设计制备了声传感器雏型,即利用静电纺pvdf压电纳米纤维膜作为感芯材料,与铝箔电极及振动基底构成的声传感器件。声传感器雏形的输出信号较小,信噪比低,因此选择输出电压和输出信号的信噪比两个评价参数综合评价声传感器性能。通过探索器件的各部分参数,如振动基底材料、器件尺寸、电极材料尺寸等对器件性能的影响,对传感器的结构进行优化,得到最优的结构参数:振动基底材料为双面塑料膜;传感器的尺寸为16cm2,长宽比为1:1;电极尺寸为16cm2。分析可能导致输出信号小的原因为器件的封闭性结构,电极的选择以及器件的单支架测试固定方式。针对这几点不足,提出了相应的改进方法:在振动基底上设计通孔结构,在振动基底内层镀金代替铝箔作为电极,并采用了双支架的测试固定方式。改进后的静电纺压电纳米纤维膜声传感器性能得到很大提升,通过研究传感器振动基底的通孔尺寸、纳米纤维膜的面积和厚度、纳米纤维直径以及纳米纤维的排列状态对传感器电压输出和灵敏度的影响,优化传感器结构以及纳米纤维膜的参数。优化后的参数如下:带有通孔直径为12.8mm的pet塑料振动基底,纳米纤维膜厚度为40μm,尺寸为3cm×4cm,纳米纤维平均直径为310nm。优化参数后的声传感器性能优异,测得的最高灵敏度和电压输出分别为266mv/pa和3.10v,比相同结构的商业压电膜传感器高五倍以上,可以准确区分中低频区域的声波。同时演示了使用高性能压电纳米纤维膜声传感器记录人说话声音和播放的音乐的应用实例,得到的信号与商业麦克风记录的信号基本一致。由于纳米纤维膜传感器在声压高于100db具有较高的灵敏度,因此尤其适合用于噪音的监测。(3)基于静电纺压电纳米纤维膜的高性能声发电机通过进一步改进声传感器的结构,制备了基于p(vdf-trfe)压电纳米纤维膜的声发电机,制备的声发电机可以将声能转换成可利用的电能,研究振动基底上通孔的数量、膜的厚度和纳米纤维直径对于器件内阻、输出电压和电流的影响,优化了器件结构和纳米纤维膜的参数:8孔器件,孔直径为4.9cm,膜厚度为20μm,纳米纤维直径为240nm。优化后的声发电机件具有优异的声电能量转换性能,尤其当声压高于100db时可以输出更多的电能。器件的最大输出电压和电流分别为14.5v和28.5μa,功率体积密度为306.5μw/cm3,能量转换效率为60.3%,比商业的p(vdf-trfe)压电膜制成相同结构的器件的输出高五倍以上。器件转换的电能可以不需要使用任何能量收集装置直接用来驱动微电子器件,如点亮若干串联的led小灯泡照明,也可以用来诱发电化学反应,如驱动edot的电化学聚合和金属的阴极保护电化学防腐。这些优异的性能使得静电纺p(vdf-trfe)纳米纤维膜声发电机特别适用于将白色污染噪音转换为可利用的电能的应用场合。(4)声电转换器件在声音作用下振动的有限元模拟为了探究器件结构对于声电转换性能的影响,利用有限元建模分析软件COMSOL对器件在声音中的振动进行了模拟与计算。分别模拟计算了8孔器件和单孔器件的纳米纤维膜中心点振动,器件振动的平均速率、器件表面的振动能量、器件的整体振动能量,同时也模拟计算了塑料膜上孔之间距离对整体振动能量的影响。通过模拟计算的数据与激光振动仪测试的器件的振动情况来分析器件结构对于器件输出性能的影响机理。模拟计算的结果为在高声压作用下(100~115dB),8孔器件的纳米纤维膜和PET塑料膜的振动能量均明显高于单孔器件;而在低声压作用下(60~100dB),两者差距较小。因此在低声压时,两种器件的电能输出差别较小;在高声压时,8孔器件的能量输出明显高于单孔器件的能量输出。多孔结构起到了带动整个器件振动的效果,增加了器件吸收声能转化成自身的振动能量,从而通过压电效应将更多的机械能转化为电能输出,提高能量转换效率。
[Abstract]:In accordance with the different application fields, the acoustic transducer is divided into the sound sensor that detects and records the sound and the sound energy is converted into the available electric energy. In the acoustic electric conversion device, using piezoelectric effect principle, the flexible piezoelectric polymer sensing material piezoelectric acoustic sensor and sound generator with its flexibility, easy processing, easy forming, made of various sizes, suitable for a variety of applications, has good durability and other characteristics in various fields widely application and research the. However, the performance of the commercial piezoelectric film devices used in the field of acoustic and electrical conversion is not perfect, and the output voltage and energy are small. In addition, the production process of the commercial piezoelectric film is more complex and the cost is high, which leads to the high price of the piezoelectric film. PVDF and P (VDF-TrFE) piezoelectric nanofibrous membrane with high high pressure of high beta crystal content can be prepared by the electrospun process. At present, the electrospun PVDF and P (VDF-TrFE) technology of nano fiber has been more mature, however, the electrospun PVDF and P (VDF-TrFE) is the main application of nano fiber nano generator effect of pressure sensor and pressure or tensile force, the application is rarely reported in the field of acoustics. The preparation of electrospun PVDF and P (VDF-TrFE) based on high performance acoustic sensor and sound generator piezoelectric nano fiber membrane, the specific contents are as follows: (1) to build and establish the evaluation system of the following set up a test device and signal processing method of acoustic electric conversion properties of acoustic electric conversion performance testing device connected to the computer: the speaker as a sound source, sound control software test frequency, test pressure decibel meter size, electrochemical workstation to collect the electrical signals through the electrode leads, the frequency characteristics of the signal analysis signal through the mathematical method of fast Fu Liye transform, and the signal denoising processing. The evaluation system of sound power conversion performance is established as follows: key performance index for acoustic sensor output voltage, signal-to-noise ratio and sensitivity, key performance index for sound generator for maximum output voltage, maximum output current, internal resistance, instantaneous power, instantaneous power surface density, instantaneous power density, power, energy and energy conversion efficiency. (2) based on the development of high performance piezoelectric acoustic sensor of electrospun nanofibrous membrane in order to explore the structure and parameters of the high performance of the sensor, the first prototype design acoustic sensor was prepared by electrospinning PVDF piezoelectric nano fiber membrane as core material, acoustic sensor elements and aluminum foil electrode and substrate vibration. The output signal of the acoustic sensor is small and the signal-to-noise ratio is low. Therefore, two evaluation parameters of output voltage and signal to noise ratio of output signal are selected to evaluate the performance of acoustic sensor comprehensively. Through the parameters to explore devices, such as the impact of vibration of base material, the size of the device, the electrode material size on the performance of the device, the structure of the sensor is optimized to get the optimal structure parameters: vibration base material double-sided plastic film; the size of the sensor is 16cm2, the ratio of length to width is 1:1; the electrode size is 16cm2. The reasons for the small output signal are the closed structure of the device, the selection of the electrode and the single stent test fixed mode of the device. Aiming at these shortcomings, the corresponding improvement method is put forward: the design of the through-hole structure on the vibrating substrate, the inner layer of the vibrating base is plated with gold instead of the aluminum foil as the electrode, and a double bracket test fixing method is adopted. Electrostatic spinning improved piezoelectric acoustic sensor properties of nano fiber membrane have been greatly improved, through the arrangement of hole size, vibration sensor research base nano fiber membrane area and thickness, the diameters of nanofibers and nano fiber effect on the sensor output voltage and the sensitivity of the parameter optimization of sensor structure and nano fiber film. The optimized parameters are as follows: the pet plastic vibration substrate with a diameter of 12.8mm through the hole, the thickness of nanofiber membrane is 40 m, the size is 3cm * 4cm, and the average diameter of nanofiber is 310nm. The optimized sensor has excellent performance, and the highest sensitivity and voltage output are 266mv/pa and 3.10v, which is five times higher than that of the same commercial piezoelectric membrane sensor. It can distinguish the sound waves in the middle and low frequency region accurately. At the same time, we demonstrate the application of high performance piezoelectric nanofiber membrane acoustic sensor to record human voice and play music. The obtained signal is basically consistent with the signal recorded by commercial microphone. As the nanofiber membrane sensor has high sensitivity in sound pressure higher than 100dB, it is especially suitable for noise monitoring. (3) based on electrospun piezoelectric nano fiber membrane high performance acoustic generator by further improving the structure of acoustic sensor, were prepared based on P (VDF-TrFE) acoustic generator piezoelectric nano fiber membrane, preparation of the acoustic generator can converts sound energy into usable electrical power, influence of thickness quantity, through hole research the vibration of substrate film and nano fiber diameter on the device resistance, output voltage and current parameters, device structure and nano fiber membrane were optimized: 8 hole devices, hole diameter is 4.9cm, the film thickness is 20 m and the diameter of 240nm nanofibers. The optimized acoustic generator has excellent acoustic and electrical energy conversion performance, especially when the sound pressure is higher than 100dB, more power can be output. The maximum output voltage and current of the device are 14.5V and 28.5 a, respectively. The power volume density is 306.5 w/cm3, and the energy conversion efficiency is 60.3%. The output of the device with the same structure is five times higher than that of the commercial P (VDF-TrFE) piezoelectric film. The power conversion device may not need to use any energy collection device is directly used to drive microelectronic devices, such as some light series LED small bulb, can also be used to induce electrochemical reaction, such as cathodic protection electrochemical electrochemical polymerization of EDOT driver and metal corrosion. These excellent properties make the static electricity
【学位授予单位】：东华大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ340.64

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