Experimental research of optical fiber hydrogen gas sensing system based on palladium-silver alloy

A novel optical fiber hydrogen sensing system based on palladium (Pd) and sliver (Ag) is proposed. By direct current (DC) magnetron process, Pd/Ag alloy ultra-thin films were deposited on the substrate to eliminate the hydrogen embrittlement of sensor based on pure Pd. Several samples with different thin film thicknesses were fabricated at different substrate temperatures and tested in the optical fiber hydrogen sensor setup. We do a series of experiments for obtaining optimum sputtering parameters, such as optimum sputtering temperature and thickness of Pd/Ag alloy film. The humidity effect and reliability experiment for the optical fiber hydrogen gas sensor are reported in detail. The testing results demonstrate the Pd/Ag alloy is a promising material for optical fiber hydrogen gas sensor.     

An optical fiber hydrogen sensor with Pd/Ag film

A20 nanometer palladium-silver （Pd/Ag） ultra-thin film was used for hydrogen gas sensing. The atomic ratio of Pd： Ag was 3：1, the thin film was evaporated on the optical glass, the Pd/Ag alloy could increase the life and provide the stability of the sensing film. The artificial neutral network was used for processing the data collected from the optical fiber bundle hydrogen sensor, which could enhance the measuring accuracy, at the same time, the intrinsic and extrinsic influences were eliminated mainly. Experimental results and numerical simulation show the training method available, a linear precision of 0. 1% for the optical hydrogen sensor is achieved.     

Optical fiber hydrogen sensor based on light reflection and a palladium-sliver thin film

Thin alloy films of palladium(Pd) and silver(Ag) are deposited onto glass substrates via the direct current(DC) magnetron technique.The hydrogen sensor probe consists of optical fiber bundle and Pd/Ag optical thin film.when the sensor is exposed to hydrogen,the refractive index of Pd/Ag optical thin layer will diminish and cause attenuation changes of the reflective light.It is observed that the thickness of Pd/Ag alloy layer can affect the hydrogen sensor signal.Under different substrate temperatures,several Pd/Ag samples are coated with different thicknesses of Pd/Ag alloy,and the results of a hydrogen sensor based on reflective light from the Pd/Ag alloy thin film are discussed.     

采用钯镍薄膜的声表面波氢气传感器研究

该文对采用钯镍薄膜作为敏感膜的声表面波氢气传感器开展研究,以实现快速的氢气检测。传感器采用双通道差分振荡器结构,其中在传感通道器件声表面波传播路径上以磁控溅射法沉积钯镍薄膜,通过钯镍薄膜对氢气的快速和可逆物理吸附引起声表面波传播速度的变化,进而以差分振荡器频率信号来表征待测氢气浓度。通过传感实验以确定获得快速响应的钯镍的优化厚度。结果表明,在钯镍厚为40nm时,传感器获得的响应幅度与响应速度分别达5kHz和5s。     

一种基于表面等离子体共振的多模光纤H2传感器

报道了一种基于表面等离子体共振(SPR)的多模光纤H2敏传感器,是通过化学腐蚀多模光纤使纤芯裸露再镀上Pd-Ag合金膜所构成,并给出了相应的理论分析和实验制作过程。理论分析表明,对于0～4%范围内的H2浓度,兼顾测量范围、灵敏度和响应时间,合金膜厚度选择在20nm附近为宜;实验研究结果显示,用20nm厚的Pd-Ag合金膜和15mm的光纤作用长度,在温度为26℃、相对湿度为60%的条件下,传感器能探测0～4%浓度范围内的H2,响应时间小于50s。     

Optical hydrogen sensor based on etched fiber Bragg grating sputtered with Pd/Ag composite film

A novel fiber optical fiber hydrogen sensor based on etched fiber Bragg grating coated with Pd/Ag composite film is proposed in this paper. Pd/Ag composite films were deposited on the side-face of etched fiber Bragg grating (FBG) as sensing elements by magnetron sputtering process. The atomic ratio of the two metals in Pd/Ag composite film is controlled at Pd:Ag = 76:24. Compared to standard FBG coated with same hydrogen sensitive film, etched FBG can significantly increase the sensor’s sensitivity. When hydrogen concentrations are 4% in volume percentage, the wavelength shifts of FBG-125 μm, FBG-38 μm and FBG-20.6 μm are 8, 23 and 40 pm respectively. The experimental results show the sensor’s hydrogen response is reversible, and the hydrogen sensor has great potential in hydrogen’s measurement.     

磁控反应溅射SnO2薄膜的气敏特性研究

为研究SnO2薄膜的气敏特性,采用直流磁控反应溅射法制备了SnO2薄膜。探讨和分析了SnO2薄膜气敏元件的敏感机理。对SnO2薄膜的电阻和灵敏度的测试以及对实验结果的分析表明:SnO2薄膜厚度在150~400nm为宜,一般膜厚在250nm时较为敏感。在SnO2薄膜中掺入Pd、Pt、Ag等微量杂质可大大提高SnO2薄膜气敏元件的灵敏度,且使灵敏度的峰值向低温方向移动,增强了对H2、CO和C2H5OH等可燃气体的选择性、响应时间由3min缩短到0.5s以下。     

薄膜型光纤温度传感器的膜系设计

纳米薄膜与光纤的结合为新型感测提供了各种潜在可能.为了分析温度敏感薄膜的膜系设计及其对光纤温度传感器传感特性的影响,根据光学薄膜理论和光纤传感器的温度感测原理,探讨了光纤温度传感器中敏感薄膜的膜系设计,并构建了薄膜型光纤传感器的温度传感特性模型.以测试系统的参数、性能以及其对干涉光谱的要求为基础,设计了对称性较好的法布...     

An a-SiGe:H phototransistor integrated with a Pd film on glasssubstrate for hydrogen monitoring

A novel a-SiGe:H optoelectronic hydrogen gas sensing device has been developed. The optoelectronic gas sensing device integrated a high optical gain a-SiGe:H optical sensor with a sputtered palladium (Pd) film on a glass substrate. Through the mechanism of the Pd film's transmitted optical power modulated with the H₂ concentration in atmosphere, the device can be operated at room temperature with a wider range (50 ppm to 133000 ppm) and faster response, in comparison to a conventional Pd catalytic type H₂ sensors, thus providing a good candidate for hydrogen monitoring     

Fe-C合金膜光纤腐蚀传感器的制作及性能研究

为了在光纤纤芯上制备更符合要求的Fe-C合金膜,取代了氢氟酸(HF)腐蚀包层的方法,选用刀笔去除光纤的涂覆层和包层;分别使用物理气相沉积离子溅射金及Fe-C合金、物理气相沉积真空蒸镀Fe-C合金、化学镀铜4种方法使纤芯表面金属化。经过对比分析,选择在金膜和铜膜上继续利用电镀方法沉积上不同厚度的Fe-C合金膜,进而进行腐蚀传感实验。最后利用新的实验数据记录方法,并通过实验中不同厚度的Fe-C合金膜表现出的传感特点,提出了一个腐蚀定量监测方案。结果表明,通过离子溅射金使纤芯金属化是一个相对较好的方法,这为Fe-C合金膜光纤腐蚀传感器的进一步发展开启了新思路。     

基于MEMS的力传感器薄膜应变计加工工艺

提出了在铝合金基体上磁控溅射80Ni20Cr薄膜电阻应变计的加工工艺,说明了其工艺的实现步骤。采用低弹性模量的铝合金制作力传感器的弹性体可以提高力/力矩传感器的灵敏度。提出了一种适合MEMS加工的全平面的力/力矩传感器弹性体结构。并介绍了薄膜电阻应变计构成的微型六维力传感器和薄膜厚度的测量手段。通过实验证实,此种薄膜工艺的应用提高了力传感器的测量精度。     

表面等离子体共振增强ZnO/Ag薄膜发光特性研究

为了提高氧化锌光致发光强度,以磁控溅射氧化锌/银复合薄膜为研究对象,系统地研究了氧化锌薄膜的光学性质。实验中首先在硅衬底上用射频磁控溅射的方法沉积氧化锌/银复合薄膜,作为对比,同时沉积了一层氧化锌薄膜。通过扫描电子显微镜和原子力显微镜对样品的形貌及成份进行表征,并且在室温下测试样品在300~800 nm波长范围内的光致发光光谱。实验结果表明:所制得样品为均匀分布的氧化锌纳米薄膜,纯氧化锌光致发光光谱结果显示有波长位于378 nm左右的紫光、470 nm左右的蓝色发光峰存在,加入银薄膜后,氧化锌可见光区和紫外光区的光致发光光谱强度均有所增强,而且紫外光峰位出现了红移。实验结果结合样品吸收谱对光致发光机理的分析作了进一步的分析。     

磁控溅射法制备WO_3薄膜及其氢敏特性研究

采用直流反应磁控溅射法,在未抛光的Al2O3基片上制备WO3薄膜,在干燥空气中经过热处理;利用SEM观察薄膜表面形貌;通过XRD测量,对薄膜的晶体结构进行分析;薄膜氢敏特性测试采用静态配气法。经过400℃热处理,当工作温度在270℃时,对体积分数为3×10-4%H2的灵敏度达到了77,稳定性较高、选择性好、响应时间在15s以内。WO3薄膜是一种较理想的氢敏材料,在氢敏传感器的设计中必定会得到足够的重视和广泛应用。     

准确检测液相中氢气浓度的倾斜光纤光栅传感器

为了实现液相中氢气体积分数的准确检测,该文利用钯、氧化硅超疏水溶胶和倾斜光纤光栅制备了氢气传感器。首先,在倾斜光纤光栅表面采用磁控溅射法涂覆了一层致密的钯膜,用于响应氢气体积分数变化信息;然后,采用镀膜提拉法在钯膜表面涂覆一层氧化硅超疏水膜,用于阻止水分子进入钯膜内部,导致钯膜从光纤表面脱落,进而增强了传感器在液相环境下运行的稳定性。实验研究了钯膜厚度对传感器氢敏响应特性的影响,并利用传感器对液相中的氢气体积分数进行了检测。研究结果表明,传感器能准确响应液相中氢气体积分数的变化信息,当钯膜厚度为120 nm时,灵敏度达到-15.29 pm/%,最大相对误差为8.67%。     

Common path heterodyne optical fiber sensors

The common path type of differential heterodyne fiber-optic sensing scheme has been developed. It uses a polarization maintaining fiber as either a sensor or an optical lead and a dual-frequency dual-polarization laser beam. The sensing schemes are applied to the measurements of temperature, strain, force, pressure, rotation rate (gyro), magnetic and electric fields, and thin film thickness. The sensing scheme and main performances for each measurand are described. High precision and high stability as well as good linearity for each measurand are demonstrated     

A Pd-PdO Film Potentiometnc pH Sensor

Palladium-palladium oxide film formed by the RF reactive sputtering technique was used for pH measurement. The potentiometric mode of operation was employed and an Ag/AgCl electrode was used as the reference electrode. The Pd-PdO film was formed on both alumina and polycrystalline silicon, and sputtering conditions to produce Pd-PdO film with good pH response characteristics were empirically defined. The Pd-PdO showed good pH response, ~54 mV/[pH] at 25 °C over the pH range of 3-9. The temperature dependency and dissolved oxygen effect on the film when used as a pH sensor were investigated and discussed.     

锰铜薄膜超高压力传感器研究

锰铜计是一种特种传感器,主要用于测量冲击波产生的超高压力。其量程上限可达50GPa,是现有传感器中最高的。为满足国防工程的特殊需要,须进一步提高传感器的量程上限及缩短传感器的响应时间。笔者通过传感器的结构设计、敏感材料和封装材料的研制以及采用新的传感器制备工艺,制作了一种新型的薄膜化的锰铜传感器,所得到的主要结论及创新性的结果可归纳如下:     

Seeing Hydrogen in Colors: Low‐Cost and Highly Sensitive Eye Readable Hydrogen Detectors

There is a great interest in the development of reliable and low‐cost hydrogen sensors for applications in the hydrogen economy, industrial processes, space application, detection of environmental pollution, and biomedical applications. Here, a new type of optical detector that indicates the presence of hydrogen in concentration range 5 ppm to 0.1 vol% H₂ merely by a reversible and tunable color change is reported. The device takes advantage of the reversible change in optical properties of a Pd‐capped Y thin film upon exposure to H₂, while the color is tuned using the interference of light reflected between the Y and Pd layers. In this way, an eye‐readable optical sensor that circumvents the need for electronics and external digital readouts is created. Using surface modifications, the performance of the H₂ detector in humid and oxygen rich environment is greatly improved. Therefore, the device has the potential to be used for chemical and also biochemical/biomedical H₂ sensing applications such as breathe hydrogen tests.     

两类典型光纤型SPR传感器的理论模型比较

针对基于SPR效应的两类典型光纤型传感器:传统型包层腐蚀的镀金属多模光纤传感器、新型镀金属单模光纤光栅传感器,指出其不同的SPR模型处理方法及传感特性。首先,根据传统型SPR光纤传感器的结构特点,利用平板SPR理论给出反射谱特性,同时指出并证明薄膜光学理论在平板SPR结构中与平板SPR理论的等价性。其次,针对新型SPR光纤光栅传感器结构特点,依据模式耦合思想,结合SPW模式特征,提出了光纤光栅SPR结构的理论处理方法,得到了镀金膜三包层LPFG结构的透射谱。最后,对基于SPR效应的两类典型光纤型传感器的传感特性进行了比较分析,结果表明,两类传感器对环境折射率均具有较高的分辨率,但新型光纤光栅SPR传感器的分辨率高出传统SPR光纤传感器3个数量级。     

The TCR of Ni24.9Cr72.5Si2.6 thin films deposited by DC and RF magnetronsputtering

The temperature coefficient of resistance (abbreviated as TCR) of thin film resistors on some sensor chips,such as thermal converters,should be less than several ppm/℃.However,the TCR of reported thin films is larger than 5 ppm/℃.In this paper,Ni_24.9Cr_72.5Si_2.6 films are deposited on silicon dioxide film by DC and RF magnetron sputtering.Then as-deposited films are annealed at 450℃ under different durations in N₂ atmosphere. The sheet resistance of thin films with various thickness and annealing time are measured by the four probe resistivity test system at temperature of 20,50,100,150,and 200℃ and then the TCR of thin films are calculated. Experimental results show that the film with the TCR of only-0.86 ppm/℃ can be achieved by RF magnetron sputtering and appropriate annealing conditions.