柔性高灵敏单壁碳纳米管气体传感器研究

在柔性聚对二甲苯C基底上制作了基于单壁碳纳米管的小型化、高灵敏、反应快速的气体传感器。使用介质电泳集成碳管束,并利用单链脱氧核糖核酸修饰增强器件灵敏度。当传感器暴露在甲醇蒸气中时,会出现明显可重复的反应,它可以检测含量低至4.3×10-6的甲醇,并且在相当宽的体积分数范围有清晰的分辨能力。对于4.3×10-6的含量,未修饰的传感器对应电阻变化率是4.8%;经过脱氧核糖核酸修饰,电阻变化率增加到了12.3%。此外,该传感器还显示了很快的响应速度和很好的测试复验性。研究表明:这种柔性气体传感器在未来环境监测应用中有很好的前景。     

微型碳纳米管NH3气体检测系统

基于制备得到的微型碳纳米管NH3传感器,研制了一种便携式气体浓度检测系统。此系统由恒流源驱动,通过微控制单元实现自动检测。为了便于安装、维修与调试,该系统所有电路均采用模块化设计,检测系统可以比较精确地测量25 kΩ以内电阻的变化,可以精确检测5×10－6～50×10－6范围内NH3气体浓度。     

碳纳米管掺杂WO_3气敏元件敏感特性的研究

研究以碳纳米管(CNT)为掺杂剂制备的CNT-WO3旁热式气敏元件。采用球磨、超声分散的方法对碳纳米管进行分散处理,溶胶—凝胶方法制备WO3微粉,用SEM观察了WO3气敏材料的显微结构,测试了元件对丙酮的气敏性能。结果表明:碳纳米管存在于平均粒径为30~50 nm的WO3晶粒间,从而增加了材料的气孔率。碳纳米管掺杂元件对丙酮的灵敏度远高于纯WO3元件,质量分数为0.4%的掺杂量对丙酮有最高灵敏度,具有能检测低体积分数丙酮气体、选择性好的优点,特别是掺杂碳纳米管明显提高了WO3元件的响应速度。     

Electrical analysis of single-walled carbon nanotube as gigahertz on-chip interconnects

The single-walled carbon nanotube (SWCNT) is a promising nanostructure in the design of future high-frequency system-on-chip, especially in network-on-chip, where the quality of communication between intellectual property (IP) modules is a major concern. Shrinking dimensions of circuits and systems have restricted the use of high-frequency signal characteristics for frequencies up to 1000 GHz. Four key electrical parameters, impedance, propagation constant, current density, and signal delay time, which are crucial in the design of a high-quality interconnect, are derived for different structural configurations of SWCNT. Each of these parameters exhibits strong dependence on the frequency range over which the interconnect is designed to operate, as well as on the configuration of SWCNT. The novelty of the proposed model for solving next-generation high-speed integrated circuit (IC) interconnect challenges is illustrated, compared with existing theoretical and experimental results in the literature.     

一种氨敏配合物的合成与气敏特性

在二甲基甲酰胺（DMF）中合成了Fe(Ⅲ）与一分子2，2－联吡啶－1，1′－二氧化物（bipyO2）的新化合物[Fe(bipyO2)Cl2]Cl.1/6bipyO2。用元素分析，摩尔电导，红外光谱和紫外光谱等方法测它的组成。用该配合物制作的传感器对氨气有极高的敏感性和选择性，可用于氨气泄漏报警和对环境中氨气的实时监测。     

Molecular dynamics simulation of non-covalent single-walled carbon nanotube functionalization with surfactant peptides

Non-covalent functionalized single-walled carbon nanotubes (SWCNTs) with improved solubility and biocompatibility can successfully transfer drugs, DNA, RNA, and proteins into the target cells. Theoretical studies such as molecular docking and molecular dynamics simulations in fully atomistic scale were used to investigate the hydrophobic and aromatic π–π-stacking interaction of designing four novel surfactant peptides for non-covalent functionalization of SWCNTs. The results indicated that the designed peptides have binding affinity towards SWCNT with constant interactions during MD simulation times, and it can even be improved by increasing the number of tryptophan residues. The aromatic content of the peptides plays a significant role in their adsorption in SWCNT wall. The data suggest that π–π stacking interaction between the aromatic rings of tryptophan and π electrons of SWCNTs is more important than hydrophobic effects for dispersing carbon nanotubes; nevertheless SWCNTs are strongly hydrophobic in front of smooth surfaces. The usage of aromatic content of peptides for forming SWCNT/peptide complex was proved successfully, providing new insight into peptide design strategies for future nano-biomedical applications.     

Electronic properties and gas adsorption behaviour of pristine,silicon-, and boron-doped (8, 0) single-walled carbon nanotube: A first principles study

Carbon nanotubes (CNTs) have received enormous attention due to their fascinating properties to be used in various applications including electronics, sensing, energy storage and conversion. The first principles calculations within density functional theory (DFT) have been carried out in order to investigate the structural, electronic and optical properties of un-doped and doped CNT nanostructures. O₂, CO₂, and CH₃OH have been chosen as gas molecules to study the adsorption properties based on zigzag (8,0) SWCNTs. The results demonstrate that the adsorption of O₂, CO_2, and CH₃OH gas molecules on pristine, Si-doped and B-doped SWCNTs are either physisorption or chemisorption. Moreover, the electronic properties indicating SWCNT shows significant improvement toward gas adsorption which provides the impact of selecting the best gas sensor materials towards detecting gas molecule. Therefore, these pristine, Si-, and B-doped SWCNTs can be considered to be very good potential candidates for sensing application.     

Development of an ozone gas sensor using single-walled carbon nanotubes

This study deals with the fabrication of an ozone gas sensor using single-walled carbon nanotubes (SWCNTs) as sensing material. The SWCNTs are dispersed by N,N-dimethylformamide (DMF). The CNT-DMF solution was dropped between interdigitated electrodes’ fingers to fabricate ozone gas sensor. For ozone environment, a commercial ozone generator was introduced. To improve sensor response, the deposited carbon nanotubes network was thermally treated at high temperature in a furnace. The sensor exhibits high sensitivity to ozone gas at concentration as low as 50 ppb, and fast response time, which is promising for future commercialization of carbon nanotubes based ozone gas sensor.     

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.     

Dielectric oil coated single-walled carbon nanotube electrodes for stable, large-strain actuation with dielectric elastomers

Dielectric elastomers have shown remarkably large actuation strain and energy density. A wide range of novel applications have been conceptualized, but commercial devices have not materialized due to the high rates of failure during high-strain actuation. We report that the use of single-walled carbon nanotube (SWNT) layers with thicknesses in the tens of nanometers as the compliant electrodes in combination with dielectric oil can prolong the actuation durability by at least one order of magnitude. Even though the ultrathin SWNT electrodes can undergo localized self-clearing in the event of electrical breakdown, effectively deactivating the fault and enabling self-healing of the device, extended duration actuation at strains larger than 100% in area cannot be achieved. This is due to corona discharge of the highly porous SWNT electrodes that have sharp tips that amplify the electric field. We show that by applying a dielectric oil coating on the SWNT electrodes, the corona discharging is quenched and continuous actuation at larger than 150% strain for longer than 1500 min can be achieved. The combination of self-clearable SWNT electrodes with dielectric oil coating should improve the manufacturing yield and operational reliability of dielectric elastomer artificial muscles and push them closer to commercialization.     

Surface acoustic wave gas sensors based on polyisobutylene and carbon nanotube composites

Surface acoustic wave (SAW) gas sensors based on polyisobutylene (PIB) and composites (PIB and carbon nanotubes) as sensitive layers were investigated for the detection of octane and toluene (volatile organic compounds) and other atmospheric pollutants (H₂, CO, NO₂ and NH₃) at room temperature. In order to study the effect of nanotubes in the response of SAW sensors, several composites based on PIB with different percentages of multiwalled carbon nanotubes (MWNTs) were tested and compared to the response obtained from PIB SAW sensors. Sensors exhibit high responses and selectivity to volatile organic compounds (VOCs) with fast response and recovery times as well as good repeatability and reproducibility. Experimental results show as small percentages of nanotubes improve the response to octane.     

纳米碳管在HyperChem中的自动生成及其力学性能探究

HyperChem是当今国际上知名的物理化学软件之一。本文作者使用Visual Basic 5．0计算机语言环境,结合HyperChem的Tcl、Hcl语言及DDE功能,开发了HyperChem中自动生成纳米碳管的软件模块。然后,采用HyperChem及其提供的MM 力场,分别对自动生成的纳米碳管及另外一种富勒烯／纳米管的拉伸力学性能进行了尝试性的分子动力学模拟。本文的纳米碳管生成模块及纳米碳管拉伸力学性能探究对HyperChem用户进一步深入研究纳米碳管的性能具有实际的参考价值。     

Gas sensing properties of platinum derivatives of single-walled carbon nanotubes: A DFT analysis

The limitations of intrinsic carbon nanotube (CNT) based devices to examine toxic gases motivate us to investigate novel sensors which can possibly overcome sensitivity problems. Pt–CNT assemblies (with Pt deposited externally as well as internally Pt-doped ones) interacting with NO₂ and NH₃ are studied and compared with unmodified CNTs. DFT calculations show that Pt can enhance adsorption and charge transfer processes to a very large degree. Incoming gas molecules cause changes in the electronic structure and charge distribution of the Pt-substituted CNTs that are both larger and more far-reaching than in their unmodified counterparts. Their relatively high stability is unaffected by the complexation with NO₂ and NH₃. CNTs with defective surface were also investigated. The sensing performance of Pt-doped CNT is found to be superior to defected CNTs.     

Cyclic voltammetry on electrode surfaces covered with porous layers: An analysis of electron transfer kinetics at single-walled carbon nanotube modified electrodes

Cyclic voltammetry is recorded of the oxidation of ferrocyanide on a glassy carbon electrode modified with multiple layers of single-walled carbon nanotubes. The current response is interpreted in terms of semi-infinite planar diffusion towards the macro-electrode surface and in terms of oxidation of the electroactive species trapped in pockets in between the nanotubes. A thin layer model is used to illustrate the effects of diffusion within a porous layer. It is found that a semi-infinite planar diffusion model alone is not appropriate for interpreting the kinetics of the electron transfer at this electrode surface. In particular, caution should be exercised in respect of comparing voltammetric peak-to-peak potential separations between naked electrodes and nanotube-modified electrodes for the inference of electrocatalysis via electron transfer via the nanotubes.     

Vapor sensing properties of thermoplastic polyurethane multifilament covered with carbon nanotube networks

The volatile organic compound (VOC) vapor sensing properties of a novel kind of thermoplastic polyurethane multifilament - carbon nanotubes (TPU-CNTs) composites is studied. And the sensing is based on changes in the electrical resistance of the composites due to vapor contact. The composites were readily obtained by adhering CNTs on the surface layer of TPU by means of simply immersing pure TPU multifilament into CNT dispersion. The uniformly formed nanotube networks on the outer layer of composite multifilament are favorable for providing efficient conductive pathways. The resulting TPU-CNTs composites show good reproducibility and fast response (within seconds) of electrical resistance change in cyclic exposure to diluted VOC and pure dry air. The vapor sensing behaviors of the composites are related to CNT content, vapor concentration, and polar solubility parameters of the target vapors. A relatively low vapor concentration of 0.5% is detectable, and a maximum relative resistance change of 900% is obtained for the composite with 0.8 wt.% CNT loading when sensing 7.0% chloroform. It is proposed that both the disconnection of CNT networks caused by swelling effects of the TPU matrix and the adsorption of VOC molecules on the CNTs are responsible for the vapor sensing behavior of TPU-CNTs composite, while the former effect plays the major role.     

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。     

半经验方法用于不同尺寸单壁纳米管的稳定性研究

利用PM3方法对不同直径(1．6-40．7A)、长度(1．2-20．9A)和类型(扶手椅型、锯齿型及手性型)的开口单壁纳米管的热力学稳定性进行了系统研究。结果表明:直径大于10 A的比较稳定;扶手椅型比其他类型的稳定;直径相同时,长度长的比短的稳定;原子数相同时,具有适当长径比的结构较为稳定;扶手椅型的电子结构主要取决于纳米管的长度,而锯齿型则取决于管的直径。所得结论与其它量化计算结果以及实验观测相符合。     

Influence of Zn ion implantation on structures and field emission properties of multi-walled carbon nanotube arrays

The structures and field emission properties of multi-walled carbon nanotube arrays implanted with Zn+ by MEVVA ion implanter have been investigated.The results revealed that Zn+implantation induced structural damage and that the top of carbon nanotubes with multi-layered graphite structure were transformed into carbon nanowires with amorphous structure.Meanwhile,C:Zn solid solution was synthesized after Zn+ implantation.The turn-on field and threshold field were 0.80 and 1.31 V/μm,respectively for original...     

Terahertz transistors based on aligned carbon nanotube arrays

The wireless communication technology has greatly pro-moted the industry's demand for higher operating frequen-cies and wider bandwidth devices.In recent years,...