基于聚苯胺及其复合材料的QCM气体传感器研究

发布时间：2018-03-29 07:37

本文选题：气体传感器　切入点：石英晶振微天平　出处：《大连交通大学》2015年硕士论文

【摘要】：石英晶振微天平(Quartz Crystal Microbalance,QCM)气体传感器是以石英晶体表面敏感薄膜为敏感元件,以AT切型石英晶体为换能元件,利用石英晶体的质量-频率变化关系,将待测气体的浓度信号转换成频率信号输出,从而实现气体浓度的检测。本文以研制监测水果在仓储、运输等过程中新鲜程度的传感器为目的,对石英晶振微天平气体传感器及其应用进行了深入研究,研制出分别对香蕉和苹果气具有良好敏感特性的QCM水果气体传感器。以基频6MHz的石英晶体为基片,运用一步原位聚合法在其上沉积了对甲苯磺酸(TSA)掺杂聚苯胺以及SnO2掺杂度分别为10%、20%、50%的PANI/SnO2复合气敏薄膜,制作出QCM水果气体传感器样品;设计了相应的起振、整形、差频、频压转换及数据采集电路,并搭建了气敏性能测试平台。在室温下,分别测试了上述传感器对放置不同天数的苹果、香蕉释放气体的敏感特性并对实验结果进行了比较与分析,从中筛选出来响应速度快、灵敏度高、重复性好的传感器。研究结果表明:对纯PANI敏感薄膜来说,在一定范围内,TSA掺杂浓度增加会改善传感器的气敏性能。传感器对放置不同天数的苹果释放气体频率变化量有较大差异,由新鲜到腐烂传感器的频率变化量增大。SnO2掺杂度为10%的传感器敏感特性最好,对三个阶段的苹果气的响应分别为:581.49Hz、730.95Hz和1098.701Hz。当传感器的频率变化量大于1058Hz时,可以初步判断苹果已经腐烂,此时传感器的频率变化量趋于稳定。而对香蕉释放气由新鲜到成熟的过程中传感器的频率变化量急剧增加,当香蕉开始腐烂时,传感器的频率变化量开始减小,最后趋于稳定。PANI传感器对香蕉气体表现出最好的敏感特性,三个阶段的响应分别为:1070.53Hz、2451.12Hz和1834.68Hz。此传感器可用来判断香蕉是否成熟,当传感器的频率变化量大于2309Hz时,可以初步判断香蕉进入成熟期。用质谱仪对三种不同程度的苹果和香蕉释放气进行了分析,发现水果释放气为多种成分气体的混合,不同成熟度时各组分气体的浓度明显不同,因此传感器表现出对放置不同天数的苹果和香蕉释放气具有不同的响应特性。实验结果表明,本文研制的QCM水果释放气传感器具有灵敏度高、线性度好、响应速度快、重复性好等优点,有望在水果仓储运输方面得以应用。
[Abstract]:Quartz crystal microbalance Quartz Crystal microbalance (QCM) gas sensor is based on quartz crystal surface sensitive film as sensitive element, AT cut quartz crystal as energy transfer element, using quartz crystal mass-frequency change relationship. The concentration signal of the gas to be measured is converted into a frequency signal output to realize the detection of the gas concentration. The purpose of this paper is to develop a sensor to monitor the freshness of fruits during storage and transportation. The quartz crystal microbalance gas sensor and its application are studied in this paper. A QCM fruit gas sensor with good sensitivity to banana and apple gas is developed. The quartz crystal of 6MHz is used as substrate. The samples of QCM fruit gas sensor were prepared by one-step in situ polymerization on which the polyaniline doped with p-toluenesulfonic acid and the PANI/SnO2 composite gas sensing film with SnO2 doping degree of 10 ~ 20% and 50% respectively were prepared, and the corresponding starting vibration, shaping and differential frequency were designed. The frequency voltage conversion and data acquisition circuit were used to test the gas sensing performance. At room temperature, the sensitivity of the sensors to the gas released from apples and bananas for different days was tested, and the experimental results were compared and analyzed. The sensors with high response speed, high sensitivity and good reproducibility were screened out. The results show that: for pure PANI sensitive films, The increase of TSA doping concentration in a certain range will improve the gas sensing performance of the sensor. The sensor with 10% SnO2 doping degree has the best sensitivity when the frequency change of the sensor is increased from fresh to decaying. The response to apple gas in the three stages is: 1: 581.49 Hz, 730.95Hz and 1098.701Hz, respectively. When the frequency change of the sensor is larger than that of 1058Hz, It can be preliminarily judged that the apple has rotted, and the frequency change of the sensor tends to be stable. However, the frequency change of the sensor increases sharply during the process of releasing gas from fresh to mature. When the banana begins to rot, The frequency change of the sensor began to decrease, and finally tended to stabilize. Pani sensor showed the best sensitivity to banana gas. The response of the three stages was 1070.53Hzn 2451.12Hz and 1834.68Hz. the sensor could be used to judge whether the banana was mature or not. When the frequency change of the sensor is greater than that of 2309Hz, it can be preliminarily judged that banana has entered into mature stage. Three kinds of gas released from apple and banana are analyzed by mass spectrometer, and it is found that the gas released from fruit is a mixture of many components. The gas concentration of each component is obviously different at different maturity, so the sensor has different response characteristics to apple and banana release gas placed in different days. The experimental results show that, The QCM fruit release gas sensor developed in this paper has the advantages of high sensitivity, good linearity, fast response speed and good repeatability. It is expected to be applied in fruit storage and transportation.
【学位授予单位】：大连交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ317;TB33;TP212

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