电弧等离子体制备纳米ZnO的气敏特性

用Ｈ２＋Ａｒ电弧等离子体法制成纳米ＺｎＯ，ＺｎＯ－Ｆｅ，研究了其气敏特征及机理，结果表明：与其它制备方法相比，该方法制成的纳米ＺｎＯ气敏元件在没有贵金属掺杂的情况具有较高的灵敏度，工作温度为２００℃￣２５０℃，为常规元件的一半，纳米ＺｎＯ－Ｆｅ－Ｐｄ对液化石油气（ＬＰＧ）的选择性比纳米ＺｎＯ好，具有快速响应（〈１５ｓ）的恢复特性，能稳定地连续工作７０ｈ以上，可制作低功耗ＬＰＧ气敏元件。     

醇-水溶液加热法制备纳米ZrO2粉体及相关过程的研究

分析了醇－水溶液加热法制备纳米ＺｒＯ２（３Ｙ）粉体的过程及加热温度、时间对反应过程及最后所得粉体的影响。研究结果表明,该法制备纳米ＺｒＯ２粉体过程发生了一系列化学反应,这些反应使Ｙ２Ｏ３前趋体在ＺｒＯ２前驱体中均匀分布,Ｙ２Ｏ２在粉体煅烧期间逐渐渗透到ＺｒＯ２颗粒中使之转变为四方相。     

醇-水溶液加热法制备纳米ZrO2粉体及相关过程的研究

分析了醇－水溶液加热法制备纳米ＺｒＯ_２（３Ｙ）粉体的过程及加热温度、时间对反应过程及最后所得粉体的影响．研究结果表明：该法制备纳米ＺｒＯ_２粉体过程中发生了一系列化学反应,这些反应使Ｙ_２Ｏ_３前趋体在ＺｒＯ_２前驱体中均匀分布,Ｙ_２Ｏ_２在粉体煅烧期间逐渐渗透到ＺｒＯ_２颗粒中使之转变为四方相．只有当加热的温度足够高使得溶液的介电常数＜２５时,沉淀才可能发生．加热时间必须足够长,使反应完全．过短的加热时间致使沉淀不够完全时,容易产生团聚．     

SnO2超细粉体应用于低温气敏材料

采用超临界流体干燥技术制备了纳米级ＳｎＯ２粉体。通过简单的掺杂，测试了其对ＣＯ、Ｈ２气敏效果，使其检测温度分别降至３０℃和１２０℃左右。同时，通过对元件成型温度的考察，使其烧结温度比传统ＳｎＯ２元件下降１００￣２００℃。从而肯定了超细ＳｎＯ２可以大大节省能耗，适用于低温气敏材料。     

CeO2掺杂ZnO厚膜的制备及气敏性能的研究

采用sol-gel法制备ZnO及CeO2掺杂量分别为6%、7%和8%(质量分数)的ZnO粉体。通过XRD、SEM对材料的表面形貌和结构进行表征。研究了掺杂量对粉体制备的影响。采用静态配气法对该粉体制成的气敏元件进行测试,结果表明,在工作温度仅为85℃的条件下,7%(质量分数)CeO2-ZnO气敏传感器对饱和丙酮蒸汽的灵敏度最高达9634,响应时间为3s,恢复时间为2s;在较低浓度2.0×10-4时灵敏度也可达30左右。并对丙酮气敏传感器的气敏机理进行了进一步探讨。     

Ni-LaFeO3的微波化学制备及气敏性能研究

利用微波化学法制备了Ni掺杂的LaFeO3粉体,并对其晶体结构和性能进行表征与分析,结果表明,Ni掺杂LaFeO3粉体为单一正交钙钛矿结构,没有杂相峰出现,且LaFe0.9Ni0.1O3颗粒呈椭球状,颗粒粒径约为178nm,颗粒分散性较好;LaFe0.9Ni0.1O3元件在工作温度为200℃时对5.0×10-4甲醛气体的灵敏度为9,且具有良好的选择性,响应和恢复时间分别是20和30s。     

花状SnO2的制备及其气敏特性的研究

以乙二醇(C2H6O2)为有机溶剂,采用溶剂热法制备了花状SnO2纳米材料,并将制备的SnO2制成旁热式气敏元件.通过XRD,SEM等测试手段对SnO2纳米材料进行了表征,并初步分析了气敏元件对丙酮的敏感机理.制备的SnO2材料是由粒径约为10 nm的颗粒有规则的堆叠而成的直径约为3～4μm的花瓣清晰的多孔分级花状结构.研究发现,气敏元件对丙酮气体有很好的响应灵敏度.在最佳工作温度(350℃)时,检测的丙酮体积分数最低为1×10-6.对100 ppm丙酮的响应及恢复时间分别为40和50 s.且气敏元件对丙酮气体的响应灵敏度远高于对苯、甲苯、甲醇、甲醛、氨等气体的响应灵敏度.     

pH值对ZrO2粉体的收得率、晶体结构和粒度的影响

本文采用正交试验方法,研究了用ＮＨ４ＨＣＯ３作为沉淀剂的溶胶共沉淀法制备了ＺｒＯ２－Ｙ２Ｏ３陶瓷粉末时,溶液ＰＨ值对粉体的收得率、晶体结构、粒度的影响。结果表明ＰＨ＝５～６时,粉体平均收得率最高,发过９５％,ＰＨ＝４～５时,ＺｒＯ２粉体为单斜相结构,ＰＨ＝５时为四方相结构,而ＰＨ＝５～６时,大多数为四方相;ＰＨ＝４～％时,粉体平均粒径最小。     

聚合物分解法制备微波介质陶瓷粉体的研究

对采用聚合物分解（Ｐｅｃｈｉｎｉ）法制备ＭｇＴｉＯ３粉体进行了研究，通过地聚合中间产物进行红外光谱分析，研究了聚合物分解法制备了ＭｇＴｉＯ３陶瓷粉体的聚合反应过程及产物，并与用传统固相反应法制备粉体工艺进行对比，从而证明用聚合物分解法可获得单一－ＭｇＴｉＯ３相材料，并可降低粉体的煅烧温度。     

高频等离子体超声喷雾热解法制备CuO/Al2O3粉体

以硝酸盐水溶液为原料、高频感耦等离子体为加热源、超声雾化热解的方法制备ＣｕＯ／Ａｌ２Ｏ３粉体。研究发现，溶液浓度及等离子参数体条件对粉初始态的特性有很大影响，浓度越低，粉体越细。纯Ａｌ２Ｏ３粉为粒径在１μｍ左右的空心球或壳状碎片，ＣｕＯ粉由无定型海绵体与平均粒度为２０ｎｍ的超细粒子组成。混合溶液制得的粉体形貌随着Ｃｕ／Ａｌ原子比的变化而变化，ＣｕＯ与Ａｌ２Ｏ３熔点温度相差较大是导致粉体生成微观过程     

多壁碳纳米管湿度传感器频率特性(英文)

为了研究测试频率对传感器性能的影响,改善多壁碳纳米管(multi-walled carbon nanotubes,MWCNTs)湿度传感器检测方法并提高传感器检测精度,对传感器频率特性进行了分析.在玻璃衬底上利用蒸镀和光刻技术制作了叉指电极,在电极表面涂敷了MWCNTs-SiO2敏感薄膜,最后通过烧结完成传感器制作.利用饱和盐溶液法产生相应湿度值,并使用RCL自动测试仪对传感器进行测试,测试频率选择在1 kHz到500 kHz之间.对传感器频率特性进行了实验与理论分析,结果表明,该传感器电容值对环境湿度敏感,并且其敏感特性受传感器检测频率的影响.使用毛细凝聚理论以及电解质物理理论对上述实验现象进行了合理的解释.传感器静态电容以及对湿度的灵敏度均随着测试频率的增加明显降低,测试频率为500 kHz时传感器灵敏度仅为测试频率1 kHz时的0.24倍.     

Fast, ultrasensitive virus detection using a Young interferometer sensor

We report the application of an integrated optical Young interferometer sensor for ultrasensitive, real-time, direct detection of viruses. We have validated the sensor by detecting herpes simplex virus type 1 (HSV-1), but the principle is generally applicable. Detection of HSV-1 virus particles was performed by applying the virus sample onto a sensor surface coated with a specific antibody against HSV-1. The performance of the sensor was tested by monitoring virus samples at clinically relevant concentrations. We show that the Young interferometer sensor can specifically and sensitively detect HSV-1 at very low concentrations (850 particles/mL). We have further demonstrated that the sensor can specifically detect HSV-1 suspended in serum. Extrapolation of the results indicates that the sensitivity of the sensor approaches the detection of a single virus particle binding, yielding a sensor of unprecedented sensitivity with wide applications for viral diagnostics.     

生物传感用巨磁电阻传感器及其磁珠检测性能

本文采用直流磁控溅射沉积了结构为NiFeCo(缓冲层)/[Cu/NiFeCo]×10/ Ta,巨磁电阻(GMR)值为9.8%的多层膜,利用微细加工技术制备了基于此GMR多层膜的生物传感器,GMR电阻线条的线宽分别为3μm和5μm.测试了单个GMR传感器的特性,并将该传感器件和外接可调电阻组成惠斯通电桥,采用该GMR电桥对Dynal公司的MyOne磁珠进行了检测.分别测试了施加变化垂直磁场和施加间歇式恒定垂直磁场时GMR电桥信号对传感器表面覆盖磁珠的响应,研究了GMR电桥信号和磁珠覆盖率的关系.选用器件电阻线宽分别为3μm和5μm的传感器测试了器件线宽对传感器灵敏度的影响.结果表明,GMR传感器能够检测到磁珠的存在,最低能检测的磁珠数量约100个,且GMR电桥信号与磁珠覆盖率基本成正比,器件的灵敏度与传感器线宽基本成反比.     

交流信号检测的多壁碳纳米管湿度传感器模型(英文)

为研究交流信号检测的多壁碳纳米管(MWCNTs)湿度传感器模型,通过扫描电子显微镜对传感器敏感薄膜(MWCNTs-SiO2薄膜)的孔隙结构进行观察,并使用表面积与孔隙(ASAP)分析系统对薄膜孔隙率进行分析.利用Debye方程对敏感薄膜中凝聚出液态水介电损耗的描述建立传感器模型.为了验证该传感器模型,制作了一种基于MWCNTs-SiO2的电导型湿度传感器,在100 kHz测试频率下,对不同相对湿度环境中的传感器电导值进行测试,利用测试结果与所建立模型进行拟合,发现R2大约为0.979,可见该模型可以用来描述传感器湿敏特性.     

Optical leaky waveguide sensor for detection of bacteria with ultrasound attractor force

An integrated, sensitive, and rapid system was developed for the detection of bacteria. The system combined an optical metal-clad leaky waveguide (MCLW) sensor with ultrasound standing waves (USW). The performance of a MCLW sensor for the detection of bacteria has been increased (>100 fold) by using USWs to drive bacteria onto the sensor surface. By forming the USW nodes at or within the surface of the MCLW, the diffusion-limited capture rate has been replaced by fast movement. Immobilized anti-BG antibody on the MCLW sensor surface was used to capture Bacillus subtilis var. niger (BG) bacterial spores driven to the surface. This combination of sensor and attractor force combination has been tested by detecting the evanescent scattering from bacterial spores at the sensor surface. Application of ultrasound for 3 min gave a detection limit for BG bacterial spores of 1 x 10(3) spores/mL.     

PDC-SiBCN陶瓷基无线无源温度传感器的性能EI北大核心CSCD

以耐高温聚合物先驱体陶瓷(PDC-SiBCN)为温敏介质材料,金属铂作为谐振腔材料,并在陶瓷表面开槽形成共面天线,制备出集开槽天线与谐振器一体的无线无源温度传感器,实现温度信息的无线无源传输。结果表明:传感器的谐振频率随测试温度的升高呈单调递减变化,PDC-SiBCN陶瓷的介电常数随温度的升高而单调增加,其中热解温度为1000℃的传感器测试温度达1100℃,具有优异的耐高温性和介温特性。同一测试温度下传感器的谐振频率随直径的增大而减小,也随热解温度的升高而降低。通过对传感器的谐振频率-温度拟合曲线进行一阶偏导得到灵敏度方程,传感器在1100℃的高温下有较高的灵敏度。传感器具有良好的循环稳定性能,在室温下实际无线传输距离达到42 mm,当测试温度为1100℃时传输距离可达8 mm,可应用于高温恶劣环境下航空发动机的温度监控。     

不同测试电压下多壁碳纳米管湿度传感器的稳定性(英文)

为提高碳纳米管(CNTs)湿度传感器的检测精度,研制了一种电阻型碳纳米管湿度传感器.阐述了传感器的结构、工作原理与制作过程,并对传感器的稳定性进行了实验与理论分析.建立并求解了对应于两根碳纳米管间势垒的薛定谔方程.分析结果表明传感器内部碳纳米管的稳定决定了传感器的稳定性,并且测试电压会影响碳纳米管的稳定性对传感器电阻波动的影响.实验结果表明传感器的工作电压影响着传感器的稳定性,当测试电压为5V时传感器电阻波动范围大约是工作电压为15 V时的5倍.     

Ammonia vapor sensing properties of polyaniline-titanium(IV)phosphate cation exchange nanocomposite

In this study, the electrically conducting polyaniline-titanium(IV)phosphate (PANI-TiP) cation exchange nanocomposite was synthesized by sol-gel method. The cation exchange nanocomposite based sensor for detection of ammonia vapors was developed at room temperature. It was revealed that the sensor showed good reversible response towards ammonia vapors ranging from 3 to 6%. It was found that the sensor with p-toluene sulphonic acid (p-TSA) doped exhibited higher sensing response than hydrochloric acid doped. This sensor has detection limit ≤1% ammonia. The response of resistivity changes of the cation exchange nanocomposite on exposure to different concentrations of ammonia vapors shows its utility as a sensing material. These studies suggest that the cation exchange nanocomposite could be a good material for ammonia sensor at room temperature.     

The RF-powered surface wave sensor oscillator--a successful alternative to passive wireless sensing

A novel, passive wireless surface acoustic wave (SAW) sensor providing a highly coherent measurand proportional frequency, frequency modulated (FM) with identification (ID) data and immune to interference with multiple-path signals is described. The sensor is appropriate for bandwidth-limited applications requiring high-frequency accuracy. It comprises a low-power oscillator, stabilized with the sensing SAW resonator and powered by the rectified radio frequency (RF) power of the interrogating signal received by an antenna on the sensor part. A few hundred microwatts of direct current (DC) power are enough to power the sensor oscillator and ID modulation circuit and achieve stable operation at 1.0 and 2.49 GHz. Reliable sensor interrogation was achieved over a distance of 0.45 m from a SAW-based interrogation unit providing 50 mW of continuous RF power at 915 MHz. The -30 to -35 dBm of returned sensor power was enough to receive the sensor signal over a long distance and through several walls with a simple superheterodyne FM receiver converting the sensor signal to a low measurand proportional intermediate frequency and retrieving the ID data through FM detection. Different sensor implementations, including continuous and pulsed power versions and the possibility of transmitting data from several measurands with a single sensor, are discussed.     

A glucose sensor made of an enzymatic clay-modified electrode and methyl viologen mediator

A novel glucose sensor has been contrived by immobilizing glucose oxidase between two nontronite clay coatings on glassy carbon electrode with methyl viologen as mediator. The sandwich configuration proved to be very effective in the determination of glucose. The response of the glucose sensor was determined by measuring cyclic voltammetric peak current values under aerobic solution conditions. The effects of the amount of enzyme immobilized, the operating pH, and the common interferences on the response of the glucose sensor were studied. The detection limit was 5 μM, with a linear range extending to about 6 mM, giving a dynamic range of over 3 orders of magnitude for 0.1 mM methyl viologen. When stored in pH 7 phosphate buffer at 4 °C, the sensor shows almost no change in performance after operating for at least 2 months. A mechanism for the operation of the glucose sensor is also proposed.