Gas sensing properties at room temperature of a quartz crystal microbalance coated with ZnO nanorods

Gas sensors based on a quartz crystal microbalance (QCM) coated with ZnO nanorods were developed for detection of NH₃ at room temperature. Vertically well-aligned ZnO nanorods were synthesized by a novel wet chemical route at a low temperature of 90 °C, which was used to grow the ZnO nanorods directly on the QCM for the gas sensor application. The morphology of the ZnO nanorods was examined by field-emission scanning electron microscopy (FE-SEM). The diameter and length of the nanorods were 100 nm and 3 μm, respectively. The QCM coated with the ZnO nanorods gas sensor showed excellent performance to NH₃ gas. The frequency shift (Δf) to 50 ppm NH₃ at room temperature was about 9.1 Hz. It was found that the response and recovery times were varied with the ammonia concentration. The fabricated gas sensors showed good reproducibility and high stability. Moreover, the sensor showed a high selectivity to ammoniac gas over liquefied petroleum gas (LPG), nitrous oxide (N₂O), carbon monoxide (CO), nitrogen dioxide (NO₂), and carbon dioxide (CO₂).     

采用聚吡咯修饰的QCM型三甲胺气体传感器

三甲胺是评估肉类食品新鲜度的重要指标之一,并且临床上也比较值得关注,因而三甲胺的检测具有十分重要的意义,为此,我们采用乳聚法制备了聚吡咯材料,并将其涂敷在晶振电极表面后制得敏感石英晶体微天平(QCM).根据敏感QCM和参比QCM间的频率差变化来实现气体的检测.在室温条件下,该气体传感器对三甲胺气体具有较明显的响应.实验从灵敏度、重现性、选择性和稳定性等方面出发,对该传感器的的性能进行了评价.结果表明,虽然传感器的制备方法简单,但它的性能优异.     

Development and evaluation of piezoelectric-polymer thin film sensors for low concentration detection of volatile organic compounds related to food safety applications

In this study, the regioregular poly (3-hexyl thiophene) (rr-P3HT) based piezoelectric sensors were developed and evaluated to detect alcoholic volatile organic compounds (VOCs) associated with spoiled and Salmonella typhimurium contaminated packaged beef headspace. The drop coating technique was used to deposit thin films of rr-P3HT on both the sides of quartz crystal microbalance (QCM) electrode. The QCM polymer sensors were found to provide repeatable and reproducible sensor response to alcohol VOCs with a fast recovery (<2 min) at room temperature (25 °C). The principal component analysis on the sensors sensitivities was performed to discriminate the sensed alcohol VOCs, namely: 3-methyl-1-butanol from 1-hexanol. The QCM polymer sensors demonstrated selective response to low concentration of 3-methyl-1-butanol (average estimated lowest detection limit (LDL): 4.35 ppm) and to 1-hexanol (average estimated LDL: 3.20 ppm). The 30 days storage study performed on QCM sensors showed identical sensitivity responses for sensing 3-methyl-1-butanol and 1-hexanol at low concentrations.     

Comparison of surface plasmon resonance spectroscopy and quartz crystal microbalance for human IgE quantification

Surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) have been known independently as surface sensitive analytical devices capable of label-free and in situ bioassays. In this study a SPR device and a 10 MHz QCM sensor are employed for the study of human IgE and anti-human IgE-binding reactions upon immobilizing the latter on the gold electrodes. The SPR and QCM response curves to the antibody immobilization and antigen binding are similar in shape but different in time scale, reflecting different resonation principles. Through optimization of the anti-human IgE coating, both the SPR and QCM sensors could detect IgE in a linear range from 5 to 300 IU/ml. Although the intrinsic sensitivity of the SPR device is five times of the 10 MHz QCM, the IgE detection sensitivity of the two methods is, however, different only in a factor of 2. The acceptable QCM sensitivity for the IgE detection is attributed to the fact that QCM measures the sum of molar mass of a protein layer and the entrapped water. Although both the devices use open, stand still liquid cell, and all the measurements are performed at room temperature, the SPR reproducibility and reliability are better than QCM, as the QCM frequency is more sensitive to temperature fluctuations, press changes and mechanical disturbances.     

热蒸发石墨烯基SnOx-Sn传感器气敏性研究

通过化学气相沉积法制备石墨烯并采用热蒸发法在石墨烯上沉积锡(Sn)及其氧化物,得到石墨烯基SnOx-Sn气敏传感器,研究其在室温下对低体积分数甲醛和二氧化氮(NO2)气体的气敏性及SnOx-Sn膜厚和基底加热温度对传感器气敏性的影响.通过场发射扫描电镜(FESEM)、原子力显微镜(AFM)等表征手段研究了石墨烯基SnOx-Sn气敏传感器的形态结构.     

基于PVDF膜的QCM对DMMP的气敏特性研究

神经性毒剂是化学战剂的重要分支.为了检测神经性毒剂模拟剂甲基膦酸二甲酯(DMMP),使用毛细管在压电石英晶体(QCM)的电极上滴涂上不同质量的聚偏氟乙烯(PVDF)溶液,干燥后作为敏感膜.室温下测试QCM对不同浓度的DMMP的响应情况,发现QCM的频率变化与气体浓度有着良好的线性关系.该实验结果表明,PVDF可以作为检测DMMP的很好的敏感材料.     

ZnO纳米棒修饰的QCM气体传感器检测NH_3研究

主要介绍了ZnO纳米棒修饰的石英晶体微天平(QCM)气体传感器的制备与测试。采用两步法在石英晶振片表面制备直径为100 nm的ZnO纳米棒敏感膜,构成QCM NH3传感器。检测系统为自主研发的基于LabVIEW平台的QCM气体传感器频率测试软件。检测NH3的体积分数为5×10-6~50×10-6,响应时间均在10 s以内,最大频差值为10.9 Hz,响应最大频差值与NH3体积分数呈现良好的线性关系。室温条件下,ZnO纳米棒敏感膜可以完全实现吸附解吸过程,具有可逆性。该传感器性能稳定,响应灵敏,具有重复性。     

Flexible H2 sensor fabricated by layer-by-layer self-assembly of thin films of polypyrrole and modified in situ with Pt nanoparticles

A novel flexible H₂ gas sensor was fabricated by the layer-by-layer (LBL) self-assembly of a polypyrrole (PPy) thin film on a polyester (PET) substrate. A Pt-based complex was self-assembled in situ on the as-prepared PPy thin film, which was reduced to form a Pt-PPy thin film. Microstructural observations revealed that Pt nanoparticles formed on the surface of the PPy film. The sensitivity of the PPy thin film was improved by the Pt nanoparticles, providing catalytically active sites for H₂ gas molecules. The interfering gas NH₃ affected the limit of detection (LOD) of a targeted H₂ gas in a real-world binary gas mixture. A plausible H₂ gas sensing mechanism involves catalytic effects of Pt particles and the formation of charge carriers in the PPy thin film. The flexible H₂ gas sensor exhibited a strong sensitivity that was greater than that of sensors that were made of Pd-MWCNTs at room temperature.     

Formaldehyde sensors based on nanofibrous polyethyleneimine/bacterial cellulose membranes coated quartz crystal microbalance

A novel formaldehyde sensor based on nanofibrous polyethyleneimine (PEI)/bacterial cellulose (BC) membranes coated quartz crystal microbalance (QCM) has been successfully fabricated. The nanoporous three-dimensional PEI/BC membranes are composed of nanofibers with diameter of 30-60 nm. The sensor showed high sensitivity with good linearity and exhibited a good reversibility and repeatability towards formaldehyde in the concentration range of 1-100 ppm at room temperature. Moreover, the results showed that the sensing properties were mainly affected by the content of PEI component in nanofibrous membranes, concentration of formaldehyde and relative humidity. Additionally, the nanofibrous PEI/BC membrane coated QCM sensors exhibited a good selectivity to formaldehyde when tested with competing vapors. The simple and feasible method to prepare and coat the PEI/BC sensing membranes on QCM makes it promising for mass production at a low cost.     

SnO2基薄膜气体传感器制作与敏感性测试

在现有的粉末烧结型SnO2基气敏传感器基础上研制了薄膜型SnO2基气体传感器,以抛光的丽热石英玻璃为基片,真空磁控溅射50～70nm厚度的SnO2薄膜,在SnO2薄膜上分别溅射不连续的ZnO、Al2O3、CeO2、InO2等薄膜,传感器背面溅射30μm的Ni80Cr20电阳合金作为传感器加热电阻,用薄膜热电偶测量传感器工作温度。测试了不同的复合瞑对传感器灵敏度和选择性的影响,并对传感器的吸附与解吸速度进行了测试,薄嗅传感器达到相同灵敏度所需的工作温度比粉末烧结型传感器下降100～150℃,吸附解吸速度比粉末烧结型快。     

PPy-CeO2复合薄膜柔性NO2传感器的制备与气敏特性研究

以吡咯(Py)单体为前驱液,六水合三氯化铁(FeCl3·6H2O)为氧化剂,通过化学氧化聚合法与自组装相结合工艺在柔性聚酰亚胺(PI)衬底上制备聚吡咯-二氧化铈(PPy-CeO2)复合薄膜.通过紫外-可见吸收光谱(UV-Vis)、傅立叶红外光谱(FTIR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)及X射线衍射(XRD)、X射线电子能谱分析(XPS)对纯PPy和PPy-CeO2复合材料进行了表征分析,结果表明PPy-CeO2呈典型的核-壳结构.在室温条件下研究了纯PPy薄膜和PPy-CeO2复合薄膜对二氧化氮(NO2)的响应特性,结果表明,PPy-CeO2复合薄膜传感器显示出更优的响应特性,灵敏度为纯PPy薄膜传感器的12.6倍,且具有良好的重复性和选择性.最后讨论分析了PPy-CeO2复合薄膜传感器的NO2敏感机理.     

聚苯胺-多壁碳纳米管薄膜SAW NO2传感器

将聚苯胺-多壁碳纳米管聚合物沉积于声表面波(SAW)气体传感器的敏感区,形成敏感薄膜,实现了室温下对不同体积分数NO2的检测.研究表明:这种传感器具有很高的敏感性,良好的重复性和低体积分数检测极限.同时,单一聚苯胺薄膜也做了对比测量,实验结果表明:聚苯胺-多壁碳纳米管聚合物敏感膜比单一聚苯胺薄膜具有更高的敏感性和更短的...     

表面碳化的硅纳米孔柱阵列的H2S室温电容传感特性

通过将硅纳米孔柱阵列(Si-NPA)进行高温碳化处理,制备出一种SiC/Si-NPA复合纳米体系。对SiC/Si-NPA的表面形貌和结构表征揭示,生长于Si-NPA上的SiC薄膜由具有立方结构的SiC纳米颗粒组成,厚度为～200 nm。SiC/Si-NPA整体上保持了Si-NPA原有的柱状阵列结构特征。对浓度介于0～1 200×10-6的H2S气体的室温传感性能测试表明,SiC/Si-NPA对H2S气体的电容响应灵敏度可高达790%,而其对400×10-6浓度H2S气体的响应和恢复时间则分别为170 s和200 s,元件具有较好的测量重复性和稳定性。SiC/Si-NPA可能是一种室温条件下较为理想的H2S气体传感材料。     

Characterization of layer-by-layer nano self-assembled carbon nanotube/polymer film sensor for ethanol gas sensing properties

This paper reported a multi-wall carbon nanotubes (MWNTs)/polymer film-based sensor for ethanol gas detection. The film sensor was fabricated using layer-by-layer self-assembly method on the substrate with interdigital electrodes structure. The surface morphology of the self-assembled membranes shows a high strength, dense and random network structures, and the electrical properties of MWNTs/polymer film sensor were investigated. Its ethanol gas-sensing properties with varying gas concentration are characterized at room temperature. The experiment results shown that carboxylic groups attached on the MWNTs surface and the expansion of polyelectrolyte interlayer lead to a prompt response and sensitive resistance change when the sensor exposed to ethanol gas, indicating the unique advantages of layer-by-layer self-assembly of MWNTs/polymer film sensors in prospective application.     

涂敷脲醛树脂的石英晶体微天平湿度传感器

在碱性条件下预先合成脲醛树脂单体,然后在酸性条件下于石英晶体的电极上原位合成脲醛树脂高分子薄膜,制备了石英晶体微天平湿度传感器。同时考察敏感膜厚度对检测灵敏度的影响以及传感器的响应特性、重复性和稳定性。试验结果表明:涂敷脲醛树脂薄膜的传感器频率随测试的相对湿度变化明显,传感器具有良好的重复性和稳定性。制作的湿度传感器可应用于实际的生产、生活中。     

四苯基卟啉薄膜/K+-交换玻璃光波导传感器的研制及其气敏性研究

利用Alder法合成了四苯基卟啉并进行了表征;用匀胶机将一定浓度的四苯基卟啉溶液做成薄膜固定在钾离子（K+）交换玻璃光波导表面,研制了高灵敏的四苯基卟啉薄膜/K+-交换玻璃光波导传感器,并对挥发性有机气体进行检测。实验结果表明,在室温下该传感器对低浓度的苯乙烯、二甲苯、甲苯等蒸气具有一定的响应,其中对二甲苯的响应最大,能检测到1×10-6（V/V0）的二甲苯蒸气。     

QCM 气体传感器的优化设计及应用研究

本文主要介绍了一种新型的石英谐振气体传感器 QCM(Quartz Crystal Microbalance) .它具有灵敏度高、稳定性好、抗干扰能力强等特点 ,可用于多种领域 ,本文主要根据计算化学方法 ,研究其对呼吸气体的响应特性 .此外 ,采用电化学方法制备传感器敏感膜 ,设计了相应的测量系统 .从实验结果可看出这一传感器对呼吸气体的响应结果是令人满意的 ,具有实际应用前景     

Measurement system for quartz crystal microbalance sensors

Human olfactory is studied for a long time and in many ways, and many of them are based on gas chromatography technology. They have used gas sensors made of metal-oxide semiconductors. The semiconductor sensors can detect gases as difference in electric resistance by oxidation or reduction of surface on the sensor. Human olfactory is organized by about 2,000 receptors of smell, and many electric sensors are used to emulate the receptors. We consider applying multi-channel QCM for these sensors. However, QCM sensors in a chamber (small box) interfere with each other, and we should examine measures of a design method for anti-interference. In this paper, we propose a design method and build an evaluation system.     

聚苯胺/TiO2修饰的QCM气敏传感器及湿度影响研究

用气敏传感器检测三甲胺在食品检验和环境监测等领域具有广泛意义,而湿度影响在这些实际应用中通常无法避免,如何补偿和校正湿度干扰是传感器设计和使用中的重要课题.考察了一种以聚苯胺/TiO2复合材料为敏感膜的QCM气敏传感器在干燥和不同湿度气氛中对三甲胺气体的响应特性,结果表明均呈现出良好的线性敏感性.发现了在湿度干扰下的传...     

Thin film polypyrrole/SWCNTs nanocomposites-based NH3 sensor operated at room temperature

A PPY/SWCNTs nanocomposite-based sensor with relatively high sensitivity and fast response–recovery was developed for detection of NH₃ gas at room temperature. The gas-sensitive composite thin film was prepared using chemical polymerization and spin-coating techniques, and characterized by Fourier transformed infrared spectra and field-emission scanning electron microscopy. The results reveal that the conjugated structure of the PPY layer was formed and the functionalized SWCNTs were well-embedded. The effects of film thickness, annealing temperature, and SWCNTs content on gas-sensing properties of the composite thin film were investigated to optimize the gas-sensing performance. The as-prepared thin film PPY/SWCNTs composite sensor with optimized process parameters had a response of 26–276% upon exposure to NH₃ gas concentration from 10 to 800 ppm, and their response and recovery times were around 22 and 38 s, respectively.