硅基热电堆真空传感器的耦合场分析

利用商业化的1．2μm标准CMOS生产流水线,配合无掩模体硅各向异性腐蚀工艺,制造了一种热电堆型真空传感器,器件敏感部分尺寸为124um×100μm,由5层薄膜组成,最大厚度为3．2μm．采用一种简化方式对传感器建立有限元模型．新模型一方面忽略了气体对流和热辐射的传热作用,另一方面将各层介质和热电堆结构层分别进行了合并．模型具有简单的断面结构,网格划分容易,收敛速度快．运用ANSYS软件对模型进行了电一热、热一电耦合场分析,直接得到了1．5v加热电压驱动时不同压强下的热电堆输出电压,并与0．1～200Pa之间的测试结果进行比较,结果表明,采用简化建模方式的计算结果与测试结果之间的偏差小于6％．     

基于MEMS热电堆传感器的高温测量技术

为了拓宽MEMS热电堆传感器的温度测量范围,实现高温测量,根据MEMS热电堆传感器的原理,设计完成了A2TPM1334型MEMS热电堆传感器静、动态标定装置.通过试验得到标定结果;同时提供了基于MEMS热电堆传感器实现瞬态高温测试的技术方案及实现手段,并对其关键部分一红外衰减片性能进行了分析和讨论.     

压阻变换压力传感器的性能预测模型

热、压环境下压阻变换压力传感器的性能可以通过有限元方法预测．这里研究了简化的1／8模型,模型考虑了二氧化硅和氮化硅生成过程及堆阳极键合和胶粘结合过程．结果发现有限元预测结果和实验数据具有可比性．范例研究表明,硼硅堆导致产生一定的非线性,但它隔离了硬环氧树脂的非线性．在包装过程中最好使用柔性环氧黏合或软黏胶性结合．黏合材料的黏弹性和黏塑性将会导致传感器输出的滞后和漂移误差．然而,在相对稳定的环境下。软黏合剂对传感器的影响可以忽略．此外,详细的设计和过程信息有助于提高模型的适用性．     

MEMS热电堆高温测试系统中的MEMS传感器动态性能测试

传感器作为整个系统的核心部件,其性能对整个系统的指标起至关重要的作用,尤其是动态特性的优劣直接决定能不能测试到瞬态温度的变化。本文针对MEMS热电堆高温测试系统选定的A2TPMI型热电堆传感器进行静、动态性能标定,目的是为整个高温测试系统提供比较精确的传感器参数,为整个高温测试系统的校准提供理论依据。     

基于塞贝克效应的半导体气敏传感器的研制

利用塞贝克效应研制成功ZnO半导体气敏传感器。这种新型传感器能够输出0-100mV的直流电压,对于信号的放大与处理将十分方便。在实验中对20×10-6NO2气体进行检测,结果表明:传感器的输出电压(温差电动势),随着待测气体浓度而变化。因此,利用温差电效应制作气敏传感器是一条完全可行的新思路。     

原子层热电堆热(光)电探测器的原理及研究现状

概述了基于晶体的各向异性Seebeck效应的原子层热电堆热(光)电探测器的基本原理和优点,并从材料体系的选择和器件的主要应用等方面阐述了该类型探测器的国内外研究现状,预测了原子层热电堆探测器在新材料、材料维度和新热源探索等的发展方向。     

侧壁压阻式力传感器的研制与标定

在对现有微操作中夹持力问题进行分析的基础上,提出了一种基于面内侧壁压阻的力传感器加工方法,成功地在MEMS微夹持器上集成了压阻式的力检测传感器,对夹持力的检测反馈实现了微操作的闭环控制.该方法利用离子注入工艺和深度反应离子刻蚀（DRIE）工艺相结合制作检测梁侧壁压阻,改善了侧壁压阻工艺与其他工艺间的兼容性问题.最后通过压电叠堆驱动平台结合精密电子秤对压阻传感器进行了标定.测试表明,这种微力传感器加工技术可以很好地与其他工艺相兼容,力传感器的灵敏度优于72V/N,分辨率优于3μN.     

纤毛式MEMS矢量水声传感器的仿生组装

提出了一种纤毛式微机电系统（MEMS）矢量水声传感器的仿生组装技术.期望结合MEMS工艺和仿生组装工艺技术,解决复杂结构的仿生制造问题.文中简单介绍了仿生学理论以及定向探测机理.采用MEMS基硅微机械加工技术完成了传感器微结构的加工.通过模仿鱼类侧线器官神经丘感觉器的仿生结构,完成了传感器仿生微结构的组装,制作出纤毛式硅微仿生矢量水声传感器的模型样机.最后,完成了传感器的校准测试.测试结果表明,该水声传感器不但体积小、质量轻、结构简单,而且具有“8”字型的指向特性.该水声传感器的声压灵敏度为-197.7 dB（0 dB=1 V/μPa）.     

不同衬底条件对MEMS压阻传感器性能的影响

为了研究不同衬底条件对MEMS压阻传感器性能的影响,采用3种掺杂条件的衬底进行实验测试．在各步骤热过程后,对3种衬底条件下压阻区、引出区和保护框的方块电阻进行了测量和分析．通过对各部分方块电阻的测量可以看出,对于压阻区（P^-区）,A#和B#的方块电阻在开始注入扩散时相差很小,而由于注入杂质在高温下进一步扩散,衬底掺杂浓度对扩散后杂质分布的影响加大,方块电阻在后续的热过程中差别增大．通过比较不同衬底条件下各个热过程后的压阻数据,发现在3种掺杂条件中,20～40Ω·cm的衬底最符合预期压阻的设计．此结论已用于指导实际产品生产．     

基于MEMS技术的SU-8胶被动微阀片的设计与研制

为解决微流体在微流控芯片上的单向流动,进而实现生化反应的片上系统,采用微机电系统（MEMS）技术加工出SU-8胶微型阀片．SU-8胶阀片具有弹性模量和弹性常数低、开启压力小、反向泄漏小、易于加工等特点．从理论上分析了不同厚度（10μm,15μm,20μm,25μm）的微型阀片在不同压力作用下的挠度和应力分布,在相同尺寸和压力下,SU-8微阀片的挠度与传统的硅阀片的挠度相比要大10倍左右．讨论了有阻尼作用下的谐振频率以及过流特性。可知阀臂和阀座的尺寸是影响阀片性能的主要因素．给出了加工工艺,测试了阀片的正反向过流性能,以水作为工作物质,得到3种厚度阀片的过流曲线,其最大正向流速达到7000μL／min．     

Thermal Conductivity of Opacified Powder Filler Materials for Vacuum Insulations1

The thermal conductivity of powder fillings for load-bearing vacuum insulations is investigated. Different opacifiers have been tested in mixtures with perlite powder, precipitated silica, and fumed silica. Using temperature-dependent thermal conductivity measurements, the radiative thermal conductivity and the solid conductivity of the powder samples are separated. Additionally, the influence of the pressure load on the solid conductivity is studied. The thermal conductivities of silica powders with added opacifier powders (carbon black, magnetite, silicon carbide, titanium dioxide) can be as low as 0.003 W·m^–1·K^–1 if the powder boards are pressed with moderate loads. The use of microporous silica powders as filler materials allows internal gas pressures even beyond 10 hPa with only a moderate increase of the overall conductivity.     

A New Pulse Hot Strip Sensor for Measuring Thermal Conductivity and Thermal Diffusivity of Solids

The pulse hot strip method is a newly developed dynamic method to measure the thermal conductivity and thermal diffusivity of solids. It is based on monitoring the temperature response of a sample to a very short heat pulse liberated by a strip heat source. The instrument's uncertainty is estimated to be less than 3% for both quantities.     

New Transient Hot-Bridge Sensor to Measure Thermal Conductivity, Thermal Diffusivity, and Volumetric Specific Heat

A high sensitivity thermoelectric sensor to measure all relevant thermal transport properties has been developed. This so-called transient hot bridge (THB) decidedly improves the state of the art for transient measurements of the thermal conductivity, thermal diffusivity, and volumetric specific heat. The new sensor is realized as a printed circuit foil of nickel between two polyimide sheets. Its layout consists of four identical strips arranged in parallel and connected for an equal-ratio Wheatstone bridge. At uniform temperature, the bridge is inherently balanced, i.e., no nulling is required prior to a run. An electric current makes the unequally spaced strips establish an inhomogeneous temperature profile that turns the bridge into an unbalanced condition. From then on, the THB produces an offset-free output signal of high sensitivity as a measure of the properties mentioned of the surrounding specimen. The signal is virtually free of thermal emf’s because no external bridge resistors are needed. Each single strip is meander-shaped to give it a higher resistivity and, additionally, segmented into a long and short part to compensate for the end effect. The THB closely meets the specific requirements of industry and research institutes for an easy to handle and accurate low cost sensor. As the key component of an instrument, it allows rapid thermal-conductivity measurements on solid and fluid specimens from 0.02 to 100 W· m⁻¹·K⁻¹ at temperatures up to 250°C. Measurements on some reference materials and thermal insulations are presented. These verify the preliminary estimated uncertainty of 2% in thermal conductivity.     

隔气结构膜对真空绝热板热工性能及使用寿命的影响

真空绝热板具有良好的绝热性能,为节能目的,尤其是建筑领域,提供行之有效的热屏障,但其使用寿命成为诸多研究人员、制造商和用户最为关心的关键问题。隔气结构是维持真空绝热板内真空度的重要组成元件,其性能对真空绝热板的热工性能和使用寿命影响甚大。采用试验的方法只能在有限的时间内对其使用寿命研究,理论预测其使用寿命尤为重要。文章研究了气体和水蒸汽通过隔气结构膜渗透到板内对其等效导热系数的影响,采用数值分析的方法建立了相应数学模型,选取了三种典型隔气结构膜,测试了其相关性能参数指标,对其制得的真空绝热板,理论分析了导热系数变化规律,并对其使用寿命进行了评估。     

A Four-Terminal Water-Quality-Monitoring Conductivity Sensor

In this paper, a new four-electrode sensor for water conductivity measurements is presented. In addition to the sensor itself, all signal conditioning is implemented together with signal processing of the sensor outputs to determine the water conductivity. The sensor is designed for conductivity measurements in the range from 50 mS/m up to 5 S/m through the correct placement of the four electrodes inside the tube where the water flows. The implemented prototype is capable of supplying the sensor with the necessary current at the measurement frequency, acquiring the sine signals across the voltage electrodes of the sensor and across a sampling impedance to determine the current. A temperature sensor is also included in the system to measure the water temperature and, thus, compensate the water-conductivity temperature dependence. The main advantages of the proposed conductivity sensor include a wide measurement range, an intrinsic capability to minimize errors caused by fouling and polarization effects, and an automatic compensation of conductivity measurements caused by temperature variations.     

Measurements of the Thermal Conductivity of Molten Lead Using a New Transient Hot-Wire Sensor

The paper reports new measurements of the thermal conductivity of molten lead at temperatures from 600 to 750 K. The measurements have been carried out with an updated version of a modified transient hot-wire (THW) method, where the hot-wire sensor is embedded within an insulating substrate with a planar geometry. However, unlike previous sensors of the same type, the updated sensor works with the hot-wire divided into three thermally isolated parts. The operation of this sensor has been modeled theoretically using a finite-element (FE) analysis and has subsequently been confirmed by direct observation. The new sensor is demonstrated to have a higher sensitivity and a better signal-to-noise ratio than earlier sensors. Molten lead is used as the test fluid. It has the lowest thermal conductivity of any material we have yet studied. This allows us to probe the limits of our sensor system for the thermal conductivity of high-temperature melts. It is estimated that the uncertainty of the measurements is 3% over the temperature range studied. The results are used to examine the application of the Wiedemann–Franz (W-F) relationship.     

Thermal Conductivity of Methane-Hydrate

The thermal conductivity of the methane hydrate CH₄ (5.75H₂O) was measured in the interval 2–140 K using the steady-state technique. The thermal conductivity corresponding to a homogeneous substance was calculated from the measured effective thermal conductivity obtained in the experiment. The temperature dependence of the thermal conductivity is typical for the thermal conductivity of amorphous solids. It is shown that after separation of the hydrate into ice and methane, at 240 K, the thermal conductivity of the ice exhibits a dependence typical of heavily deformed fine-grain polycrystal. The reason for the glass-like behavior in the thermal conductivity of clathrate compounds has been discussed. The experimental results can be interpreted within the phenomenological soft-potential model with two fitting parameters.PACS numbers: 66.70 +f, 63.20 −e, 63.20 Pw, 63.50 +x.     

热激励硅谐振式微结构压力传感器若干关键参数设计

针对一种以方形硅膜片为一次敏感元件、硅梁为二次谐振敏感元件的热激励硅微结构压力传感器的实际结构,分析了其工作机理和产生热特性的机制.给出了考虑热特性情况时的传感器的被测压力与输出频率的特性方程;给出了传感器稳定可靠工作的条件;给出了梁谐振子的几何结构参数和激励、拾振电阻几何参数选择与位置设置的原则.     

高岭土在真空下的热分解行为

以含高岭石、一水硬铝石、黄铁矿的高岭土为原料,经过压块烘干后,在真空(15~50 Pa)、不同加热温度下,采用同步热分析仪(DSC-TGA)、X射线衍射(XRD)等分析手段对高岭土在真空下的热分解进行研究。DSC-TGA的结果与高岭石、一水硬铝石、黄铁矿三种矿物常压下的热力学计算出的分解温度相符。实验产物的XRD结果表明:在真空条件(15~50 Pa)下,一水硬铝石AlO(OH)在100~200℃之间脱水,300℃时脱水完全;黄铁矿FeS2在500~600℃分解,分解产物为FeS和S2,在700℃时,黄铁矿FeS2分解完全;高岭石Al2Si2O5(OH)4在实验煅烧过程中,在200~300℃之间脱水,生成非晶态的偏高岭石,比该矿在常压的脱水温度提前200℃左右。继而转变成A-lSi尖晶石,最后形成莫来石与方石英。实验结果与热力学计算符合,充分说明真空条件对高岭土中各种矿物分解产生气体的反应有较大的促进作用。在本实验三种矿物分解产生气体的过程中,先进行的反应对后一反应的发生影响不明显。     

Thermal Conductivity of Coated Paper

In this article, a method for measuring the thermal conductivity of paper using a hot disk system is introduced. To the best of our knowledge, few publications are found discussing the thermal conductivity of a coated paper, although it is important to various forms of today’s digital printing where heat is used for imaging, as well as for toner fusing. This motivated an investigation of the thermal conductivity of paper coating. This study demonstrates that the thermal conductivity is affected by the coating mass and the changes in the thermal conductivity affect toner gloss and density. As the coating mass increases, the thermal conductivity increases. Both the toner gloss and density decrease as the thermal conductivity increases. The toner gloss appears to be more sensitive to the changes in the thermal conductivity.