碳纳米管聚苯胺薄膜SAWSO2传感器的实验研究

以128°Y-LiNbO3晶体上实现的双声路声表面波(SAW)器件为载体,在器件的测量声路上制作了对SO2气体具有敏感作用的碳纳米管聚苯胺薄膜,提出了一种基于碳纳米管聚苯胺薄膜的SAW SO2气体传感器.该传感器中的双声路结构消除了因外界测量条件改变引起的测量误差,提高了传感器的可靠性和准确性.利用原位法制备的碳纳米管聚苯胺增加了SO2气体的吸附面积,提高了传感器的灵敏度.实验结果表明,基于碳纳米管聚苯胺薄膜的SAW SO2气体传感器在测量范围内对各种浓度的SO2气体具有好的响应特性;当输入体积分数为1×10-6时,传感器的响应灵敏度约为8.3 kHz,比单一聚苯胺薄膜高1.8 kHz.此外,该传感器也具有更好的线性特性.     

CMOS工艺聚酰亚胺电容型湿度传感器的研究

以正胶光刻和干湿刻蚀方法,结合CMOS工艺制备了聚酰亚胺电容型湿度传感器.研究了硅基、钼-铝栅条状电极湿度传感器的结构及亚胺化温度对其性能的影响.结果表明:相对湿度(RH)为20%～80%发生准静态变化时,该传感器的湿度-电容曲线具有较好的线性度;外界相对湿度在12%和92%间发生阶跃变化时,响应时间约为40 s.     

基于La0.7Sr0.3FeO3的微结构乙醇气体传感器的研制

以La0.7Sr0.3FeO3为敏感材料,设计制成了一种新型的共平面结构气体传感器.基于有限元分析软件Ansys对该传感器结构进行了优化设计.实验测得该传感器对于500ppm浓度乙醇气体的灵敏度为8.0,功耗为261mW,是同种敏感材料烧结型传感器功耗的2/3,响应时间约为1.5s,恢复时间约为2.5s,是一种功耗低、灵敏度高、稳定性好的微结构乙醇气体传感器.     

基于La0.7Sr0.3FeO3的微结构乙醇气体传感器的研制

以La0.7Sr0.3FeO3为敏感材料,设计制成了一种新型的共平面结构气体传感器.基于有限元分析软件Ansys对该传感器结构进行了优化设计.实验测得该传感器对于500ppm浓度乙醇气体的灵敏度为8.0,功耗为261mW,是同种敏感材料烧结型传感器功耗的2/3,响应时间约为1.5s,恢复时间约为2.5s,是一种功耗低、灵敏度高、稳定性好的微结构乙醇气体传感器.     

三电极碳纳米管传感器的极间距优化

三电极碳纳米管传感器各电极之间的间距大小是影响检测精度的关键因素之一。在用传感器阵列检测多组分气体混合物时,各传感器的极间距很难确定。为三电极碳纳米管气体传感器提出一种基于粒子群算法(PSO)的极间距优化方法。该方法包括设计极间距、组建由不同极间距的多个传感器组成的传感器阵列、建立包括极间距及检测离子电流的数据库、建立混合气体定量分析模型及极间距优化等步骤。采用多组由不同极间距的三个碳纳米管传感器构成的传感器阵列对NO和SO2 混合气体进行测量,其中各传感器的极间距均采用上述方法优化。实验结果显示,上述极间距优化方法能够有效地选择电极之间的最佳间距,优化极间距后的传感器也获得了更高的检测灵敏度。     

基于WS_2纳米片的柔性湿度传感器制备与测试

提出了一种基于WS_2纳米片的聚酰亚胺柔性湿度传感器,传感器柔性薄膜和叉指电容电极分别采用加热亚胺化工艺和丝网印刷制备得到,其制备工艺简单,成本低廉。实验表明该柔性湿度传感器能够测量25%RH～85%RH的湿度,且在高湿度范围内(60%RH～85%RH),该柔性湿度传感器的灵敏度高达50.42 pF/%RH。传感器的响应和恢复时间分别为11和26 s,具有较好的稳定性和重复性。此外,该柔性传感器的呼吸性能测试结果表明,其能够用于监测时间间隔为2～10 s的呼吸状态,暗示该传感器可用于某些和呼吸频率有关的疾病诊断。     

CMOS兼容电容型湿度传感器的理论模型

对一种与CMOS工艺兼容的电容型湿度传感器进行了理论推导,物理建模和模拟仿真.该湿度传感器是采用梳状铝电极结构,聚酰亚胺作为感湿介质.通过分析感湿介质的介电常数吸附水分后的变化,考虑其电场分布,对电容型湿度传感器的理论模型进行了研究和模拟.利用Matlab软件对理论模型进行仿真,结果表明所建模型比通常采用的Laconte模型更符合实验结果.     

CMOS兼容电容型湿度传感器的理论模型

对一种与CMOS工艺兼容的电容型湿度传感器进行了理论推导，物理建模和模拟仿真．该湿度传感器是采用梳状铝电极结构，聚酰亚胺作为感湿介质．通过分析感湿介质的介电常数吸附水分后的变化，考虑其电场分布，对电容型湿度传感器的理论模型进行了研究和模拟．利用Matlab软件对理论模型进行仿真，结果表明所建模型比通常采用的Laconte模型更符合实验结果．     

一种电极型MEMS电场传感器封装结构

为了提高MEMS电场传感器敏感芯片封装的环境适应性,该文提出一种新型的电极型MEMS电场传感器封装结构。区别于将传感器敏感芯片及探头放置于被测环境中,该文通过在MEMS电场传感器封装管壳外部增加封装电极,仅将封装电极暴露在被测环境中,有效避免了传感器敏感芯片封装管壳受到多种恶劣环境的干扰。研制出基于新型封装结构的MEMS地面电场传感器及探空电场传感器,仿真及试验结果表明,该结构传感器能够实现对电场高精度准确测量,在高湿、低温等恶劣环境下输出稳定可靠。     

一种用于湿度监测的LC无线无源传感器的制备与测试

提出了一种采用丝网印刷和亚胺化工艺制备的LC无线无源技术的二硫化钼(MoS2)/聚酰亚胺(PI)湿度传感器。对比了不同超声时间下的二硫化钼/聚酰亚胺复合材料的湿度敏感性能,得出对湿度最灵敏的材料为超声4 h的二硫化钼/聚酰亚胺材料。测试结果表明,制备的器件在量程10%RH～95%RH内具有较好的频率响应,频率变化值为6.205 MHz;在高湿度范围内(60%RH～95%RH),传感器的灵敏度可达153.59 kHz/%RH。此外,该传感器的响应和恢复时间分别为7.2 s和10.4 s,迟滞性误差约为5%RH且具有较好的稳定性。该传感器可广泛应用于化学合成和矿井环境等领域的湿度监测。     

碳纳米管场致发射结构的研究

碳纳米管以其特有的电学性质而成为一种优良的冷阴极材料。在场致发射器件中，真空度是决定发射稳定性的一个重要因素。如果碳纳米管阴极附近的真空度太低，将产生打火、气体电离、离子回轰阴极等问题，将导致阴极发射电流的迅速衰减。本文通过对基于碳纳米管冷阴极的二极管和三极管的场发射特性的实验，分挤了残余气体压强与外加电压、发射体工作时间的关系以及碳纳米管阵列的I-E曲线，利用这些结果可以优化碳纳米管场致发射结构的设计。     

MQS1型一氧化碳气敏元件

氧空位与材料的气敏特性有着密切的关系，气敏材料的电导率由氧空位的形成和氧化过程共同决定，氧空位浓度越大，气敏效应越明显。根据氧化锡的这一气敏机理，以９９．９９％的锡为原料，掺入合适的添加剂，制成了ＭＱＳ１型一氧化碳气敏元件。它的灵敏度高、选择性好、响应恢复快、受温度和湿度的影响小。     

电容型湿度传感器模型计算与分析

以菲克第二扩散定律为基础,建立湿度传感器器件三明治结构模型,对聚酰亚胺电容型湿度传感器进行全面数值模拟,分析其电场分布、升降湿的动态过程及响应时间,并与实验结果进行对比分析.引入了自由体积理论对湿度传感器升、降湿过程的影响,使模拟过程更加符合实际情况,结果显示模拟结果和实验数据吻合良好,并根据对模拟结果分析,发现电极宽度是制约传感器性能的关键参数.该模型能够较准确预测制备的电容型湿度传感器性能,以此来指导高性能湿度传感器研究.     

分散定向碳纳米管阵列的制备及场发射性能

利用脉冲电化学沉积技术,以NiSO4·6H2O为电镀液在镀Cr硅基片上沉积低密度、直径在150nm左右的Ni催化剂颗粒,在此基础上,采用乙炔、氨气作为气源,采用等离子体增强化学气相沉积(PECVD)技术制备分散定向的碳纳米管阵列。研究了等离子体预处理技术对纳米管制备的影响以及该阵列的场发射性能,证明低密度的碳纳米管阵列阴极能有效地降低场屏蔽效应,进而提高场发射性能,其场发射的开启电场强度约为2.39V/μm。     

基于聚酰亚胺材料的FBG湿度传感特性研究

提出了一种基于光纤布拉格光栅(FBG)侧面镀膜感湿的新型全光纤湿度计,选取具有高湿敏特性和线膨胀系数(9.432×10-5%RH)的改性聚酰亚胺(PI)作为湿敏材料。通过在FBG侧面涂覆5种不同厚度的PI薄膜,检测厚度对传感器灵敏度和响应时间的影响,实验结果与理论计算符合很好,通过测试,PI薄膜厚为21μm时,传感器的湿度灵敏度为2.67×10-6/%RH,响应时间小于8s,有很好的实际应用前景。     

High performance electric field micro sensor with combined differential structure

This paper presents a high performance electric field micro sensor with combined differential structure. The sensor consists of two backward laid micro-machined chips, each packaged by polymer and metal. The novel combined differential structure effectively reduces various environmental affections, such as thermal drift, humidity drift and electrostatic charge accumulation. The sensor is tested in near-ground place as well as balloon-borne sounding. In different weather conditions, the measureinent results showed good agreement with those of the commercial electric field mill.     

Hybrid Zinc Oxide Nanorods/Carbon Nanotubes Composite for Nitrogen Dioxide Gas Sensing

This study reports on the synthesis and fabrication of hybrid nanocomposite based on single-walled carbon nanotubes–ZnO nanorods (SWCNT-ZnONR) as resistive gas sensors for NO₂ detection. The sensor was prepared using the standard simple and cost-effective hydrothermal process. The sensor was characterized by x-ray diffraction (XRD) and scanning electron microscopy. The findings revealed enhanced porous SWCNT-ZnONR nanocomposites due to the high porosity of the SWCNT. It was also found that the sensor exhibited average response and recovery times of about 70 s and 100 s, respectively. The XRD peak at 26° indicated that the SWCNT pattern was not disturbed, while sensitivity increased with temperature up to 150°C, at which the sensitivity was maximum. Similarly, the sensor sensitivity increased with NO₂ concentration at all levels examined. Moreover, the results indicate that the sensor shows significant promise for NO₂ gas sensing applications.     

Room-Temperature Hydrogen Sensor with High Sensitivity and Selectivity using Chemically Immobilized Monolayer Single-Walled Carbon Nanotubes

Although semiconducting single-walled carbon nanotubes (sc-SWNTs) exhibit excellent sensing properties for various gases, commercialization is hampered by several obstacles. Among these, the difficulty in reproducibly fabricating sc-SWNT films with uniform density and thickness is the main one. Here, a facile fabrication method for sc-SWNT-based hydrogen (H₂) sensors with excellent reproducibility, high sensitivity, and selectivity against CO, CO₂, and CH₄ is reported. Uniform-density and monolayer sc-SWNT films are fabricated using chemical immobilized through the click reaction between azide-functionalized polymer-wrapped sc-SWNTs and immobilized alkyne polymer on a substrate before decorating with Pd nanoparticles (0.5–3.0 nm). The optimized sc-SWNT sensor has a high room-temperature response of 285 with the response and recovery times of 10 and 3 s, respectively, under 1% H₂ gas in air. In particular, this sensor demonstrates highly selective H₂ detection at room temperature (25 °C), compared to other gases and humidity. Therefore, the chemical immobilization of the monolayer SWNT films with reproducible and uniform density has the potential for large-scale fabrication of robust room-temperature H₂ sensors.     

Thin-Film Bulk-Acoustic-Resonator Gas Sensor Functionalized With a Nanocomposite Langmuir–Blodgett Layer of Carbon Nanotubes

A thin-film bulk acoustic resonator (TFBAR) based on a vibrating membrane of AlN/Si₃N₄ has been fabricated onto a silicon substrate and functionally characterized as gas sensor at a resonating frequency of 1.045 GHz. This novel TFBAR-based gas sensor has been functionalized by a sensing nanocomposite layer, prepared by a Langmuir-Blodgett (LB) technique, of single-walled carbon nanotubes (SWCNTs) embedded in a host matrix of organic material of cadmium arachidate. High-performance gas detection at room temperature of a SWCNT-coated TFBAR sensor has been reported. The sensing device exhibits high sensitivity (e.g., acetone: 12 kHz/ppm; ethylacetate: 17.3 kHz/ppm), fast response (within 2-3 min), slow reversibility (within 1 h), and good repeatability (les 5% variation) of response toward tested organic vapors of acetone, ethylacetate, and toluene.     

A high-speed capacitive humidity sensor with on-chip thermal reset

This paper reports a high-speed capacitive humidity sensor integrated on a polysilicon heater. A response time of 1.0 s and a sensitivity of 30.0 fF/%RH have been obtained. High speed is achieved using multiple polyimide columns having diameters of a few microns and allowing moisture to diffuse into them circumferentially. Using structures that eliminate the air-gap capacitance between the columns, the simulated sensor output drifts by only 1% when the relative dielectric constant in the air region changes from 1 to 10. A polysilicon heater is used to measure relative humidity levels >80% RH. An accuracy of ±3% RH has been obtained using this method, with measurement errors of ±0.5°C and ±2% RH in temperature and relative humidity, respectively. The heater also reduces the recovery time after wetting, enables the sensor to recover from contamination and aging, and allows the sensing film to be reset on demand during self-test protocols